1999 - Volume 2 - Journal of Engineered Fibers and Fabrics

International Nonwovens Journal Home Page 

A SCIENCE AND TECHNOLOGY PUBLICATION 

Volume 8 No. 2 Fall, 1999 

Air Filters For Ventilating 

Systems — Laboratory and 

In Situ Testing 

Table of Contents 

Cover Story 

TABLE OF CONTENTS 

INJ DEPARTMENTS 

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Guest Editorial 

Director's Corner 

Emerging Technology 

Rsearcher's Toolbox 

Standards Development Forum 

Patent Review 

PAPERS 

Association Focus; TAPPI 

The Nonwoven Web 

Pira Worldwide Abstracts 

Association News 

Nonwovens Calendar 

Air Filters For Ventilating Systems - Laboratory and In Situ Testing 

Original Paper by Jan Gustavsson, Camfi 

Evaluation of the Filtration Performance of Biocide Loaded Filter Media 

Original Paper by Wayne T. Davis, B. Alan Phillips, Maureen Dever, Thomas Montie and Kimberly 

Kelly-Wintenberg, The University of Tennessee; and Sarah Macnaughton, Microbial Insights, Inc 

Characterization of Melt Blown Web Properties Using Air Flow Technique 

Original Paper by Peter Ping-yi Tsai, TANDEC, The University of Tennessee 

Foamed Latex Bonding of Spunlace Fabrics To Improve Physical Properties 

Original Paper by A. Shahani, Bell Atlantic; D.A. Shiffler and S.K. Batra, Nonwovens Cooperative 

Research Center, North Carolina State University 

Fiberglass Surface And Its Electrokinetic Properties 

Original Paper by Daojie Dong, Owens Corning 

Applications Of On-Line Monitoring of Dynamic Forces Experienced By Needles During Formation 

Of Needled Fabrics 

Original Paper by Abdelfattah M. Seyam, Nonwovens Cooperative Research Center, North Carolina 

State University 

Development of Thermal Insulation For Textile Wet Processing Machinery Using Needlepunched 

Nonwoven Fabrics 

Original Paper by Randeep S. Grewal, Flynt Fabrics; and Dr. Pamela Banks-Lee, North Carolina 

State University 

Comparison Of Trends In Latex Emulsions For Nonwovens and Textiles: 

China and the United States 

Original Paper by Pamela Wiaczek, Kline & Company 

Fiber Renaissance For The Next Millennium 

Author's Perspective by Arun Pal Aneja, DuPont 

Publisher Ted Wirtz President 

INDA, 

Association of the Nonwoven Fabrics Industry 



Sponsors Wayne Gross Executive Director/COO 

TAPPI, Technical Association of the Pulp and Paper Industry 

Teruo Yoshimura 

Secretary General 

ANIC, Asia Nonwoven Fabrics Industry Conference 

Editors Rob Johnson 609-256-1040 

rjnonwoven@aol.com 

D.K. Smith 602-924-0813 

nonwoven@aol.com 

Association Editor Chuck Allen INDA 

D.K. Parikh TAPPI 

Teruo Yoshimura ANIC 

Production Editor Michael Jacobsen Jacor Publications, Inc. 

201-612-6601 

mjacobsen@inda.org 

Cover Photo provided by AQF Technologies, Charlotte N.C. 

The International Nonwovens Journal is published by INDA, Association of the Nonwoven Fabrics Industry, P.O. Box 

1288, Cary, NC 27512; www.inda.org. Copyright 1999 INDA, Association of the Nonwoven Fabrics Industry. No part of 

this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including 

photocopying and recording, or by any information storage or retrieval system, except as may be expressly permitted in 

writing by the copyright owner. The magazine is sent free-of-charge to all members of INDA and TAPPI, P.O. Box 

105113, Atlanta, GA 30348; 404-209-727; Fax 404-446-6947; and ANNA (Asia Nonwoven Fabrics Industry Conference), 

Soto kanda 6-Chome Bldg. 3Fl, 2-9, Chiyoda-ku, Tokyo, 101, Japan. The International Nonwovens Journal can not be 

reprinted without permission from INDA. INDA¨ is a registered trademark of INDA, Association of the Nonwoven 

Fabrics Industry 


Editor's Corner 

To the Future 

GUEST EDITORIAL 

By Behnam Pourdeyhimi 

Ph.D., CText ATI, FTI; Professor, and Co-Director, Nonwovens Cooperative Research Center, North 

Carolina State University, College of Textiles 

I had the opportunity to attend both INDEX '99 and ITMA '99 earlier this year. At both, I listened to 

messages about continued growth of the nonwovens industry, and future prospects for the industry in the 

global economy. At these meetings, I met with companies involved in various segments of the industry, 

including raw material suppliers, roll goods producers, converters and fabricators of the end use 

products, and machinery manufacturers. 

What was perhaps the most interesting aspect of my visits was the fact that most of the processes and 

products on display did not exist two or three decades ago; those that did are now referred to as "aging" 

technologies. This is not surprising given the new developments exhibited at INDEX and ITMA, 

although even the "aging" processes have also been improved significantly over the same time period. I 

came back from these meeting with the feeling that nonwovens will continue to play a significant role in 

the polymer-fiber-textile enterprise for many years to come. 

In the near future ANNA/ANIC will be providing members to 

the Editorial Advisory Board from their geographic region. 

It has been estimated that this industry contributes more than 

$30 billion to the U.S. economy, and will continue to grow at a 

rate of at least 5-6% annually. This is indeed great news for the 

industry! 

As a professor and educator, however, I have to wonder about 

the availability of the trained human capital required to help 

sustain this industry. Presently, the nonwovens industry 

primarily undertakes in-house training of individuals with 

degrees in engineering or science. This has undoubtedly 

contributed to the innovations in the field; however, I am not 

certain if this can continue to be a viable option given the 

EDITORIAL ADVISORY BOARD 

Chuck Allen 

INDA 

Roy Broughton Auburn University 

Robin Dent Albany International 

Ed Engle 

Fibervisions 

Tushar Ghosh North Carolina State 

Bhuvenesh 

Goswami 

Clemson University 

Dale Grove 

Frank Harris 

Albert Hoyle 

Owens Corning 

Fiberglass 

HDK Industries 

Hoyle Associates 

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Editor's Corner 

complexities of the materials, processes and products available 

today. 

Gaining, and indeed maintaining, leadership in this emerging 

field requires substantial investment in human capital as well 

as inventing fundamentally new mechanisms for achieving 

"versatile" processing; i.e., processing of large volume and 

specialized materials with a substantially common production 

domain AND environmental compatibility. 

In order to maintain the present level of innovation, it is 

necessary to develop a more structured model for training our 

future nonwoven specialists. In academic institutions, our 

efforts in this regard should be focused on training these "new" 

personnel with sufficient breadth and depth in the variety of 

disciplines that impact the nonwovens industry. This 

multidisciplinary education will well prepare them for a role 

with the new, versatile and sustainable technologies that will 

require a fundamental, adaptable knowledge of process 

synthesis, integration and subsequent transfer to industrial 

production. It is clear that industry and academia need to 

engage in open debate on the important matter of to how to 

prepare for the future. 

Ed. Note: Dr. Pourdeyhimi has recently joined the faculty at 

NCSU as Co-Director of the NCRC. Dr. Pourdeyhimi was 

most recently on the faculty at Georgia Tech and authored an 

article in the SPRING, 1999 issue of INJ. 

Marshall 

Hutten 

Hyun Lim 

Hollingsworth & 

Vose 

E.I. duPont de 

Nemours 

Nelson Industries 

Joginder Malik 

Alan 

Meierhoefer 

Dexter Nonwovens 

Michele 

Mlynar 

Rohm and Haas 

Graham Moore 

PIRA 

D.V. Parikh U.S.D.A.-S.R.R.C. 

Behnam 

Pourdeyhimi 

Georgia Tech 

Art Sampson Polymer Group Inc. 

Robert 

Shambaugh 

Univ. of Oklahoma 

Ed Thomas BBA Nonwovens 

Albin Turbak 

Retired 

Larry 

Wadsworth 

Univ. of Tennessee 

In the near future ANNA/ANIC will be 

providing members to the Editorial 

Advisory Board from their geographic 

region. 

— INJ 

Return to International Nonwovens Journal 

Home Page & Table of Contents 

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Directors Corner 

THE DIRECTOR’S 

CORNER 


A few years ago there was considerable concern about the possibility of electromagnetic radiation fields 

causing human cancers. The primary concern focused on high power transmission cables that frequently 

traverse residential areas. Many people were concerned that living under or around high powered 

transmission lines was injurious to health, particularly the health of children. 

As a result, there was considerable government-sponsored research to determine the reality of this 

concern and to quantify the risks involved. One particular study provided considerable fuel for this 

controversy and resulted in numerous expensive actions taken as a precautionary measure. 

The study was produced by a scientist named Richard Liburdy; in it, he stated that he had proved a link 

between high voltage lines and cellular changes in the body that could lead to cancer. This resulted in an 

acceleration of research devoted to the topic, despite the fact that many other studies, particularly those 

emanating from Europe indicating that no relationship existed. 

Shortly after the 

study received wide 

circulation, a 

whistleblower told 

the Federal 

Government, which 

had funded this 

particular research, 

that Liburdy had 

manipulated his data. 

The Office of 

Research Integrity, a 

NON-COMPLIANCE CORRELATION 

EPA Act 

Non-Compliance Events 

CAA — Clean Air Act 0% 

CERCLA — Comprehensive Environmental Response, 

9% 

Compensation and Liability Act (Superfund) 

CWA — Clean Water Act 29% 

EPCRA — Emergency Planning and 

Community Right-to-Know Act 

7% 

RCRA — Resource Conservation & Recovery Act 23% 

TSCA — Toxic Substances Control Act 12% 

bureau within the U.S. Department of Health and Human Services that monitors many federally funded 

research projects investigated. Further examination revealed that Liburdy had discarded data in preparing 

a graph for his publication which did not fall on the line purporting to support the hypothesis. In fact, 

further examination revealed that Liburdy had used only 7% of the data generated during his studies. As 

a result, Liburdy requested of the scientific journals that had published his work that three key 

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paragraphs be rescinded. Despite this action Liburdy claimed that he had done nothing wrong. However, 

he did leave the Department of Energy’s Lawrence Berkeley National Laboratory, where he was 

employed, and he has lost a portion of the $3.3 million grant from The National Institutes of Health, 

Department of Energy and Department of Defense. 

During and since these investigations, other studies have been published, all of which confirm the fact 

that there is no link between the electromagnetic radiation field and living organisms. Unfortunately, Mr. 

Liburdy’s deception kept the unfortunate myth alive for a period of time and fostered many actions of 

"prudent avoidance;" the latter term has been concocted to mean that if there is even a hint of health 

problem, play it safe and avoid exposure. As a recent article in the Wall Street Journal points out (Wall 

Street Journal, July 27, 1999) prudent avoidance "constitutes a rejection of science and a triumph of fear 

over reason" and, as physicist David Hafemeister of California Polytechnics State University notes, 

"prudent avoidance is a delight for plaintiff lawyers since it is essentially a conclusion that the danger is 

probable." 

In this case prudent avoidance resulted in massive expenditures in many different areas and conditions. 

Unfortunately, researchers seeking additional government funds know that research results which 

promote the concept that a growing problem exists can help assure a continuation of grants. This has 

resulted in what some critics have called "regulatory science." Unfortunately, the Liburdy episode has 

not done much to discourage this viewpoint. Although the falsification of data by Mr. Liburdy was 

exposed in 1995 he remained on the job until this past May. His "punishment" for his unscientific 

behavior consisted of an agreement that he would not apply for more Federal grants for a period of three 

years. 

Science in the Courtroom 

In recent years there has been considerable concern about the impact of science in litigation and in the 

courtroom environment. Unfortunately, many examples exist where testimony offered in court cases 

have been labeled as "science," but has failed to meet the standards normally expected of a scientific 

discipline. In some cases, the deviation from scientific principles has been appalling. 

As Supreme Court Justice Stephen Breyer wrote in an opinion last year: "Society is becoming more 

dependent for its well being on scientifically complex technology, so, to an increasing degree, this 

technology underlies legal issues of importance to all of us." Because of this increasing importance of 

science in the courtroom, attention has been focused on ways to insure that only the highest standards are 

employed in such contributions. 

The Supreme Court of the U.S. has made it very clear that the judges themselves are responsible for the 

accuracy and reliability of scientific evidence presented in their courtrooms. There have been several 

recent cases adjudicated by The Supreme Court that has stressed the absolute necessity to keep junk 

science out of technical testimony. 

While there can be widespread agreement on the objective, the means to accomplishing this goal can be 

difficult delineate. 

Some judges have enlisted the use of independent experts. The judge in the silicone breast implant case, 

for example, appointed a four-member panel of independent experts to help him sort through the science. 

An encouraging approach to develop a system that insures the highest scientific standards in the 



courtroom has been made by the American Association for the Advancement of Science (AAAS). This 

organization has been working with a group from the American Bar Association to study the problem of 

scientific evidence in the courtroom. Representatives from these two groups have been meeting for the 

past few years as the National Conference of Lawyers and Scientists. In the past few months, the AAAS 

has started a five-year demonstration project in which independent scientists with the appropriate 

expertise can be identified for judges to consider as scientific resources in determining the truth in 

litigation. 

Although the mechanism has not been completed, the project is making progress, including establishing 

and experimenting with the process by which experts are selected. Several subsidiary bodies chosen by 

AAAS staff and the advisory committee will attempt to develop procedures for both identifying and 

recruiting such experts. 

Another committee within the national conference is attempting to develop guidelines to screen experts 

for potential conflicts of interest. The use of anonymity in describing potential experts will likely be 

helpful in the selection process. 

Other groups within the conference are working on the methods to make expert lists available and to alert 

the judges of the appropriate procedures in utilizing such services. Another activity is directed toward 

educating the scientists as to the intricacies of the legal process. 

While the initial efforts are being focused on Federal courts, it likely the project can be extended to State 

courts if the procedure proves successful. This is most desirable, as the State courts are the venue of most 

tort litigation and especially the most outrageous tort litigation. 

Hopefully these efforts can prove successful and the "legal lottery" can be eliminated along with the 

presence of junk science in the courtroom. 

The Value of People 

It has often been said that a company’s most valuable single asset is the people they have. The same can 

be said of the academic environment; quality of the researchers controls the quality of the research. 

Finding, hiring and keeping good people is a never-ending task for the research administrator, whether in 

industry, academe, or elsewhere. 

One of the tools in identifying the best candidates for the job is embodied in a variety of pre-employment 

assessments. These are generally tests that usually consist of questions relating to the skills, behaviors 

and attitudes that are necessary for a particular job and a particular environment. These tests can take 

many different forms. The idea behind the test is to identify those applicants with the best chance of 

becoming productive scientists and contributors to the industrial or academic research effort. 

The desirability of picking the right employee is also coupled with the importance of retaining the 

employee. The average length of employment of an individual at any professional job in the United 

States has been declining in recent years and is estimated to be somewhere between two and four years 

by some human resources specialists. 

Along with the need to retain good researchers is the growing recognition that everyone needs balance in 

their lives. There must be meaning and satisfactions in their work, but this needs to be balanced with 

their personal, family and private aspirations. A recent review of this situation by one human resources 



specialist, Roger E. Herman, gives five reasons why people leave employment and what to do about the 

situations. His list of five reasons for departure include the following: 

● "It doesn't feel right around here." 

● "They wouldn't miss me if I were gone." 

● "I don’t get the support I need to get the job done." 

● "There’s a new opportunity for growth somewhere else." 

● "I’m not being adequately compensated." 

Herman stresses the essential point that each individual needs to feel valued in his/her situation. It is 

important to clearly exhibit to the employee how their effort fits in with the overall activity and how it 

contributes to the success of an organization. It has been found that compensation is not the motivator it 

once was. However, it is still important to have a competitive benefits package. 

Of equal importance are the subtle "perks" that say "I am valued." There is a need for public recognition, 

and the research director that is innovative in selecting the method of such recognition is making a wise 

investment. 

Incidentally, a book entitled "1001 Ways To Reward Employees" (Workman Publishing Co. Inc; New 

York, NY) has been selling very well. Its author, Bob Nelson (Nelson Motivation, Inc.; P.O. Box 

500872, San Diego, CA 92150; 619-673-0690; Fax: 619-673-9031; www.nelson-motivation.com) has 

written several books on management and business skills, and is a very popular speaker. 

Protecting The Environment and Your Staff 

Environmental protection, along with employee safety and health, are research director's concerns that 

seldom actually benefit the bottom line. These responsibilities are viewed by many in the same way that 

a lot of plant managers view filtration: "Filtering our product doesn’t add any value, it simply adds cost." 

However, this attitude relates to an old adage that says: "Do it right the first time and you won’t have to 

do it the second time." 

It is true that the industrial or academic or research director spends more time, effort and research 

resources on these two factors than the research director of a couple generations ago. Every old timer can 

relate stories of how a critical plant run was made late at night with a "jury rig setup, taking more than a 

few risks." However, those times are gone and will never return. Today’s reality is that the research 

administrator has responsibility for occupational health and safety of the group, along with an 

environmentally sound operation. 

In terms of industrial plant sites, considerable pressure has been applied by the Environmental Defense 

Fund (EDF) and the Federal Government’s EPA (Environmental Protection Agency). A few months ago, 

these two organizations jointly launched an internet web site designed to pinpoint environmental 

problems. No plant manager, or research director for that matter, would like their operation's mistakes, 

hazards, accidents and just unfortunate incidents broadcast to the entire world. However, this web site 

lists plant and location emission problems by their Zip Code, making it relatively easy for anyone to 

check into the performance of their neighbor. It is a little bit like having the contents of your closet 

exposed, skeletons and all. 

While many industrial concerns initially expressed dismay at the thought of such exposure, the result has 

been surprisingly different. This site has not been a pandora's box of problems and a source of major 



embarrassment. In most cases, the neighbors, the city officials and others have been aware of the 

situation and also aware of the company or laboratory efforts to address the problem. 

Rather interestingly, some trade associations for the chemical, petroleum and other manufacturing 

industries have adopted the information site technique to inform and educate their neighbors as to their 

problems and their remedial efforts. 

As an example, the Chemical Manufacturers Association (CMA) is launching a web site called 

"Chemical Guide." This will be an information site to the plant, the community, the employees and the 

surrounding neighbors. The CMA has developed templates that member companies can use to report 

information ranging from environment, health, and safety statistics to financial information, and even job 

postings. As a CMA spokesman has indicated, "It’s not an attempt to change the public’s perception of 

the industry; it’s meant to personalize our facilities." 

In a similar vane, many organizations have "gone public" with respect to injury and illness reports. An 

example is a new web site that provides online versions of environmental, health and safety reports; it is 

being offered by 111 companies in the U.S. (www.ehsreports.com). This type of internet site was rather 

strongly tilted to environmental reports when initiated; now, many companies are trying to strike a better 

balance in providing health and safety information. 

Laboratory tours, plant visits and similar activities where appropriate, can go a long ways to building 

positive relationships with neighbors, employee families and other interested parties. Such activities can 

also help to boost the esteem of employees and staff members. In a time of electronic information, it is 

often more prudent to exploit than to resist. 

Employee Safety Initiatives 

In line with the research director’s concern with employee safety, a frequently asked question is: "What 

legal rights do employees have to take actions to see that their employer complies with OSHA 

Standards?" 

This is an interesting and rather important question for research directors, plant managers and 

administrators in general. A rather definitive answer to this question was recently provided by Daryl 

Brown of J.J. Keller & Associates (dbrown2@jjkeller.com). Mr. Brown indicated that The Occupational 

Safety and Health Act of 1970 created by OSHA within the Department of Labor was inaugurated to 

encouraged employers and employees to reduce workplace hazards and to implement safety and health 

programs. This law gives employees many rights and responsibilities, including the rights to do the 

following: 

• Review copies of appropriate standards, rules, regulations and requirements that the employer should 

have available at the workplace. 

• Request information from the employer on safety and health hazards in the workplace, precautions that 

have been taken and procedures that should be followed if the employee is involved in an accident or is 

exposed to toxic or hazardous materials. 

• Have access to the employee’s exposure to harmful materials, and medical records that are relevant to 

the situation. 

• Request the OSHA area director to conduct an inspection if they believe that hazardous conditions or 



violations of OSHA Standards exist within the workplace. 

• Have an authorized employee representative accompany the OSHA compliance officer during any 

inspection tour. 

• The right to respond to questions from the OSHA compliance office, particularly if there is no 

authorized employee representative accompanying the compliance officer doing the inspection tour. 

• The right to observe any monitoring or measuring of hazardous materials and to examine the resulting 

records. 

• Have an authorized representative or the employee themselves review the OSHA 200 Log at a 

reasonable time and in a reasonable manner. 

• Object to the abatement period set by OSHA for correcting any violation in a citation issued to the 

employer; this is done by writing to the OSHA area director within 15 working days from the date the 

employer receives the citation. 

• The right to be notified by the employer if the employer applies for a variance from a OSHA standard; 

also, the right to testify at the variance hearing and to appeal the final decision. 

• The employee has the right to have their name withheld from their employer upon their request to 

OSHA, if a written and signed complaint is filed. 

• The right to file a discrimination complaint if the employee is punished for exercising any of the above 

rights or for refusing to work when faced with an imminent danger of death or serious injury and there is 

insufficient time for OSHA to inspect the situation. 

While this listing of the employee rights is rather lengthy, a consideration of each item rather clearly 

establishes the appropriateness of each of these rights. 

Violations of Environmental Laws 

Anyone who has been involved in a laboratory or plant inspection by EPA (Environmental Protection 

Agency) inspectors knows how stressful this situation can be. In many cases, honest efforts have been 

made to do an effective job and to abide by EPA Regulations. The sheer volume and complexity of such 

regulations, however, often leaves the whole operation on a rather "chancy" basis. 

In a rather unusual exercise, the EPA and the Chemical Manufacturers Association (CMA) recently 

collaborated on an effort to determine why companies fail to comply with environmental regulations. 

The CMA was very willing to participate, as explained by their legal counsel, because "historically the 

EPA had been addressing only the symptoms of violations, and here was the opportunity to find out what 

the causes are." 

The three-year project was carried out as "Root Cause Analysis Pilot Project." EPA prepared the survey 

and sent it to 50 member companies who had encountered problems with violations between 1990 and 

1995. These violations were non-criminal, but represented a breach of the regulations, nevertheless. 

The report on the results of the survey (http://www.epa.gov/oeca/ccsmd/rootcause.html) detail six 

primary root causes for facility violations. These causes were as follows: 

1. Facility unaware of the applicability of specific regulation. 



2. Human error in judgment or responsibility. 

3. Failure to follow EPA procedures. 

4. Faulty equipment design or installation. 

5. Problems with compliance by contractors. 

6. Various communication difficulties. 

From this study, it was determined that certain kinds of compliance problems are most regularly 

associated with particular laws. Specifically, it was found that the laws relating to two federal acts have 

more than one- half the violations involved, primarily because the laws were confusing and ambiguous. 

These two items were EPCRA (Emergency Planning and Community Right-to-Know Act) and RCRA 

(Resource Conservation & Recovery Act). On the other hand, the problems with the Clean Air Act 

(CAA) did not involve misunderstandings or permit violations. The violations that did occur regarding 

the CAA all involved operational and procedure-related problems, such as equipment failure and similar. 

The report results are summarized in the chart at the top of this page. 

Again, under the Clean Water Act, most of the problems with faulty water discharges had their basis in 

the equipment installation or design. 

Also, it developed that companies which have environmental audit programs and corporate policies, 

goals and targets for regulatory compliance were the best performers as to compliance. These companies 

also reported that when violations were found, their emergency management systems were usually 

changed to avoid recurrence of the problems. 

From this study, a number of recommendations for both EPA and industry were provided. For EPA, it 

was suggested that the agency articulate its regulations more clearly and provide immediate compliance 

assistance and "plain-English" guides for every new rule. Also, it was suggested that EPA could work 

more closely with state and environmental agencies to insure that regulations are interpreted consistently. 

On the part of industry, it was suggested that more effort should be devoted to the development of 

comprehensive environmental management systems and the promotion of a increased level of awareness 

of such systems amongst all employees. Accurate, standardized operating procedures and improved 

employee training were also recommended. 



—INJ 



EMERGING 

TECHNOLOGY 

WATCH 


Sunlight Barrier Fabrics 

Because of publicity, there is a heightened awareness of the dangers of skin cancer due to exposure to the 

sun's rays. The risk is not insignificant, as more than a million cases of skin cancer are diagnosed in the 

United States each year, according to the American Academy of Dermatology. About 45,000 of these 

cases will be the deadly strain of skin cancer called melanoma, where the cancerous growth penetrates 

the skin layers into the underlying tissue. Melanoma kills over 7,000 people a year in the U.S. 

Responding to this hazard, there has been considerable interest in the use of clothing to protect against 

the deleterious effects of the sun's rays. Clothing, of course, does not eliminate the need for sun block 

creams and lotions on exposed areas of skin. However, for most of the body surface, adequate clothing 

can provide a very effective sun block. 

The problem is that in the summertime adequate clothing may be discarded in preference for very light, 

open fabrics that are more cool, comfortable and stylish. As a result, there has been considerable interest 

in recent years in developing fabrics specifically designed to block the sun and yet provide comfort and 

aesthetics that are normally associated with summertime clothing. 

If a fabric is heavy enough, it can effectively block the sun's rays. However, there has been considerable 

effort to develop fabric finishes for lightweight fabrics that can still provide adequate protection and yet 

be lightweight, open, breathable and stylish. 

This has resulted in a rather sudden growth in fabrics and clothing exhibiting good blockage of sunlight 

and thereby give strong protection against the problems associated with sunlight and human skin. 

Unfortunately, no standardized techniques have been developed in the United States for measuring how 

well a fabric blocks sunlight. Australia does have a standard method that applies to new, dry materials. 

There are efforts underway in the United States to establish a voluntary standard. 

In the meantime, companies that promote special fabrics as a solution to the problem are utilizing a 

variety of methods to measure the effectiveness. Clothing that is wet or that has been washed repeatedly 

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can have a very different ability for blocking the harmful effects of the sun. 

Some apparel companies have focused on this market niche and offer a variety of clothing claimed to 

provide considerable protection. Such apparel generally is quite expensive, however, and the consumer is 

left to gauge whether the additional expense is worth the claimed protection. 

At least one company in Israel has developed a finish technology which it claims provides the perfect 

solution to UV protection. As can be expected, the major focus of this effort has been on fashionable 

apparel fabrics, but there are indications that this technology will be extended to nonwoven structures as 

well. 

The process developed by Golden Guard Technologies Limited apparently involves the formation of a 

strong, flexible, breathable and translucent polyurethane finish that incorporates UV absorbers and 

attenuators. It is claimed that fabrics that transmit nearly 50% of the UV light before treatment, show a 

transmission of only 2-4% after treatment. The claims also indicate the finish results in a minimal impact 

on the moisture-vapor transmission rate and on the fabric hand and drape. This protection is unaffected 

by moisture, perspiration and machine washing, and is durable to abrasion, along with wear and tear, 

according to the developers (Golden Guard Technologies Ltd, 21 Havaad Haleumi Street, P.O. Box 

16120, Jerusalem 91160, Israel; 972-2-675-1123; Fax: 972-2-675-1195;. www.sunprecautions.com and 

www.sunprotection.com. 

Reactive Protective Clothing 

The category of "protective clothing" covers a broad range of hazards. As discussed in the item above, 

even sunlight can be a focus, and an appropriate one, for protective clothing. Anyone who has dealt with 

a baby diaper knows that it is also a form of protective clothing. 

More specialized hazards are being considered, however, and some innovative research is being devoted 

to such hazards. 

A recent development shows a rather dramatic approach to a specific situation, that of clothing worn by 

agricultural workers, specifically those workers exposed to a significant amount of pesticides. In many 

such cases the pesticide can pass through the clothing to the skin of the worker and there constituted a 

significant hazard. 

The solution worked out by researchers at the University of California-Davis involved clothing treated 

with chemicals to detoxify such pesticides. These investigators treated cotton fabric used to make shirts 

with a cyclic hydantoin compound, which grafted onto the cellulose backbone of the cotton fiber. The 

fabric is then treated with a bleaching process similar to that normally used in washing clothing. 

This process, using sodium hypochlorite solution, converts the hydantoin moiety into a halamine group. 

Interaction of the halamine group on the surface of the shirt fabric with carbamate-type insecticides 

results in the carbamate breaking down into small, harmless fragments. In the process, the halamine is 

converted back into the hydantoin. Washing the clothing, with a bleach treatment, then regenerates the 

halamine, ready to provide the protection. 

Thus, the garment is able to go through a cycle: (1) providing protection, (2) washing and bleaching, (3) 

regeneration of active site, ready to again provide the protection. 



Chlorine Bleach 

R - N - H 

...............> R - N - Cl 


Paperless Society ... The use of wireless communications, innovative displays and individualized web 

publications will help reduce the reliance on paper for many activities. Advanced display systems may 

imitate paper in flexibility and portability. The researchers suggest that one approach will involve 

projecting images directly on the retina of the eye. This capability, coupled with a cellular phone, could 

provide faxes and customized news anywhere. For paper products that continue to be used, 

biodegradable inks will be more common. 

Molecular Design ... The use of molecular design for catalysts can make chemical reactions and 

processes so precise that little or no wastes are produced. It suggests that sensors designed at the 

molecular level will monitor material and chemical manufacturing processes more precisely. This will 

help to halt or correct processes that are sensitive to temperature changes and other parameters. This 

breakthrough may expand uses of nonwovens, but may also have an impact on the production of 

nonwoven products. 

Bioprocessing ... This concept utilizes microorganisms and plants that will "grow" environmentally 

friendly chemicals and biological products. Included among these materials may be drugs, proteins and 

enzymes for many uses. Producing chemical feedstocks, fuels and pharmaceuticals in this manner will be 

cost effective and better for the environment. The researchers suggest that microorganisms retrieve from 

extremely hot, cold or forbidding environments (extremozymes, such as are recovered at hot holes in the 

ocean floor) may expand the range of temperatures and conditions used in manufacturing biotechnical 

products. This may create opportunities for new, environmentally friendly bioprocesses while saving 

time and energy. 

Real-time Environmental Sensors ... By the use of yet-to-be-developed sensors, supermarkets could 

detect the presence of bacteria and other dangerous pathogens in food. Workplace air quality could be 

monitored to prevent "sick building syndrome." Other benefits that may result from monitoring in the 

environment include control of airplane and other transportation environments, preventing infections in 

hospitals and in municipal water supplies and in guarding against pathogens potentially used in 

biological terrorism. 

Enviro-manufacturing and Recycling ... Greatly enhanced recyclability of a whole range of products 

may change the complexion of entire environmental protection in the future. Increased use of 

biodegradable material in such things as plastics, paper, cars and computers will have an impact. Dry 

cleaning with liquid carbon dioxide will minimize or eliminate this source of environmental pollution. 

Recycling will become "second nature" to all of the citizens of the world, and recyclates will be a major 

resource for future civilizations. 

Lightweight Cars ... As the weight of automobiles is reduced by the use of advanced materials, the 

family sedan will get at least 80 miles per gallon of gas, generate less pollution and use more recycled 

materials. Lighter weight cars will be built with less steel and more lightweight aluminum, magnesium, 

titanium and composites. Advanced metal forming techniques will provide precisely the strength needed 

at every point. The 150 pounds of glass used in today's cars will be cut by a third or more by the use of a 

composite sandwich of glass and plastic. Today's 100-pound air conditioners will weigh half as much, 

particularly as glass is specially coated to reflect or absorb heat radiation. 

While some of these concepts may sound far fetched, many of them already have a running start in 

parent technology. Further details on the environmental technology forecast coming from the U.S. 

Department of Energy can be obtained: Greg Koller at Pacific Northwest National Laboratory; 



greg.koller@p&l.gov; 509-372-4864; http://www.pml.bill/news/back/envirbg.htm. 

—INJ 




Researchers Toolbox 

RESEARCHERS 

TOOLBOX 


Good ideas are always welcomed by the effective researcher. Good ideas can help get a difficult job done 

easily. Sometimes the right method or tool can get results that would be difficult to do any other way. 

Occasionally, the right idea provides a result that simply could not be accomplished otherwise. Hence, a new 

trick to put into the collection of tricks is always a worthwhile addition. If you have such an item to share, 

please let us know so we can include it in a future offering. 

Here's hoping that one of the current collection will prove useful. 

Temperature Indicators 

In dealing with thermal processes it is sometimes vital to know the maximum temperature reached by a fabric 

or system. It would be very convenient to be able to insert something that would register the maximum 

temperature, or would give a signal if a certain temperature is achieved. 

A quick, inexpensive and easy solution to this need can often be obtained with the use of temperature monitor 

product. These can be paper or film label products having a window or small panel that changes color upon 

being exposed to a set temperature. Often a label or tape product will carry a series of four-to-eight spots that 

correspond to a specific temperature. When the product is exposed to that temperature, the spot changes from a 

light color to black or some such dark color, so there can be no doubt that the temperature was experienced. 

Self-adhesive temperature monitoring labels can be attached to a web undergoing thermal treatment, giving a 

positive indication that a certain temperature was achieved within the web. Such monitoring labels can have 

spots indicating a temperature of 100F between each rating. Other styles have temperature differentials of 250 

or 500 F between spots. The spots or indicator panels can have a variety of shapes and configurations, 

including circles, micro-dots, buttons, bars, and forms of bull's eye, clock and thermometer configurations. 

In general, the temperature range of 1000 to 5000 F is available, and an accuracy of 1% is guaranteed. Such 

temperature monitoring systems can also be provided in a pencil or stick version, which allows a mark to be 

made on a surface which then changes as that specific temperature is achieved. Also, the products are provided 

in paint form so that a cover or machine housing can be converted into a temperature-indicating probe. 

The monitoring tape product is often used with fusing ovens or fusing presses, to confirm the fact that a 

temperature adequate for a fabric bonding step has been achieved. This can be done by placing the indicator on 

a belt traversing the oven, or between layers of fabrics or sheets. This has been particularly useful in 

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applications involving the bonding of nonwoven fusible interlinings and interfacings to outer face fabrics. 

A well-established source for such products is Tempil, Inc. (2901 Hamilton Boulevard, South Plainfield, NJ 

07080; 800-757-8301; Fax: 908-757-9273). Their products can also be reviewed at http://www.tempil.com. 

Supercritical Fluids in 

Fibers Research 

Considerable interest has been shown in the use of supercritical fluids (SCF) in a wide variety of experimental 

and research applications. Where such detailed interests exist, applications almost invariably follow. 

The use of SCF methods in analytical laboratories has grown substantial over the past few years. This has been 

applied especially to extraction and chromatographic methods, where the elimination of toxic or difficult 

solvents has been a boon, along with the accompanying greatly reduced extraction times. 

A very interesting application of SCF technology in the fibers sector has recently come out of research work 

done at the Georgia Institute of Technology. This has focused on the dyeing of fibers, textiles and polymers 

and likely presages further search for suitable applications in the fibers and polymer sectors. 

One of the most popular solvents for using SCF technology is carbon dioxide. This solvent is especially 

attractive as it is nonflammable, nontoxic and low cost. It is easily separated from other solvents and 

substrates, and when so released, it is non-polluting. This solvent is particularly useful with polymeric 

materials, as it behaves as a plasticizer and can swell many polymers. Because of this attribute, its low 

viscosity and its high solute diffusivity, it can penetrate many polymers with ease. This character also allows 

the solvent to carry many materials into polymeric substrates, fostering mass transfer processes. 

SCF carbon dioxide is easily absorbed by many polymers. In some cases, the solvent can plasticize glassy 

polymers at relatively low temperatures; with rubbery polymers above their glass transition temperatures, the 

polymer volume can be substantially increased. These properties can aid in extraction of materials from the 

polymers, or conversely can aid in the transport of materials as additives or impregnants, depending upon 

specific conditions employed. 

Carbon dioxide is a gas at normal conditions of temperature and pressure. However, if the temperature is 

sufficiently lowered, the gas can be converted into a solid (dry ice). If the pressure is increased sufficiently, the 

gaseous carbon dioxide is converted into a solid or a liquid, dependent upon the temperature. At one condition 

of temperature and pressure, all three phases of the gas (solid, liquid and gas, the triple point) can exist in 

equilibrium; for carbon dioxide, the triple point is 310 C and 74 bar. pressure. Above this point, the material 

can generally be maintained in the liquid state, the preferred state for SCF work. By judicious selection of the 

pressure and temperature, diffusion rates can be controlled for extraction work or for impregnation processes. 

The work at Georgia Tech focused on the use of SCF carbon dioxide for the dyeing of fibers, textiles and 

polymers. Hence, the capability of the system for impregnation was particularly studied. These efforts 

confirmed the basic capabilities of the system, as reported by others. The research was extended by studying 

both phases of the dyeing process, the solubilization of the dyestuff molecule and the diffusion into the 

polymer matrix. 

Rather surprisingly, the Georgia Tech researchers found that the dyestuff could have low solubility in the 

solvent and still be effective in dyeing. They concluded this result was due to the fact that SCF dyeing can be 

effective because of the high partition coefficient, the dyestuff molecule preferring the polymer environment to 

that of the solvent. This property made for high dyeing efficiency and minimized dyestuff loses in the disposed 

liquor and vessel walls. 

As might be expected, the treatment did result in the extraction of some oligomers and surface agents from 



polyester fibers, for example. Other researchers have shown that such treatment can also affect fiber 

morphology, but no more so than the effects of heat and tension. 

Despite the fact that special equipment is required to obtain the temperatures and pressures needed, the 

interesting results of this work, and the inherent simplicity and cleanliness of the process, suggest utility of 

SCF technology in other fiber research and applications. 

For more information, see: Drews, M. J. and Jordan, C., Text. Chem. and Color. 30, 13-20 (1998). The work at 

Georgia Institute of Technology is summarized at: Kazarian, S. G., Noel, H.B., and Eckert, C.A., Chemtech, 

36-41 (July 1999). 

Microthermal Analysis 

Thermal methods of chemical and physical analysis are well-established techniques for characterizing and 

quantifying the morphology and composition of polymers and fibers. Differential scanning calorimetry (DSC), 

thermogravimetric analysis (TGA), thermomechanical analysis (TMA) and dynamic mechanical analysis 

(DMA) are all useful resources on the palette of the fiber and polymer scientist. 

By adding the option of temperature modulation superimposed on the conventional linear heating or cooling 

program, further information and resolution is possible in many of these cases. 

Even with such extensions of the basic techniques, however, these methods give only an averaged or a 

sample-averaged view of the condition within a polymer matrix. In order to measure the thermal properties of 

a small domain with the polymer, it is generally necessary to go to a microscopic scale. With some restrictions, 

secondary ion mass spectroscopy (SIMS) or X-ray photoelectron spectrometry (XPS) can provide some 

focused information, but these techniques have limitations and complexities. 

The efforts to bring together the capabilities of both thermal methods with microscopic techniques have 

resulted in the commercialization of an instrument called the Micro-Thermal Analyzer, specifically, the TA 

2900. The instrument combines the capabilities of thermal methods and micro visualization. It is achieved by 

combining an atomic force microscope (AFM) with a thermal probe. 

The TA 2900 is capable of providing four images or views of the surface of a sample: 

1. Topography 

2. Thermal conductivity 

3. Modulated temperature (amplitude) 

4. Modulated Temperature (phase) 

After these images have been acquired, any specific location on the sample can be further analyzed by what the 

instrument producer calls "Micro-Thermomechanical Analysis" and "Micro-Modulated Differential Thermal 

Analysis." The manufacturer claims these "micro" techniques are comparable with the usual "macro" 

counterparts. 

By means of this micro-thermal methodology, polymer blends can yield useful information. If the blends are 

immiscible, a two-phase domain structure results; the thermal properties of each individual domain can then be 

determined. If a single phase results, indicating miscibility, this becomes apparent from the thermal properties 

of this main phase. 

Similar chemical and physical information can be obtained with this equipment and technology on 

multi-layered films, indicating the thermal composition and compatibility of the various layers. The thermal 

nature, leading to precise characterization, of defect areas have also be explored by this technology. 



While the equipment is rather expensive, some consulting physical testing laboratories are acquiring the 

equipment and offering customized analyses. 

Source of the equipment: TA Instruments Ltd., Europe House, Bilton Center, Cleeve Road, Leatherhead, KT 

227UQ, Surrey, UK; 44+1372/360-363; Fax: 44+1372/360-135; tlever@taeurope.co.uk. 

Wetting of Nonwoven Fabrics 

The wetting of a nonwoven fabric by water and other liquids is of critical importance in many nonwoven 

applications. The most obvious situation, and one which has been studied extensively, is the wetting of 

nonwoven topsheet of a diaper by urine voided by the wearer. A rapid wetout and passage of the liquid through 

the nonwoven is critical to the performance of baby diapers and similar absorbent sanitary products. 

Standard test methods have been developed and carefully studied to measure the property of fabric wetting in 

this setting. Nonwoven diaper facing typically requires a wet-out or strike-through time of only a few seconds 

to be acceptable by most converters. 

The wetting performance of a fabric can be determined quite simply: Place a drop of water from an eyedropper 

or similar device to give a relatively constant size drop; carefully observe the drop and determine the time 

required for the drop to be absorbed into the fabric. Once wetting of the liquid occurs, absorbency into the 

fabric generally occurs very rapidly. If the droplet stays on the surface as an intact sphere for a considerable 

period of time, the fabric has poor or no wetting performance. 

Water (pure or otherwise) can be replaced by saline solution (0.9 weight percent sodium chloride solution), 

physiological saline solution (sodium chloride plus other minor constituents), synthetic urine, synthetic 

menstrual fluid, synthetic blood or a variety of other liquids. The time of wetting can be controlled by a variety 

of methods, and can also be automated. The time of wetting can usually be determined fairly easily, as the 

droplet tends to show a somewhat different visual appearance and to spread slightly immediately shortly 

before disappearing into the interior of the fabric. 

For those who want a more precise or quantitative method, variations have been used with some success. For a 

pure scientific method, the traditional contact angle of the Lucas Washburn equation is often attempted. 

However, upon study it is soon realized that the scientific contact angle is dependent upon having a smooth, 

pure, uniform surface where the interface of liquid, solid and gas can be assessed. Looking at the surface of a 

nonwoven fabric clearly shows that these requirements are not met. 

Much work has been done on single fiber wetting to substitute for the shortcomings of a fabric surface 

characteristics. This can yield considerable useful information, but it often departs substantially from the 

environment encountered by the drop of liquid on a nonwoven fabric surface. 

One approach to measuring the contact angle of nonwoven fabrics was offered by Cusick and Hopkins 

(Cusick, G.E. and Hopkins, Teresa, INDA Journal of Nonwoven Research, 1, No. 1, pp. 32-34, 1989). This 

method involves an apparatus which holds the test fabric and can be rotated until the meniscus formed by the 

liquid and the fabric "disappears," or the liquid at the fabric surface is level. 

Clearly, a controlled technique is needed that approximates the control, precision and preciseness and 

versatility of the contact angle method, while allowing adaptability to the radically different character of a 

fabric surface. 

A useful adaptation and amalgamation of these desires is afforded by a method described in a U.S. patent that 

was granted a few years ago. The method was originally devised to assess the ability and suitability of a 

nonwoven filter fabric surface to quickly wet out and pass whole blood, such as involved in a blood bank 

collection operation. With suitable filtration, depletion of the leucocytes (white blood cells) in the blood can be 



achieved. These are the cells which have surrounded bacteria, viruses and other blood debris; their removal 

from the collected blood can greatly improve the quality of the blood, and rid it of the normal risk for a 

transfusion patient. 

To be practical, an infusion set-up for injecting the blood into a patient must work correctly every time; a 

blood filter unit that slows or halts the flow of blood from the collection/storage bag into the patient cannot be 

tolerated. The pressure driving the blood flow is modest; only that coming from a height of several inches. 

As a consequence of a need for a quick, definitive laboratory test, the inventors of this patent fashioned a 

modified test method that mimics the utility of the contact angle method, applied to the needs and surface of a 

nonwoven filter medium. Their method is called the "Critical Wetting Surface Tension (CWST)." 

The method involves a series of test solutions having a range of surface tensions. A set of test solutions is 

prepared so that each solution has a surface tension of about 3.0 units different than the other solutions. The set 

of test solutions is prepared so that it covers the range from pure water (73 dynes/cm) to that of a fluorocarbon 

liquid (25 to 30 dynes/cm range). 

The test is carried out by placing 10 standard-sized drops of a test liquid on the surface of the nonwoven fabric. 

A timer is started at that time, providing for a 10-minute time interval. The test drops are observed for letting 

and absorption into the fabric at the end of that time interval. If at least nine of the 10 drops are absorbed 

within the 10-minute test period, it is concluded that the test solution wets the fabric. If less than nine of the ten 

drops are absorbed within the 10-minute time period, it is concluded that the liquid does not wet the fabric. 

Tests are run with the solutions from the set of standard surface tension samples until two test solutions with 

surface tensions separated by no more than 3.0 dynes/cm are identified, the one test solution wetting the fabric 

(giving at least nine out of 10 drops that wet the fabric), and the other test solution not wetting the fabric (gives 

less than nine out of 10 drops that wet the fabric). The fabric wetting performance, CWST, is then calculated 

as the average surface tension of the two identified test solutions. 

While the CWST is not exactly identical with the surface character measured by the critical angle test method, 

it is a very good empirical substitute, and can nicely characterize a nonwoven fabric surface. Such 

characterization can be very useful for many situations. There appears to be a relationship with the CWST of a 

nonwoven fabric and the specific surface energy of the pure polymer making up the fibers of a pure fabric 

(non-blended fibers). Also, the CWST correlates well with the specific surface energies of the pure polymer 

making up fibers in a blended fiber fabric. The presence of fiber finish and other surface treatments, additives 

and modifications that affect the fiber surface can be detected. The importance of surface tensions of the 

participating liquids of the application can also be delineated. 

By using 10 drops of the test fluid, a good average is obtained, even taking into account the non-uniformities 

of a typical fabric surface. The use of test solutions with relatively small differences in surface tension, and the 

averaging of data points also helps to even out any abnormalities and departures from strict test methodology. 

The end result is a versatile, empirical test method that can be very useful in a variety of applications. 

Source: "Device and method for depletion of the leukocyte content of blood and blood components." U.S. 

Patent No. 4,925,572 (May 15, 1990). Inventor: David B. Pall. Assignee: Pall Corporation. 

Kilobytes versus Kibibytes 

A previous issue of INJ (Vol. 7, No. 2; Spring, 1995) featured a table in the Researcher's Tool Box that 

outlined the prefixes to be used for increasing and decreasing orders of magnitude. Thus, for an increase of 10, 

100 or 1,000 times, a simple prefix can be attached to the basic unit to indicate this increase. Similarly, another 

set of prefixes can be utilized to indicate decreasing orders of magnitude. By combining the prefixes with 



scientific units, as specified in the SI System, a considerably simplified and consistent notation system results. 

This system is outlined in the table below. 

10 24 yotta (Y), from Greek of Latin octo (eight) 

10 21 zetta (Z), from Latin septem (seven) 

10 18 exa (F), from Greek hex (six) 

10 15 peta (P), from Greek pente (five) 

10 12 tera (T), from Greek teras (monster) 

10 9 giga (G), from Greek gigas (giant) 

10 6 mega (M), from Greek megas (large) 

10 3 kilo (k), from Greek chilioi (thousand) 

10 2 hecto (h), from Greek hekaton (hundred) 

10 1 deka or deca (da), from Greek deka (ten) 

10 -1 deki (d), from Latin decimus (tenth) 

10 -2 centi (c), from Latin centum (hundred) 

10 -5 milli (m), from Latin Mille (thousand) 

10 -6 micro (m), from Latin micro or Greek mikros (small) 

10 -9 nano (n), from Latin nanus or Greek nanos (dwarf) 

10 -12 pico (p), from Spanish pico (a bit) or Italian piccolo (small) 

10 -15 femto (f), from Danish-Norwegian femten (fifteen) 

10 -18 atto (a), from Danish-Norwegian atten (eighteen 

10 -21 zepto (z), from Latin zeptem (seven) 

10 -24 yocco (y), from Greek or Latin octo (eight) 

With the advent of the computer and its accompanying "computerese," these prefixes have been adopted in a 

similar manner. Thus, everyone knows that a megabyte is one million bytes. And that a gigabyte is a thousand 

million bytes or one billion bytes. The use of this prefix system is so pervasive that the abbreviation system has 

been further abbreviated; thus, everybody knows and can respond appropriately when told that a computer has 

10 "gig" of memory. 

Unfortunately, this system of prefixes applied to the computer situation is not strictly correct. Whereas, the 

normal scientific system or metric is based on 10 digits, called a decimal system, in computer work a binary 

system based on a two-digit code is employed. Therefore, a "kilo" in the binary computer system is actually 

1,024 instead of 1,000 (2 to the 10th power). 

Consequently, the use of the normal metric system prefix is actually incorrect when applied to the computer 

binary system. 

Thus lacking in exactness, two major organizations have adopted new numerical prefixes for numbers in the 

computer binary system. The International Electro-Technical Commission (IEC) is responsible for 

international standards for electronic technologies. With considerable imput from the National Institute of 

Standards and Technology (NIST) in the United States, a new system has been adopted for the binary system. 

Now, to represent exponentially increasing binary multiples, the IEC has designated kibi (Ki), mebi (MI), gibi 

(Gi), tebi (Ti), pebi (Pi) and exbi (Ei). Thus a kibibyte is 2 to the 10th power or 1,024 bytes; a mebibyte is 2 to 

the 20th power, or 1,048,576 bytes; and so forth. 


Standard Development Forum 


STANDARDS DEVELOPMENT 

FORUM 

By Chuck Allen, INDA Technical Director 

Test Method Harmonization 

The buzzword in the area of standardized test methods is harmonization (making test methods the same in different parts of the 

world). As discussed in the last issue of the INJ, there are any number of standards setting organizations worldwide. Each 

organization has its own process for evaluating and adopting test methods. 

One can imagine the technical and political difficulties that could be associated with identical test methods being adopted by two 

or more of the organizations. Having to use different test methods on the same product, depending on where the product is being 

sold geographically, presents difficulties and is costly. Laboratories may need to purchase and maintain different pieces of 

equipment or instruments for testing the same properties of fabrics or products. To be able to generate reliable and reproducible 

results, lab personnel must become familiar and experienced in conducting the applicable test methods from more than one 

standard setting source. 

Almost all the standard setting organizations recognize there is demand for test method harmonization and are investigating ways 

of cooperating with each other to reach this difficult goal. 

Harmonization In Nonwovens: INDA and EDANA have made test method harmonization a high priority. INDA publishes its 

own Standard Test Method (STM) manual, which contains over 50 test methods for nonwoven fabrics. Test methods from the 

STM manual are then moved through the ASTM process, where the goal is to have them all eventually approved as ASTM 

methods, and in the ASTM format. All the currently adopted ASTM Nonwovens test methods, except for the geotextile methods, 

originated as INDA Standard Test Methods. 

Likewise, EDANA publishes a test method manual, EDANA Recommen-ded Test Methods (ERT), containing over 40 methods 

for testing nonwoven fabrics. EDANA works through CEN (European Committee for Standardization) and ISO (International 

Organization for Standards) to have their methods recognized as national and international standards. 

The STM and ERT manuals contain many methods that measure the same properties, but the methods have differences. Due to 

recent correlation activities by the two organizations, there are now five methods that have been harmonized and are identical as 

contained in the INDA STM and the EDANA ERT manuals. 

Work has begun on the next series of five STM and ERT methods scheduled for harmonization. INDA, through the Nonwovens 

Cooperative Research Center (NCRC) at North Carolina State University, has put together a harmonization document, which is 

in its final editing stages; this document lists the differences between INDA STM methods and related EDANA, ASTM, TAPPI, 

ISO and AATCC methods. This document will soon be available through INDA. 

Global Harmonization: INDA and EDANA are not the only ones involved in test method harmonization. In late 1998, ASTM 

and ISO had a meeting to discuss how they could work together more productively. As an outcome, ASTM submitted a pilot 

program for ISO consideration involving ASTM standards used in the global market where there are no ISO counterpart 

standards. ASTM would be the developer and maintainer of the standards and would actively seek input from ISO member 

bodies. The resulting standards would carry an ASTM/ISO designation. 

The proposal has met with approval by the ISO leadership task force and has been presented to the ISO council for final 

approval. At the time of this writing, the outcome is not known, but the vote was expected to take place at the ISO meeting in 

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July. It is important to note that this new system would be on an 

individual test method basis. Any communication and cooperation 

between ASTM and ISO must be considered a step in the right 

direction toward harmonization. 

In Europe, CEN is standardizing methods of its member 

countries, which include Austria, Belgium, Czech Republic, 

Denmark, Finland, France, Germany, Greece, Iceland, Ireland, 

Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, 

Sweden, Switzerland and the United Kingdom. The national 

standard organizations of the member countries are bound to 

implement CEN approved European Standards, either by 

publication of an identical text or by endorsement, and conflicting 

national standards will be withdrawn within a given time period. 

This will result in harmonizing test methods used within all the 

CEN countries. 

As can be seen, test method harmonization activities are taking 

place around the world and are to be applauded. Having global 

harmonization of test methods is a noble goal that will take lots of 

work and even then may not be accomplished in all areas. When 

asked, "Is achieving a single standard practical?" Sergio Mazza, 

president of ANSI replied, "Sometimes yes, sometimes no. To try 

to answer this question out of the context of a specific application 

is completely pointless. In every sector, and sometimes in every 

instance within a given sector, you're going to get a different 

answer. I do believe you can make a general statement of 

principle that you would rather have fewer than more standards, 

that you want to minimize duplication, that you want to minimize 

TANDEC Schedules Conference 

The ninth annual TANDEC Conference will be held 

November 10-12, 1999 at UT Conference Center, The 

University of Tennessee, Knoxville, Tennessee, USA and 

focus on several exciting areas of the nonwovens industry 

and technology: 

● Marketing Analysis of Nonwovens 

● Innovations in Spunbond and Melt Blown Technology 

● Nonwoven Composites and New Applications 

● New Technology Development and Opportunities 

● Fundamental Studies in Nonwovens 

Attendees will receive concise and practical information on 

new nonwoven products and markets, and gain a firm 

understanding of the latest technological advances in 

meltblowing, spunbonding and related processes. 

TANDEC Conferences feature a broad cross section of 

speakers, who combine the best aspects of industry, academia 

and the consulting sphere. Professionals in nonwovens R&D, 

marketing, production and management will benefit by 

attending this conference. For additional conference 

information please meet us in cyberspace at: 

http://web.utk.edu/tancon. For conference schedule: 

http://web.utk.edu/tancon/program.html. For registration 

info: http://web.utk.edu/tancon/registra.html. 

conflict, but in many circumstances you can't eliminate duplication and conflict. You're dealing with different technical 

infrastructures, or different regulatory infrastructures, in each sector, and in different parts of the world. The challenges are 

demanding and the goals are worthwhile. Globalization is not a fad. It is here to stay and there is a need and desire for global test 

method harmonization. " 

FORMALDEHYDE TEST METHOD EVALUATION FOR NONWOVEN PRODUCTS 

Industry Collection Developmement Specific Interference Range Instrument Ease 

Time 

(ppm) 

AATCC Textile Water Nash Yes Yes 10-3500 Spectrom. Easy 

Many/day 

Japanese Japan Water Nash Yes Yes 10-3500 Spectrom. Easy 

Many/day 

HPLC ASTM N/A HPLC Yes No >0.05 HPLC Med. 

Many/day 

Tube Furnace UF/Glass Air/Temp. DNPH/HPLC Yes No >0.05 HPLC Med. 

10-15/day 

Chamber Wood Air/Temp. ? (Yes) (No) HPLC Med. 

Limited 

Humidity 

Head/Space Chemical Air/Temp GC/MS Yes No >25 GC/MS Med. 

8-10/day 

GC/MS 

Hard 

Formaldehyde Measurements 

Considerable effort has been focused on formaldehyde, formaldehyde content, formaldehyde analysis and related problems over 

the past several years. Many concrete and expensive steps have been taken by the Nonwovens industry to ensure compliance with 

a vast array of regulations. 

One of the most positive and helpful activities in this regard has been the TAPPI Binders and Additives Committee work directed 



toward the formaldehyde problem. This committee has carried out an 

aggressive program focused on developing useful facts and technology, 

while dispelling myths and bias. Status reports of this effort were provided 

in 1995 and the results of a Round Robin testing exercise were provided in 

1996. 

This committee recently completed a major phase of their work and has 

provided a definitive status report on the extensive effort expended. This 

report was circulated as a separate paper at the recent TAPPI Technical 

Conference (March, 1999), although it was not presented verbally. This 

summary report was prepared by the three leaders of the Sub-committee 

efforts: Michele Mlynar (Rohm and Haas Company); Tom McNeal (Borden, 

Inc.) and S.J. Wolfersberger (Owens Corning Fiberglas). However, because 

of the seminal nature of the report, wider circulation is certainly justified. 

What follows is an abstract of this report, prepared to provide insight into 

the essentials and conclusions of the report. 

The objective of the "Formaldehyde Testing Task Force" was to review 

available methods for the measurement of formaldehyde for nonwovens, and 

to agree on industry measurement standard. The committee identified three 

areas for formaldehyde measurements related to the nonwoven 

manufacturing process: 

Binders: water-based emulsions, phenol-formaldehyde resins, 

melamine-formaldehyde resins, and urea-formaldehyde resins. 

Stack Emissions: ducts, ventilation systems, venting stacks and other 

process sources. 

Nonwoven Products: formaldehyde content, evolution from disposable, 

durable and industrial nonwoven products. 

Each area was assigned to a committee which reviewed different test 

methods used by various segment of the industry. These various test 

methods were evaluated by establishing test criteria and comparing the 

different methods against these criteria. This report summarizes the 

formaldehyde test methods evaluated for these three different industry 

segments. 

The committee found that a single method cannot be recommended for each 

industry segment, but that several methods can often be considered for each 

segment. This report can be summarized as follows: 

Binders: For water-based emulsions, the ASTM Method (#PS-94-4/#D 

5910-96) and the AC Method (#AC-7) were examined. The ASTM method 

has been approved by ASTM and other groups, performs very well, and can 

be recommended without further evaluation. It is somewhat more complex 

and more expensive. The AC Method is limited to low pH emulsions. The 

ASTM Method is preferred. 

Phenol-Formaldehyde resins were evaluated by three methods (ISO #9397; 

#IR-038-05; #M2221.2), all of which use the same analysis mechanism. The 

methods differ by endpoint pH determination method, inclusion of 

calibration or blank procedures, and certification. All three methods are 

more or less equivalent in their results. The ISO (International Standards 

Organization) Method has industry certification and is the basic 

recommendation.. 

Melamine-Formaldehyde resins were only analyzed by the Method 

ASSOCIATION FORUM 

Oil Spill Cleanup Standards 

Like many complex activities, techniques for 

handling oil spills have been spur-of-the-moment 

and highly empirical. The experience of the last 10 

years has provided some useful guidelines in 

dealing with these calamities, but the technology 

and procedures are far from being well established. 

To assist in moving toward a more rational 

approach to remediating the oil spills and related 

incidents, the American Society for Testing 

Materials (ASTM) has initiated an effort to 

develop oil spill cleanup standards. To that end, 

ASTM is requesting assistance in developing new 

standards for shoreline oil spill cleanup and 

restoration. 

Members of oil spill cleanup cooperatives, 

response teams, oil spill removal organizations, oil 

companies and others are invited to provide input 

for develop of these guidelines. This project is 

under the chairmanship of Dr. Dick Lessard, who 

is Oil Spill Technology Coordinator for Exxon 

Research and Engineering. 

Additional standards are also being prepared for 

subcommittee review, including the selection of 

the appropriate shoreline cleaning techniques and 

the classification of shoreline types, along with 

definition and delineation of cleanup materials. 

Comments in regards to these and other shoreline 

cleanup standards are also invited. 

In view of the fact that meltblown oil sorbants 

constitute one of the major resources for this 

activity, a significant contribution from this 

segment of the nonwovens industry is expected. 

For further information or to participate in the 

preparation of these standards, the ASTM contact 

is Robyn Zelmo, 610-832-9717; Fax: 

610-832-9666; rzelmo@astm.org. 

Cellulose Aging Study 

An interesting research project has been initiated 

by The American Society for Testing and 

Materials (ASTM). This will involve a 

century-long study of the effects of natural aging 

on printing and writing papers. A total of 15 

experimental paper types will be stored in volume 

form by 10 North America universities and 

government agencies. Normal storage conditions 

as encountered in a typical library stack will be 

involved. Samples will be withdrawn from the 

specimens at various time intervals to follow the 

changes with time. A century may seem like a long 

time to wait for results, but it was decided that 

accelerated aging studies need to be cross-checked 



(#ADCH-0188). This method was selected as the resin has a high pH and 

requires initial neutralization, which is provided for in the method. This 

method is very similar to the urea-formaldehyde method, after the 

neutralization step. It is considered to be quite comparable to the UF 

methods. It provides satisfactory results. 

with actual experience. However, the researchers 

who are initiating the project will not be waiting 

around for the results 

Urea-Formaldehyde resins were subjected to four test methods (#ADCH-0184; #M2221.1; #ACDH-0185; A.P.#32), all of which 

were based on the same chemistry. Because of the possibility of unwanted hydrolysis of the resin, the methods are rather 

sensitive to operator technique. All four variations are considered valid and are quite comparable. 

Recommendations for using the methods studied are provided. Suggestions on calibrating the analysis, potential sources of error 

and variation, an indication of precision, etc. are offered for some of the methods. 

Stack Emissions: In this category, five test methods were reviewed, but no recommendations were made, as no Round Robin 

tests have been conducted so far. 

The analytical methods considered included the following: 

Chromotrophic Acid: Samples are collected in impingers, usually with aqueous 1% sodium bisulfite as the impinger collection 

solution. Normally, an EPA Method 5 train is used with a heated filter and probe ahead of the impinger sampling train. Impinger 

samples are analyzed by the chromotropic acid method, forming a purple color proportional to formaldehyde concentration, 

which is measured in a spectrophotometer at a wavelength of 580 nm. 

Dinitrophenylhydrazine Method: Samples are collected in impingers, usually using saturated 2,4,DNPH (dinitrophenylhydrazine) 

in aqueous 2 NHCl as the impinger collection solution. Normally, an EPA Method 5 train is used with a heated filter and probe 

ahead of the impinger sampling train. Impinger samples are extracted with methylene chloride, and the extracts are analyzed by 

liquid chromatography. The chromatographic separation is usually optimized so that a variety of aldehydes and ketones can be 

determined in a single analysis. 

Pararosaniline: Samples are collected in impingers, using high-purity water as the impinger collection solution. Normally, an 

EPA Method 5 train is used (without a filter) and probe ahead of the impinger sampling train. Impinger samples are analyzed by 

the pararosaniline method, forming a purple color proportional to formaldehyde concentration, which is measured in a 

spectrophotometer at a wavelength of 570 nm. 

Fourier-Transform Infrared Spectro-scopy: Measurements are made directly on the stack gas, by passing an infrared beam across 

the stack (in-situ), or by extracting a portion of the gas into a cell. High-resolution infrared spectra are obtained, and interfering 

spectral features (from compounds such as water, carbon dioxide, etc.) are subtracted from the spectra. The amount of 

formaldehyde can then be calculated by comparison to a stored reference spectrum of a formaldehyde standard. 

Acetylacetone: Samples are collected in impingers, using high-purity water or 10% methanol in water as the impinger collection 

solution. Normally, an EPA Method 5 train is used with heated filter and probe ahead of the impinger sampling train. Impinger 

samples are analyzed by the acetylacetone method, forming a yellow color proportional to formaldehyde concentration, which is 

measured at a wavelength of 412 nm. 

It is suggested that Round Robin testing is appropriate in this sector, along with a further study of Head Space/Gas 

Chromotography/Mass Spectography Detection (GC/MS) Method. 

Nonwoven Products: In this industry sector, a total of 10 test methods were submitted and reviewed, including the following: 

AATCC Sealed Jar Test #112-1993: This method is used for nonwovens and other textiles employed in the industry. It measures 

the free formaldehyde plus some of the bound formaldehyde in a fabric. 

Tube Furnace Method: This method is specific for urea-formaldehyde and glass mat products. With HPLC development properly 

carried out, it is very specific for formaldehyde. 

Japanese Ministry Ordinance Article #4, Legislation #112, 1973: This method measures the free formaldehyde in a sample, but 

under some conditions can generate analyte from bound formaldehyde. The method is required for any imports into Japan. It is 

also growing in use as a standard method for the baby wipe industry. 

Chamber Test: This method is used by the wool industry to measure the formaldehyde emission from wool dust particles. It is a 

dynamic test that could be adapted for nonwovens, but required further development work. 



Head Space/GC/MS: Further work is required to assess the value of this method in comparison to other methods. 

LC Pre-Derivatization (High Pressure Liquid Chromatography, HPLC/Nash): This method uses high pressure liquid 

chromatography to separate the free formaldehyde from the other components, followed by post column derivatization with Nash 

reagent and visible absorbence detection. It is a method under development, so is not appropriate at this time for a standard. 

MITI JIS-L1041-1960: This method is the forerunner of the present Japanese Law 112-1993 and has been replaced by the more 

recent method. It is not recommended. 

KCN Method: This method was not recommended and is not being further studied. 

Shirley Institute Test: This test was developed many years ago; it is not recommended and will not receive further work. 

The first six method were subjected to further evaluation and rated for characteristics and appropriateness, as summarized above. 

It is hoped that individuals who have a definite interest in this report and topic will pursue the matter further. For those who 

would like to learn more about this project, or make comments on the report and the committee's activities, or to study the 

material further, a copy of the report can be obtained from Michele Mlynar, Specialty Polymers Group Leader, Fiber and Textile 

Polymers, Rohm and Haas, Research Laboratories, 727 Norristown Road, P.O. Box 904, Spring House, PA 19477; 

215-641-7107; Fax: 215-619-1622; michele_f_mlynar@rohmhaas.com 

Your comments and suggestions regarding this department and the area of standards development are welcome, please respond 

to Chuck Allen, callen@inda.org; INDA, P.O. Box 1288, Cary, N.C. 27513; 919-233-1210, ext. 114, Fax 919-233-1282. 

The editors wish to express their appreciation to Mr. Allen for agreeing to develop and edit this column. 



—INJ 


Patent Review 

PATENT 

REVIEW 


Spunbond Fabrics from Nylon and Polyethylene 

Continuous filament nylon spunbond fabrics are a special category within the spunbond nonwoven 

classification. The fabrics are produced by a process in which molten nylon-66 resin is extruded into 

continuous filaments, the filaments are attenuated and drawn pneumatically, and then deposited onto a 

collection surface to form a continuous filament web. These filaments are bonded together to produce a 

strong, coherent fabric. 

Filament bonding in the case of nylon can be accomplished either thermally or chemically. Thermal 

bonding is accomplished by passing the web of filaments through the nip of a pair of heated calender 

rolls; one of the rolls carries a pattern of elevated points providing discontinuous bond sites resulting 

from the heat and pressure of the calender points. 

Chemical or autogenic bonding can also be employed; in this operation, the web of filaments is 

transported to a chemical bonding station or a "gas house," which exposes the filaments to a mixture of 

hydrogen chloride gas and water vapor. The water vapor enhances the penetration of the hydrogen 

chloride gas into the filaments; the mixture causes the filaments to become tacky and thus amenable to 

autogenic bonding. Upon leaving the bonding station, the web passes between rolls which compact and 

bond the softened filaments in the web. Adequate bonding is necessary to minimize fabric fuzzing (that 

is, the presence of unbonded filaments) and to impart good strength properties to the fabric. Autogenic 

bonding has been especially used in forming spunbond nylon- 66 industrial fabrics. 

Whether bonded by the intermittent thermobond process or autogenic bonding agents, these nonwoven 

fabrics tend to be somewhat stiff and boardy, as produced. This arises from the fact that even with point 

bonded fabrics, it is frequently difficult or even impossible to strictly limit bonding to the desired points. 

Filaments that are not compressed by the embossed points are still subject to the heat of the calender and 

tend to form weak, secondary or "tack" bonds of the filaments outside the desired bond areas. In a similar 

manner in autogenic bonding, secondary or tack bonds can form between filaments where the area of 

contact is very limited, giving weak bonds. 

In both processes, these weak, secondary bonds promote fabric stiffness, but contribute little to fabric 

strength and integrity. Consequently, it has been found beneficial to subject such nonwoven fabrics to a 

file:///D|/WWW/inda/subscrip/inj99_2/patent.html (1 of 8) [3/21/2002 5:05:34 PM]

Patent Review 

softening process. This is generally done by subjecting the fabric to mechanical stress. Such treatments 

are believed to effect softening primarily by breaking the weak, secondary tack bonds, which can be 

broken without breaking the primary point bonds or those bonds intentionally created to foster strength. 

The mechanical stress methods for softening may include the process of washing the fabric, drawing the 

fabric under tension over sharply angled surface such as a knife blade, stretching the fabric, twisting, 

crumpling or subjecting the fabric to various combinations of such treatments. The fabrics can also be 

softened by impinging the fabric with high pressure fluid jets. While these mechanical stress methods are 

relatively effective, they create many problems, especially in view of a desire to maintain a direct, 

continuous process. 

This patent describes a process for obtaining a soft, yet strong nylon spunbond fabric without the 

problems associated with the mechanical stress softening steps. This involves the addition of a small 

amount of polyethylene polymer to the nylon feedstock prior to extrusion. The addition of the 

polyethylene to the nylon resin enhances specific properties such as softness. The use of polyethylene 

also lowers the cost of production and eases further downstream processing, such as bonding to other 

fabrics or to itself. 

The improved nylon spunbond fabric is obtained by adding a small amount of polyethylene resin, 

preferably a linear low density polyethylene resin, in amount of about 0.5 weight percent to the nylon 

feed material. This amount of polyethylene resin does not adversely affect the spinning performance. The 

added PE resin actually improves the throughput by approximately 8%, apparently by fostering the 

passage of the blended resin through the entire spunbonding process. 

The filament extrusion step is preferably carried out at a temperature in the range of 280° C to about 315° 

C. If some nylon-6 resin is added to the feedstock, a somewhat lower extrusion temperature can be 

utilized. Other lower melting polyamides can also be used in practicing the patent. The filaments 

produced with the modified process can be bonded with the thermal point bond method or by the 

chemical autogenic method. 

In a typical example, a blend of 99.5% nylon and 0.5 weight percent linear low density polyethylene can 

be converted into a spunbond fabric at one ounce per square yard basis weight, using an extrusion 

temperature of 300° C. The resulting continuous filament web was bonded at the chemical bonding 

station, using hydrogen chloride gas and water vapor at a temperature of about 39° C. Following 

treatment in the gas house, the web was then subjected to a compacting step in which the web was 

compacted and further bonded. 

The quality of the fabric produced with the polyethylene additive did not differ appreciably from that 

produced without the polyethylene. Furthermore, the process parameters employed in the extruder, filter 

packs, etc., did not change significantly. Spinning performance was similar to that encountered in the 

routine process. The completed fabric was considerably softer than the comparable fabric produced from 

100% nylon-66 and the throughput was increased by approximately 8%. 

U.S. 5,913,993 (June 22, 1999); filed January 10, 1997. "Nonwoven nylon and polyethylene fabric." 

Assignee: Cerex Advanced Fabrics, L.P. Inventors: Ortega, Albert E.; Thomley, R. Wayne. 

Electret Meltblown Webs 

The meltblown process has been used for several years to prepare nonwoven fibrous webs suitable for 

use as filtration media. The webs of microfiber resulting from this process are especially effective in the 


Patent Review 

filtering of particulate contaminates. Consequently, such filter media has been used in face masks, 

respirators, panel filters, pocket filters, bag filters and other devices for the filtering air and liquids. 

The aerosol filtration efficiency of such nonwoven fibrous webs can be improved by imparting an 

electrical charge to the fibers, resulting in the formation of an electret fabric. A number of methods are 

known for forming such electret materials. These methods include, for example, bombarding meltblown 

fibers as they issue from the die orifices with electrically charged particles such as electrons or ions (hot 

charging), charging fibers by means of a corona discharge after fiber formation (cold charging), or 

imparting a charge to a fiber mat by means of carding and/or needle tacking (tribo-charging). Also, the 

use of jets of water impinging on a nonwoven web at a sufficient pressure can provide a filtration 

enhancing electret charge to the web (hydro-charging). Other types of nonwoven fibrous webs useful for 

filtration purposes have been prepared by fibrillating films of polyolefin to form a fibrous material. Such 

fibrillated materials may be charged as the film followed by corona discharge, for example. Following 

fibrillation, the web is collected and processed into a filter. 

The current process discloses a method of making a fibrous electret material particularly suitable for 

filtration applications. The process comprises the steps of forming a fibrous web via the meltblown 

process. A specific chemical agent is added to the thermoplastic polymer prior to conversion into 

microfibers by the meltblown process. Following collection of the web, it is subjected to impinging jets 

of water at a pressure sufficient to provide the web with an electret charge. The resulting web is a 

superior filter medium. 

Thermoplastic resins suitable for use in the process are nonconductive polymers; polypropylene, 

poly-4-methyl-1-pentene resins, blends of these two resins or copolymers formed from propylene and 

4-methyl-1-pentene are preferred as the fiber forming material. The resin should be substantially free 

from materials such as anti-static agents, which could increase the electrical conductivity or otherwise 

interfere with the ability of the fibers to accept an hold electrostatic charges. 

The chemical additive used in the process enhances the electret-forming propensity of the patented 

microfiber web. Two different classes of suitable additive materials are disclosed and the process is 

based on using one or other of the two additives or a combination of the two. 

The one class of suitable additive is based on a perfluorinated moiety having a flourine content of at least 

18% by weight. Such compounds include short-chain tetrafluoroethylene telomers. An additive formed 

from N-(perfluorooctylsulfonyl)-piperazine, triethylamine and phthaloyl dichloride is particularly useful. 

The second class of electret enhancing additive comprises a thermally stable organic triazine compound 

or oligomer containing at least one nitrogen atom in addition to those in the triazine group. Such a 

material can be prepared from N,N -di-(cyclohexyl)-hexamethylene-diamine and 

2-(tert-octylamino)-4,6-dichloro-3,5-triazine. 

The fluorochemical additive or the triazine-based additive is preferably used in the amount of about 0.5 

to 2 weight percent. A blend of the thermoplastic resin and the additive can be prepared by pre-blending 

and pelletizing. Alternately, the additive can be blended with the resin in the extruder and melt extruded 

directly. Extrusion conditions are generally those which are suitable for extruding the resin without the 

additive. 

Microfiber webs from the additive/polymer blend are prepared with effective fiber diameter in the range 

of 7 to 15 microns. Webs having a basis weight in the range of about 10 to 100 gsm are suitable. The 


Patent Review 

thickness of the filter media is preferably about 0.5 to 2 mm. The electret filter medium and the resin 

from which it is produced should not be subjected to any unnecessary treatment which might increase its 

electrical conductivity, e.g., exposure to gamma rays, ultraviolet radiation, pyrolysis, oxidation, etc. 

Hydrocharging of the web is carried out by impinging fine jets of water onto the web at a pressure 

sufficient to provide the web with a filtration enhancing electric charge. The pressure necessary to 

achieve optimum results will vary depending on the type of jet used , the type of polymer, the type and 

concentration of additives, the thickness and density of the web and whether pre-treatment such as 

corona surface treatment, is carried out prior to hydrocharging. Generally, pressures in the range of about 

10 to 500 psi (69 to 3450 kPa) are suitable. An apparatus suitable for hydraulically entangling fibers is 

generally useful in the method of hydrocharging the nonwoven web, although the operation is carried out 

at lower pressures in hydrocharging than generally used in hydroentangling. 

The inventors suggest the technique of measuring the filtration performance of the web before and after 

hydrocharging as the method to determine the effectiveness of electret formation. An increase in the 

filtration performance is indicative of the trapped charge. This can be confirmed by subjecting the treated 

web to a charge destroying procedure, such as exposure to x-ray radiation, alcohol treatment 

(isopropanol) or heat treatment at a temperature about 30 0 C. below the melting point to near the melting 

point and again measuring the filtration performance. 

The inventors point out that staple fibers can also be introduced into the web. Further, sorbent particulate 

material, such as activated carbon or aluminum, may also be incorporated. 

The enhanced performance of the filter media can often be further improved by annealing, i.e., heating 

for a sufficient time at a sufficient temperature to cause the additive to bloom to the surface of the fibers. 

Generally, about one 1 to 10 minutes at about 140 0 C is sufficient for a polypropylene filter medium. 

U.S. 5,908,598 (June 1, 1999); filed August 14, 1995. Assignee: Minnesota Mining and Manufacturing 

Company. Inventors: Alan D. Rousseau, Marvin E. Jones, Seyed A. Angadjivand. 

Lotion Wipe with Inverse Emulsion 

This patent is directed toward a special type of disposable wipe, containing a lotion used to soothe the 

skin. Such a wipe can be a special type of facial tissue or more substantial nonwoven wipe intended for 

multiple uses. Some aspects of the patent disclosure are directed toward personal wipes, such as 

wet-wipes used to cleanse the perianal area, premoistened baby wipes, adult incontinence wipes or as a 

form of premoistened bathroom tissue. 

The performance of such wiping products is enhanced if the wipe releases a significant quantity of water 

during use for comfort and more effective cleansing. Such a wipe is even more effective when a 

controlled amount of a lotion or emollient ingredient is deposited. In the case of both liquids, however, 

the quantities involved must be controlled, as an excess of either the water or oil is unacceptable. 

This patent discloses the use of a high internal phase inverse emulsion applied to a nonwoven substrate to 

give a superior wiping product. This type of an emulsion is referred to a regular emulsion, since the 

system consists of a discontinuous water phase dispersed in an emulsion of a continuous oleophilic 

phase. Emulsions that are normally encountered consist of the water phase being the major and 

continuous component, with a small amount of the oil or lipid phase dispersed as emulsified particles 

within the water phase. Such an inverse emulsion can have much of the physical character of the major 


Patent Review 

lipid component. 

The inventors disclose that the lipid phase of an appropriate inverse emulsion employed in the disclosed 

wipes is sufficiently brittle so as to be easily disrupted by low shear contact or compression, such as 

would occur during the wiping of skin. When the lipid phase is thus disrupted, the inverse emulsion 

readily releases the internal water phase. During the rigors of processing the dure manufacture, the lipid 

phase is sufficiently tough at elevated temperatures as to avoid premature release of the water phase 

during such processing. The continuous lipid phase is also sufficiently stable during storage so as to 

prevent significant evaporation of the internal water phase. 

The normal tensile strength and flushability properties of these wipes are not adversely affected when 

treated with the high internal phase inverse emulsion. As a result, users of these wipes get a comfortable, 

efficient, moist cleansing action without having to change their normal cleaning habits. Consequently, 

this technology is readily useful for other purposes such as cleaning hard surfaces, etc. 

The inventors disclose that they unexpectedly found that a continuous coating of the emulsion on a 

substrate does not provide the most efficacious cleaning, particularly when it is desired to clean human 

skin. A discontinuous pattern of the emulsion on the substrate provides a cleaning mechanism not found 

in the prior art. The optimum discontinuous pattern of emulsion is a pattern having regions of the 

substrate free of the emulsion adjacent to zones of the substrate upon which the emulsion is disposed. 

The inventors further discovered that during cleaning, water is released from the emulsion to remove dirt 

from the skin. The area of the skin wetted by the water and from which dirt is removed is then wiped dry 

with the adjacent regions of the nonwoven wiping substrate that are free of the emulsion. Thus, the wipe 

consists of treated zones which release the cleansing water and a small amount of oil, followed by the 

untreated zone of the wipe which picks up the excess water, leaving the skin in an ideal condition. 

The mechanism to release water from the emulsion to the surface to be cleaned involves several steps. 

First, the water is released or expressed from the emulsion due to the pressure imparted by user. The 

pressure ruptures the emulsion, freeing the water. The water then saturates the nonwoven substrate. Upon 

saturation, the water penetrates the nonwoven substrate in the Z direction. Excess water, which is that 

water in excess of the local absorbent capacity of the substrate, is then transferred from the wipe to the 

surface. As the surface is contacted by the untreated zone of the wipe, the cleansing water is removed. 

The inventors claim that similar benefits occur when the wipe is used to clean other surfaces, such as 

window glass, counter tops, sinks, porcelain and metal fixtures, walls, and the like, as well as from other 

surfaces, such as carpeting or furniture. 

The patent discloses that a preferred embodiment of the invention involves a nonwoven substrate 

comprising high and low basis weight regions. The emulsion is positioned in the low basis weight 

regions. This provides a further differentiation of the dispensing zone of the wipe followed by the higher 

density absorbing zone, providing a multi-functional wiping substrate with a superior performance. 

The emulsion comprises: (1) a continuous solidified lipid phase; (2) an emulsifier that forms the 

emulsion when the lipid phase is fluid; and (3) an internal polar phase dispersed in the liquid phase. This 

emulsion ruptures when subjected to low shear during use, for example, wiping of the skin or other 

surface so as to release the internal polar phase. Preferably, the lipid phase will comprise from about 6 to 

15% of the emulsion. The major constituent of this continuous liquid phase is a waxy lipid material with 


Patent Review 

a melting point in the range of about 50 to 70 0 C. Although this waxy lipid material is solid at ambient 

temperatures, it also needs to be fluid or plastic at those temperatures at which the high internal phase 

inverse emulsion is applied to the substrate. The major component of the high internal phase inverse 

emulsion is the dispersed internal polar phase which consists of water, comprising about 85 to 94% by 

weight. 

The inventors point out that a wide variety of materials can be combined with the ingredients of the 

inverse emulsion, such as emollients, medicaments, bleach, surfactant, solvents, disinfectants, chelating 

agents and others. 

Suitable substrates to be with this wipe can be of various types. Nonwoven fabrics, particularly those 

with regions of low and high density are particularly useful. Also, the nonwoven fabric can be apertured 

to provide an extreme case of density differentiation. Airlaid pulp webs and wetform webs can be 

employed, along with various types of tissue products. 

A variety of patterns for application of the inverse phase emulsions are suggested by the inventors. The 

emulsion can be employed in stripes, which affords coated regions adjacent to non-coated regions in the 

final wiping product. Also, a variety of other patterns can be employed, including patterns which involve 

topic designs suitable for aesthetic enhancement. 

U.S. 5,914,177 (June 22, 1999); filed August 11, 1997. "Wipes having a substrate with a discontinuous 

pattern of a high internal phase inverse emulsion disposed thereon and process of making." Assignee: 

The Procter & Gamble Company. Inventors: Charles Zell Smith, III, Steven Lee Barnholtz, David 

William Cabell. 

Superfine Microfiber Nonwoven Web 

Microfiber webs, such as meltblown fiber webs are well known and have found application in a wide 

variety of industrial, consumer and medical products. Despite the use and utility of these webs, there is a 

continuing quest for fiber webs containing even finer microfiber. For many applications, the finer the 

fiber, the greater the performance enhancement. 

There have been various attempts to reduce the diameter of meltblown fibers by a variety of methods. 

One such approach is to reduce the polymer through-put to the die head. However, this direct approach 

can only be used to reduce the fiber size to a limited extent, since increasing reduction in the resin 

through-put eventually interrupts the fiber production altogether. 

Another method that has been attempted to produce superfine meltblown webs involves producing 

bicomponent conjugate meltblown fibers of the island-in-sea configuration and then dissolving the sea 

component. This does produce microfibers, but the dissolving process is a distinct disadvantage; 

consequently, this method is uneconomical and inefficient, and so it is seldom used. 

Hydro-needling has been attempted to produce superfine microfibers. This involves the use of 

pressurized jets of water to split multi-component conjugate fibers. While this method is applicable to 

some nonwoven processes, it has not been used to produce split meltblown fiber webs, since the 

autogenously bonded meltblown fiber webs are quite weak and contain a numerous interfiber bonds that 

restrict fiber movements; consequently, these webs are very difficult to split with a mechanical splitting 

process without substantially destroying the web. 

The present invention provides a web containing superfine microfibers. This web is produced from 


Patent Review 

side-by-side bicomponent fibers produced by the meltblown process. The characteristics of the 

components of such bicomponent fibers must be carefully selected in order to produce an effective 

superfine microfiber web that can be easily split. The two polymer components must be incompatible, so 

they have a fairly substantial propensity to split. One polymer component must be a hydrophobic resin, 

whereas, the second polymer component must be a hydrophilic resin. 

The hydrophobic resin can be a polyolefin resin such as polypropylene or a processable polyethylene. 

Also, polyethylene terepthalate is a suitable hydrophobic resin. 

The hydrophilic resin can be one of a variety of resins. The suitability of the hydrophilic polymer 

component can best be evaluated by determining the contact angle of the polymer. This is done most 

conveniently by a standard test (ASTM D724-89) performed on a film produced by melt-casting the 

hydrophilic polymer at the temperature of the die head that is used to produce the split microfiber web. 

The "initial contact angle" is determined, by measuring the contact angle by the test method within five 

seconds after application of the water drop to the test film specimen. The film must have an initial 

contact angle less than 80 degrees, and desirably, will have an initial contact angle less than 50 degrees. 

Inherently hydrophilic polymers such as copolymers of caprolactam and alkylene oxide diamine, as well 

as a range of copolymers of poly(oxyethylene) with various base polymers can be used. 

In addition, it is possible to hydrophilically modify polymers and convert them into modified polymers 

having suitable initial contact angle. Thus, a variety of modified copolymers of polyolefins, a wide 

selection of copolymers and other variations can be used for the hydrophilic component. This can be 

done most conveniently by utilizing a surfactant in a hydrophobic polymer to convert it to a wettable 

polymer suitable for use as the hydrophilic component. Fugitive surfactants, that is surfactants that wash 

off from the fiber surface, are suitable for some applications. For other applications, more durable 

surfactants may be used to convert a hydrophobic polymer into a suitable hydrophilic component. The 

amount of surfactants required and the hydrophilicity of the modified fibers will depend upon the type of 

surfactant and the type of polymer used. Typically, the amount of surfactant suitable for the wettability 

treatment is in the range of from about 0.1% to about 0.5% based on the weight of the polymer 

composition. 

The splitting of the bicomponent fiber into superfine microfiber components is carried out by contacting 

the fibrous web with a hot, aqueous split-inducing medium. Such split-inducing media include hot water 

at temperatures preferably between 65 and 100 0 C. Additionally, suitable split-inducing media comprise 

steam, and mixtures of steam and air that have a temperature higher than 60 0 C, but lower than the 

melting point of the lowest melting polymer of the conjugate fiber. This prevents inadvertent melting of 

the polymer component during the fiber splitting process. 

It is suggested that the aqueous spilt-inducing medium exerts an influence, such as swelling of the fiber 

surface of the hydrophilic component. Such reaction to the aqueous medium, and especially surface 

swelling, greatly assists in the fiber splitting operation. 

A variety of particularly desirable pairs of incompatible polymers useful for the present conjugate 

microfibers are provided. In each case, the aqueous inducing medium causes the conjugate fiber to spit 

into the superfine components. The patent points out that such splitting can be achieved in less than one 

second, so that splitting is nearly instantaneous. 


Patent Review 

A variety of suitable configurations for the conjugate fibers can be employed. This includes side-by-side 

configurations, wedge configurations, hollow wedge configurations and sectional configurations. 

Asymmetric geometry for the cross-section can be used provided that it is not occlusive or interlocking. 

U.S. 5,935,883 (August 10, 1999); filed October 23, 1997. "Superfine microfiber nonwoven web;" 

Assignee: Kimberly-Clark Worldwide, Inc. Inventor: Richard Daniel Pike. 

This patent review was compiled courtesy of Smith, Johnson & Associates, a well-known nonwovens 

consulting firm that publishes a monthly patent newsletter, Nonwovens Patent News. 



—INJ 


Worldwide Abstracts and Reviews 


ASSOCIATION FOCUS 

TAPPI Playing Growing Role 

In Nonwovens Industry 

A concerted cooperative effort between the two U.S. associations most involved in the nonwovens 

industry - INDA, Association of the Nonwoven Fabrics Industry, and TAPPI, the Technical Association 

of the Pulp and Paper Industry — has one goal in mind: increasing the knowledge base of the nonwovens 

industry. 

While INDA, by its very nature, has always focused on nonwovens issues, TAPPI has concentrated on 

this specialty business through its Nonwovens Division, one of 12 technical divisions that reports to the 

association's Technical Operations Council. TAPPI, one of the oldest technical associations of pulp and 

paper and allied industries in the world with more than 30,000 members in 80 countries, sees itself as 

playing a very special role of bridging the gap in the area of technology and marketing information 

between the paper industry and the nonwovens industry, according to Nonwovens Division chairman 

T.W. Singh, of Evanite. 

"There seems to be a synergy in process technology and testing methods in the paper industry and 

nonwovens, especially wet laid nonwovens," said Singh. "There has been quite an encouraging level of 

cooperation between TAPPI and INDA over the last few years. Changes in leadership, both in the TAPPI 

and INDA organizations, have helped foster collaborative efforts." 

The most obvious result of increased cooperation between the two associations is the joint INDA/TAPPI 

International Conference scheduled for September, 2000 that is basically a bringing together of INDA's 

annual INDA-Tec meetings and TAPPI's annual Nonwovens Conference. "This joint effort is expected to 

offer the best of both the organizations to their membership, namely market and technical expertise that 

no other technical organization in this field can provide," Singh said. "It will surely eliminate redundancy 

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of activities in the technical and 

marketing fields at a time when cost 

consciousness is an increasing 

concern." 

Six different TAPPI Nonwovens 

Technical Committees (see chart on 

the next page) undertake tasks ranging 

from technical information papers, 

such as the report on various fibers 

used in nonwovens by the Fiber 

Committee, to test methods on fiber 

mats. The Building and Industrial Mat 

TAPPI Staff Contacts 

Charles Bohanan 

Technical Operations Manager, 

770-209-7276; 

Fax 770-446-6947; 

cbohanan@tappi.org 

Carol Mitchell 

Technical Operations Assistant, 770-209-7267; 

Fax 770-446-6947; 

cmitchell@tappi.org 

Committee is working with the EPA on defining relevant test methods for measuring volatile organic 

compounds, and the Binders and Additives Committee is conducting research on formaldehyde emission 

testing. The TAPPI Nonwovens Division also continually revises current publications and writes new 

ones like a "Primer" or "Nonwovens" in text format. 

Singh and others involved with TAPPI Nonwovens see the division's role growing as a result of its 

collaborative efforts with INDA. "Our long-term plan is to continue to work closely with INDA on 

projects of common interest, especially those involving new membership in this industry," Singh said. 

One area of growth is at the membership activity area, where, he added, "we would like to see more 

student and entry-level personnel participate in our activities." 

In the near-term, "Our goals are to include more practical information in the conferences and short 

courses so that attendees may find it more applicable to their daily lives and careers," Singh added. "We 

also intend to assist potential new authors and presenters to improve the quality of their technical 

presentations by utilizing new skills and state-of-the-art audio/video support." 

Sounds like the beginning of a beautiful friendship. 

TAPPI Committee Information 

— INJ 

Building and Industrial Mat Committee: To facilitate the exchange of information concerning the 

manufacture and use of wet-laid nonwoven mat, using fiberglass and other synthetic fibers for industrial 

and building products applications. Charles Diller, 419-878-1151; Fax 419-878-1297; dillerc@jm.com 

Nonwovens Binders and Additives Committee: To facilitate the exchange of useful information on the 

technology and use of products that relate to or are based on continuous webs made from cellulose, 

synthetic and inorganic fibers which have been formed or treated with binders and additives that impart 

specific properties. James Tanger, 704-587-8250; Fax 704-587-8117; tangerj@basf.com 

Nonwovens Fibers Committee: To promote the understanding and knowledge of the fibers used in the 

production of nonwovens and the materials and technologies used in making such fibers. Irwin Hutten, 

912-783-3200; Fax 912-783-3292; hutten@hom.net 

Nonwovens Filtration Media Committee: To facilitate the exchange of information on the technology 



and usage of nonwovens media in filtration. To develop industry test methods in the area of nonwovens 

filtration materials. To define and disseminate terminology and tests with regard to nonwovens 

filtration. To encourage and educate the industry in wider use of nonwovens materials in filtration 

applications. Joginder Malik, 608-873-2476; Fax 608-873-2434; jmalik@nelsondiv.com 

Nonwovens Process Technology Committee: To facilitate the exchange of information on the 

processing and the equipment used in the production of nonwovens. Larry Wadsworth, 423-974-6298; 

Fax 423-974-3580; lwadswor@utk.edu 

Nonwovens Properties and Performance Committee: To facilitate the exchange of information on the 

equipment, methods, procedures, literature and software used in the structure, characterization, 

computer modeling and performance of nonwoven products. Michael Nijakowski, 419-878-1550; Fax 

419-878-1116; miken@jm.com 

TAPPI Nonwovens Division Chairman: T.M. Singh, 541-753-0342; Fax 

541-753-0343;tmsingh@evanite.com 

Vice Chairman: Peter D. Wallace, 828-584-3800; Fax 828-584-3885; wallacepd@bordenchem.com 

Secretary: Norman Lifshutz, 978-448-3311; Fax 978-448-9342; nlifshut@hovo.com 





THE 

NONWOVEN WEB 

ORIGINAL PAPER/PEER REVIEWED 

For the nonwoven scientist and technologist, the Internet has become a virtually unlimited source of 

information. Imagine having access to the memory and storage facilities of several million computers all tied 

together. While the potential is extraordinary, the process of finding a specific piece of information can be 

difficult, tedious and frustrating. 

It's a little bit like stepping into the middle of a very large library, looking around at the books and resource 

materials and then trying to find the needed information without the help of a librarian or a catalog system. As 

one specialist has put it, "It can seem like a library catalogued by a madman." 

Fortunately, there is some help available. One of the most common and best known is the "search engine." 

These are computer programs and systems designed to be given an assignment, and then go out throughout the 

web and retrieve the needed information. Unfortunately, even the most popular search engines can cover only 

a fraction of the indexable web. One fairly recent study (Lawrence S.; Giles, C. L.; "Searching the worldwide 

web," Science, 1998, pp. 280-98) concluded that popular search engines cover less than one-third of the 

indexable web. Since that study was made in 1998, the web has grown even larger; consequently, that figure is 

undoubtedly too optimistic. 

So what does the Internet user do to take full advantage of the potential? The best approach appears to be to 

understand the system and the tools, and then to select the appropriate tool and methodology for the particular 

search or query. This can look like a daunting task, but it is manageable. Not everything has to be learned at 

once and use of the facility does provide greater understanding and appreciation of what is available and a 

knowledge of the most effective ways to procure the information desired. 

Also, as a practicality, it is not necessary to understand and gain experience on all aspects of the web. By 

focusing on those resources that are pertinent to the nonwovens industry, the task becomes more manageable 

and reasonable in scope. 

What follows may be of some help. 

The Internet is basically a great number of computers linked together. These computers are called "servers." 

When you ask your computer (called the "client") to go get information from another computer, the client 

sends out a request over your modem or net connection to a server. What it finds and brings back depends on 

what you asked for, what application or system you used to form the request, and the search system utilized. 

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INDA'S WEB SITE UPDATED 

INDA's web site - www.inda.org - has expanded to include a Job Mart and Classifieds section. The Job Mart 

(www.inda.org/class/jobmart.html) provides a listing of employment opportunities relevant to the nonwovens 

industry. Classified advertisements (www.inda.org/class/) list a service or product a company either needs or 

offers. 

The Job Mart is broken down into six sections: Management, Marketing, Sales, Technical, "Situations 

Wanted" and Post a Job. Classified Advertisements are broken down into Partnerships and Business 

Ventures, Recyclable Materials (Wanted and For Sale), Used Machinery and Equipment, Miscellaneous and 

Place Your Classified Ad. 

Also new to INDA's web site is the industry links page. There are links to other associations, organizations 

and companies related to the nonwovens area. Members of INDA can be linked to the INDA web site free of 

charge. Exhibitors at Filtration '99, Suppliers' Showcase '99 and IDEA 2001 can also have their websites 

linked to INDA's website. 

If a web browser was used to carry out the search, your computer is going to ask a web server to bring back a 

piece of data in form of an HTML (HyperText Markup Language) file. If you used an e-mail application, your 

computer connects to an e-mail server and brings back e-mail. 

The Internet is really made up of several different ways of communicating with servers. Those methods of 

communication are called a "protocol." The many different potential protocols involved break down to a 

selected few, such as the following: 

● Web: hypertext transfer protocol (html) 

● News Groups: news transfer protocol 

● FTP: file transfer protocol 

● Gopher: specific protocol 

● Telnet: specific protocol 

● e-mail: e-mail communications 

So, the Internet is really made up of these elements; everything else is sort of a derivation of these basic 

components. Consequently, it is apparent that the search engine or browser employed for a search controls to 

quite a degree the type of computer files that will be searched. 

In setting up a web site, the webmaster has the opportunity to insert a variety of keywords which identify the 

type of information that will be stored in the site. Some search engines are designed to go out and scan these 

keywords for a match with the keywords contained in the query. A well-designed search engine does not start 

with an empty plate as the search commences, however. Such a server will store the keywords from previous 

searches and consequently will have a sizeable database on which to draw, in order to shorten the search. 

A LOOK AT VARIOUS SEARCH ENGINE 'HITS' 

Search Engine Address (http://www.) Number of Hits Remarks 

AltaVista altavista.com 5,581 

All-purpose engine, but can be good for specific 

searches, as it has a large database and surveys 

large portions of web. 

America Online aol.com 1,223 Popular, but general purpose. 



Beaucoup beaucoup.com 240. 

DejaNews deja.com Primarily for news items; limited for other uses. . 

DogPile dogpile.com 2 

Meta-search engine, which uses other engines to 

do simultaneous searching. . 

Euroseek euroseek.net 1,160 Focus on European portion of the net. . 

Excite excite.com 1,152 An all-purpose engine. . 

Google google.com 2,758. 

HotBot hotbot.com 1,080 

Can use common language; Can specify results 

by date, domain, links to an URL. . 

InfoSeek infoseek.com 2,073 

A hybrid search engine that combines 

staff-reviewed sites with search engine results. . 

Jeeves ask.com 44 

Fair; is a Meta-search engine; in this search it 

used Yahoo, Altavista, Webcrawler, Infoseek and 

Excite. . 

Lycos lycos.com 6 

Netscape netscape.com 9 Web browser. 

NonwovensWeb nonwovensweb.com 1,344 Industry specific; building database. 

NorthernLight northernlight.com 20,033 

Not very discriminating; has a special collection 

of 2 million articles from many sources. ; 

Profusion profusion.com 135 Meta-search engine; 

CNet cnet.com 1,260 

Snap snap.com 1,200 

WebCrawler webcrawler.com Meta-crawler. 

Yahoo yahoo.com 62 Good for broad topic search 

As a practicality, a search engine can shortly become much more expert and efficient in searching broad topics 

of a similar nature. Consequently, some search engines are more useful in dealing with certain topics than with 

other topics. 

Other search engines are designed to utilize a different search strategy. In some cases the search engine goes 

out and utilizes the searching capability of half a dozen other search engines, bringing back the results of their 

searching as an answer to the original query. Naturally, the quality of such a search is dependent upon the 

specific slave search engines employed. 

Also, it should be realized that the nature of searching on the Internet generally results in a substantial time 

delay. When a new website is established, it takes time to be incorporated into the database memories of the 

popular search engines. It has been estimated that it takes about six months for a new web site to be so 

incorporated and to be used in subsequent searches. Consequently, newly constructed sites may be ignored for 

several months. 

All of this points out another fact of life that should be recognized in organizing a search. This was highlighted 

in a recent study published in the scientific journal, Nature (June 1999). This study revealed that the amount of 

information being indexed by the commonly used search engines is increasing, but it is not increasing as fast 

as the amount of information being put on the web. Unfortunately, this means that the explosive rate at which 

information is being placed on the web may actually result in more information being lost to easy public view 

than is made available. 



This more-recent study found that most of the major search engines now index less than 10% of the web. 

Thus, even by combining all the major search engines, less than one-half of the web has been indexed. 

Unfortunately, the mushrooming size of the web creates a substantial gulf between what is on the web and 

what is retrievable. 

The following table reveals how much of today's 

searchable web content is actually handled by a variety of 

search engines. 

NorthernLight 16.0 

Snap 15.5 

AltaVista 15.5 

HotBot 11.3 

Microsoft 8.5 

Infoseek 8.0 

Google 7.8 

Yahoo! 7.4 

Excite 5.6 

Lycos 2.5 

Euroseek 2.2 

Also, the nature of searchable sites is changing rather 

rapidly. As might be imagined, the commercial home 

page sites are growing at a faster rate than other types. At 

the present time, commercial sites comprise about 82% of 

the total. 

The actual breakdown as revealed by this recent study is 

as follows: 

Commercial sites 82.1 

Science/Education 6.0 

Health 2.8 

Personal 2.3 

Societies 1.9 

Pornography 1.5 

Community 1.4 

Government 1.2 

Religion 0.8 

In the last issue of INJ a report from the UK gave an 

indication of the number of "hits" obtained through the 

BOOK REVIEW 

New Nonwovens Textbook 

"Nonwoven Textiles," Oldrich Jirsak, Technical 

University of Liberec, Czech Republic, and Larry 

Wadsworth, TANDEC/University of 

Tennessee-Knoxville, USA, 128 pages 

For decades there has been a demand for a 

comprehensive, well-structured introductory 

textbook covering nonwovens. This new book not 

only fills this need for academia, but will also have 

strong appeal to many other readers. Those in the 

nonwovens industry will find it to be a handy 

reference for areas outside of their specialty. 

Further, the numerous descriptions and process 

schematics will prove useful as reference materials 

for sales professionals and others who must 

explain nonwoven technologies to those outside 

the industry. 

According to Dr. Wadsworth, the text was 

developed based on lecture notes and experience 

teaching numerous nonwovens courses. The two 

major sections of the book deal with raw materials 

for nonwovens and the various production 

technologies. The authors have been careful not to 

overwhelm the reader, striking an appropriate 

balance between breath and depth of coverage. 

Available from: Carolina Academic Press, 700 

Kent Street, Durham, NC 27701, USA; 

Phone:(919) 489 7486, Fax: (919) 489 5668; 

cap@cap-press.com. $39.95 plus $4.50 shipping 

and handling in the U.S; international please call 

for rates. 

use of various search engines that had been given the assignment to search on the term "nonwovens." On the 

previous page is a similar listing done during the month of August, 1999 from a location in the U.S. While the 

number of hits does provide some basis for quantifying the specific search capabilities, a little experience 

shows that this is not completely reliable. Also, this sampling revealed that the most recent additions indexed 

by the network were generally the first items gathered by the various search engines. 

The existence of a search engine reputedly designed specifically for searching items of interest to the 



nonwovens industry is encouraging. This site, NonwovensWeb (http://www.nonwovensweb.com), has made a 

start in indexing items of interest to the industry. Most of the sites are of a commercial nature, but that is 

understandable, in view of the predominance of commercial sites. As further experience and searching time is 

logged, this site will hopefully improve and provide a very useful resource for the industry. 

In considering search resources, other possibilities should not be ignored. There are a vast number of 

dictionaries, encyclopedias, directories and similar types of databases that are now available online. Also, the 

contents of published books can be a very useful source of information, although this may be more difficult to 

dig out for older works. The contents of technical journals are finding their way onto the net very rapidly. 

Some of this can be accessed by the use the index of contents of these various journals. There is frequently a 

charge for obtaining copies of the entire paper. 

Commercial databases have traditionally been a strong source of some types of information. Such commercial 

databases are particularly strong in the area of publications, patents, competitive information and market 

information. 

Trade associations, trade publications and similar sites also can be very useful resources for the information 

search. 

As indicated, skill and facility in the search for nonwovens information is greatly benefitted by regular use of 

the net and experience gained at the keyboard. 

Nonwoven Search Resources 

The following websites are suggested as useful resources for an individual seeking information on nonwovens 

technology and the nonwovens industry. Recognize that some sites are updated regularly, whereas other sites 

receive little attention after the original construction. 

Also, the INJ editorial staff welcomes suggestions from our readers as to useful and innovative websites. 

Sharing your experience makes it doubly meaningful. 

Useful Sites For 

Nonwovens Searching 

• American Filtration & Separations Society: Comprehensive site including membership, conferences and 

educational services, AFS publications, corporate members, Distributors and manufacturers, AFS officers, and 

local chapters. http://www.afssociety.org 

• American Society for Testing Materials (ASTM): Testing methods and standards for materials. Site has a 

directory of testing laboratories and consulting services according to geography and specialty. (Consultant 

listing: www.astm.org/consultants/NEW/index.html) ; 

http://www.astm.org 

• AMTEX: The American Textile Partnership is a collaborative research and development program among the 

industry, the Department of Energy, the DOE laboratories, other federal agencies and universities. The site 

offers a variety of textile items. http://apc.pnl.gov:2080/amtex.html 

• Association of Operating Room Nurses (AORN):. Professional society of perioperatiave nurses. Includes a 

variety of features about association and professional activities, product and services, referral services and 

consultation services. (The association also has a site with links to consumer-oriented information about 

surgery: www.aorn.org/patient) www.aorn.org/ 

• Cotton Incorporated: Home page of cotton producers, including importer database, cotton market economic 



letter, agricultural research, fiber processing research, textile research and implementation, fiber quality 

research, 1995 crop reports, corporate research. Twenty pages devoted to "Cotton For Nonwovens: A 

Technical Guide." http://www.cottoninc.com 

• EDANA: European Disposables and Nonwovens Association. This site comprises an excellent resource. 

Coverage includes EDANA organization, membership, standards development and test methods, events, news 

and publications. A particularly effective description of nonwoven processes is provided, with very good 

schematics. Although not operative as yet, links to other sites are promised. http://www.edana.org 

• Fiber Economics Bureau: The activity of the American Fiber Manufacturers Association concerned with 

fiber economics. An excellent site, with FTC Fiber Rules, Suppliers Guide, Fiber Tariffs, World Directory, 

Fiber History, Polymer Science and numerous links to other related sites. Added FiberWorld Classroom, with 

educational material, some of which is downloadable. Also, a good source of news on the fibers industry. 

http://www.fibersource.com; http://www.fiberworld.com 

• Industrial Fabrics Association International: Association of international industrial and techical fabrics and 

textiles. Site includes membership information, market research, worldwide offices, government affairs, 

technical services, etc. http://ifai.org 

• INDA, Association of the Nonwovens Industry: Items include technical papers, standard tests, conferences 

and exhibitions, publications. Newly added is section on Academic Research Facilities Database; Industry 

links; International Nonwovens Journal, with order form; Job Mart and Classified Ads. http://www.inda.org 

• Machinery Database: TEXDATA five-language database allows machinery manufacturers to provide 

listings on new machinery, replacements and plant modernization. Listing of many machinery categories. Also 

provides for a company search and information, product categories and searching capability. Includes selection 

of nonwoven machinery, comprising web forming, auxiliary machinery. Has short list of technical papers. 

Sponsored by Swiss textile publishing firm, ITS Publishing. http://www.texdata.com 

• Pira International: A global knowledge provider. Items include: membership information, conferences and 

training, publications, and the Pira Database, including a free trial. http://www.pira.co.uk 

• Textile Dictionary: Alphabetical listing of textile features and uses. Managed by the Centre for Canadian 

Fashion & Design. http://www.ntg-inter.com/ntg/textile.htm 

• Thomas Register: Extensive database on products and services, companies, and locations, covering all of the 

USA. www.thomasregister.com 

• U.S. Government: Provides a powerful set of search tools that look for information on the official 

government web sites. Also has information on material in the National Technical Information Service (NTIS). 

http://www.usgovsearch.com 

—INJ 






WORLWIDE ABSTRACTS AND REVIEWS 

A sampling of Nonwovens Abstracts from Pira International: 

A unique intelligence service for the nonwovens industry 

These pages feature an extract from Nonwovens Abstracts, compiled by Pira International, from 

international business journals, newspapers, market research reports and conference proceedings, 

keeping you up-to-date on the latest business and technical developments in the nonwovens industry. 

Nonwovens Abstracts provides international coverage on all aspects of nonwovens production: fibers, 

raw materials, web formation, bonding and converting. Information is also provided on all the different 

nonwoven products, from composites to cleaning materials and the companies and markets involved. 

A monthly journal is available and readers can also access the information from the Paper, Printing and 

Packaging Database on CD-ROM, updated quarterly. The information is available online via the major 

hosts and from the Pira Database on Pira's website - www.pira.co.uk. The web and online databases are 

updated weekly. Pira can provide full text copies of documents cited in the Pira Database and the 

associated abstracts journals. The full text will normally be in the language of publication. 

For a sample journal, a free trial of the web database or more information, please contact the 

Information Center, Pira International, Randalls Road, Leatherhead, Surrey KT22 7RU, UK. Fax: 00 44 

(0)1372 802239 or email: infocentre@pira.co.uk 

For this particular selection, non-English language publications were reviewed in an effort to provide 

coverage of relatively less accessible sources to a large portion of the INJ audience. 

Microbial control finish 

Toray Industries of Tokyo, Japan, have reported on their "Makspec" fabrics - polyesters with a microbial 

control finish. The principal bacteria are methicillin-resistant staphylococcus aureus (MRSA), klebsiella 

pneumoniae, staphylococcus aureus, pseudomonas aeruginoza and escherichia coli. The fabrics have 

been test washed for 15 minutes at 85 o C 100 times and antibacterial high performance is maintained. The 

outer fibre portions are penetrated by the active agent, a method improving on surface adherence and 

kneading into inside fibres in production. Finishing and dyeing methods are the same as for normal 

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polyester fabrics. MRSA and E. coli 0-157 protection is 3-5 times higher than other products. Toray 

plans further healthcare developments and anticipates Japanese sales of 4.5m metres within three years. 

(1 fig). 

Author: Anon 

Source: New Mater. Jpn 

Issue: Jan. 1999, pp 10-11 

Finding your solution 

Nonwoven panels, especially needle penetrable panels, sometimes referred to as tapestry, are discussed 

in a question and answer format. These panels can be based on synthetics, viscose or wool fibres, and 

various surface effects can be obtained, e.g. bright or matt, smooth, fleecy, and also hot or cold tones. 

With synthetics, luminescent effects can be obtained. Needle penetrable panels are relatively new and are 

not yet widely used, partly because the machines required for their production are not always available. 

Author: Aleksandrova M 

Source: Text. Ind. 

Issue: No. 1, 1998, pp 17-19 (In Russian) 

Honshu Kinokurosu - Material supplier for two wipe fields, kitchen paper and wet hand towels 

Honshu Kinokurosu's dry pulp non-woven "Kinokurosu" is mostly used for wipes, in particular kitchen 

paper and wet hand towels. Lion's kitchen paper, made of Kinokurosu, has been on the Japanese market 

for 30 years, and its first-grade quality has taken 25% of the market share. Honshu Timely, Honshu 

Kinokurosu's associated company, is Japan's top supplier of wet hand towels and offers a wide range of 

products from the luxurious to the economical. The market for wet hand towels is considered to be 

growing steadily. However, the notion that wet hand towels are customarily given out free is quite strong 

among Japanese consumers, so common acceptance as a retail item may be slow. (1 fig) 

Author: Anon 

Source: Nonwovens Rev. 

Issue: Vol. 9, No. 4, Dec. 1998, p. 14 (In Japanese) 

Uni Charm - Top share holder in cosmetic cut cotton and baby wipe fields 

Uni Charm (UC) supplies a wide range of wipes and hand towels, and leads in the field of cosmetic cut 

cotton and baby wipes in Japan. Cosmetic cut cotton "Silcot" has been on the market for 24 years, and 

has become the top-rank brand, with a 30% market share. Recently the product has been improved to 

inner cotton sealed-in type which does not leave lint on the skin after use. This revision is expected to 

increase their market share by 20%. UC's baby wipes are competing well for top position with Pijon 

products, but the postponed launch of flushable baby wipes may be disadvantageous for UC. In 1997, 

UC launched wet tissues for pet dogs. These are made of a thick nonwoven impregnated with 

deodorizing and anti-bacterial substances. (5 fig) 

Author: Anon 


Issue: vol. 9, no. 4, Dec. 1998, pp 18-19 (In Japanese) 

High-strength polypropylene fibre 

Despite excellent processability, chemical-resistance and lightness, polypropylene fibre has poor fibre 

strength compared to other general resin fibres. Ube Nitto Kasei, Japan, has been working on this 

problem and has recently succeeded in manufacturing a high-strength polypropylene fibre. Ordinary 



isotactic polypropylene is used and melt spinning performed within normal spinning temperature range at 

speeds above several hundred m/min. Highly magnified roller drawing is possible under a temperature 

range higher than the crystallization dispersion temperature. Fibre strength greater than 10g/d can be 

achieved with a faster drawing speed than current types. Possible applications are ropes and nets 

requiring high strength and elasticity. Use for liquid filters for acid, alkali and paints is also appropriate 

due to excellent chemical-resistance. (2 fig, 3 tab) 

Author: Oota S 


Issue: vol. 9, no. 4, Dec. 1998, pp 38-39 (In Japanese) 

The development of spunbond biodegradable nonwoven 

Shinwa, Japan, has recently launched a spunbonded biodegradable nonwoven, which is made from 

polylactic acid resin, Lactron, developed by Kanebo Gosen. Confirmed as compatible with the human 

body, polylactic acid is very safe as a raw material. When disposed of it decomposes into carbonic acid 

gas and water by a microorganism action in the earth or sea. No hazardous gases are created when 

incinerated and required calories for combustion are only a third or half of polyethylene or 

polypropylene. A wide range of applications is anticipated, including sanitary and household items, and 

agricultural and construction materials. Shinwa’s development of biodegradable nonwovens has started 

with spunbond, but development for thermalbond and spunlace types are also underway. (1 tab) 

Author: Anon 

Source: Jpn Nonwovens Rep. 

Issue: no. 11, 10 Nov. 1998, pp 27-28 (In Japanese) 

Development of range of biodegradable materials 

Unichika, Japan, has recently developed “Terramac,” a range of biodegradable materials including 

sheets, films, fibres and spunbond. Unichika has worked on the development of naturally recyclable 

materials for about 10 years, and in collaboration with world-leading polylactic acid manufacturer, 

Cargill-Daw Polymers, they have transformed biodegradable raw material of polylactic acid into various 

product forms using original molding technology. A number of characters and potential properties of 

polylactic acid were drawn out during processing and added to each product of Terramac. Uses in 

agriculture, horticulture, construction, fishery, food sector and sanitary and household items are 

anticipated. Unichika plans for a 5,000t production scale in 3 years and 16,000t in 5 years for its 

Terramac products. 

Author: Anon 


Issue: no. 11, 10 Nov. 1998, p. 28 (In Japanese) 

Surface modification of aramid fibers to improve composite adhesion by plasma treatment 

P-aramid fibres are suitable as reinforcement fibres for high-performance composites because of their 

low density, increased elongation at rupture compared with steel wire, and high decomposition 

temperature. Their molecular structure governs their high chemical and mechanical resistance. Low 

fibre-matrix adhesion can be improved by treating the aramid fibres with plasma, which causes better 

moistening of the aramid fibres opposite to the epoxide matrix during composite manufacture. Etching 

and cleaning plasmas and plasma polymerization have been investigated. Optimum composite strength is 

achieved when all fibres are completely embedded in the matrix. (Short article) 

Author: Bechter D; St Berndt R; Oppermann W 

Source: Tech. Text. 



Issue: vol. 42, no. 1, Feb. 1999, p. E2 

Effect of loading rate on the mechanical behavior of fiber glass mat/epoxy composite 

Glass fibre mat/epoxy composites were tested to assess effect of loading rates on their performance. 

Loading rates were investigated in a range of 10, 50 and 250mm/min, and fracture behaviour of the 

laminated composites was determined using a fibre/matrix interface. Short beam bend and three point 

bend tests showed cracks occurring on the composite surfaces during loading, a process which would 

most likely be controlled by weak links such as poor fibre/matrix interfacial adhesion. Tensile strength of 

the composites decreased with increase of loading rate, probably due to voids in the matrix and at the 

interfaces. Interfacial shear strength did not display a significant loading rate dependence, while flexural 

strength was found to increase with loading rate. (4 tab) 

Author: Bayram A; Yaziki M; Korkmaz B 


Issue: vol. 42, no. 1, Feb. 1999, pp E3-E5 

Polyester staple fibre from Toyobo has high moisture absorption 

Osaka-based Toyobo Co Ltd has developed a polyester staple fibre that has a 10% rate of moisture 

absorption. This is compared to conventional polyester staple, which has a rate of absorption of only 

0.4%, climbing to about 1% with the application of special finishes. By using a chemical treatment, 

Toyobo has made its polyester even more absorbent than cotton. Further, cotton fibres tend to retain the 

moisture they absorb, but Toyobo’s polyester quickly releases it. The fibre’s hollow structure also retains 

warmth. Quilt fillings will be the principal application, (1 ref) (Short article) 

Author: Anon 


Issue: Apr. 1999, pp 6-7 

Tie-up for superabsorbent fibre products agreed by Kanebo Gohsen 

Kanebo Gohsen of Osaka will expand production of its highly water-absorbent fibre Bell Oasis. Japanese 

manufacturers Nippon Felt and Hattori Takeshi will develop industrial products, such as filters and 

medical items, and full-scale projects have already been initiated. Bell Oasis is a highly water- and 

moisture-absorbent fibre based on a proprietary acrylic polymer. It can absorb up to 80 times its own 

weight of water, and is heat resistant up to 150 deg C. (1 ref) (Short article) 

Author: Anon 


Issue: Apr. 1999, p. 7 

Injection molding of natural fibre-reinforced polypropylene 

Research into the use of natural fibres, as a replacement for glass fibres, in the reinforcement of injection 

molded polypropylene parts is described. Compromises need to be made on heat resistance but flax and 

low-THC hemp strains can offer price advantages over glass in the medium loading range. Fibre-matrix 

adhesion, compounding concerns such as hygroscopic properties, rheology, mechanical properties and 

special features are described. 

Author: Aurig T; Mennig G 

Source: Kunstst. Plast Eur. 

Issue: Kunstst. Plast. Eur. vol. 89, no. 3, Mar. 1999, pp 6-7, 30-32 

Low foaming spin finishes 



Low foaming is a new requirement for spin finishes, to aid processes such as hydroentanglement. The 

antistat component of the finish contributes highly to foaming but is a necessary ingredient, especially in 

high speed carding. Work has been directed at a target of no foam measurable after one minute, which is 

tested by means such as the perforated disc method. Hansa Textilchemie GmbH of Oyten, Germany uses 

a method where fibres are placed in a beaker and covered with distilled water, to determine the foaming 

qualities of the resulting liquor. Standardized tests are of further importance for products intended for 

hygiene and medical uses, to avoid skin irritation. 

Author: Niestegge R 


Issue: vol. 42, no. 2, Apr. 1999, pp E22-E23 

Outer textile linings for cars: an innovation 

The need to improve function, reduce costs and consider environmental implications is causing car 

manufacturers to change to new materials. Needle and pile floor carpets (NFC-PFC) fitted in the outer 

linings offer improvements in acoustic effect and lower weight, leading to reduced fuel consumption. 

Their porous structure minimizes noise from water on the road and reduces spray, while giving elastic 

protection against stone impact. They display positive characteristics in water absorption, drying 

behaviour, mechanical stability and strength, resistance to abrasion, tearing and weather, cleaning ability, 

assembly, endurance and recycling. The characteristics of a wheel-case lining, which may be adapted for 

different car types, are analyzed according to DIN 61210. (2 tab) 

Author: Elsele D 



1,000 frames per second: revealing the secrets of meltblown nonwovens 

Meltblowing is a sophisticated process that produces microfibres of under 10 microns in diameter which 

are condensed into a nonwoven web. Research into establishing the process factors affecting quality and 

into controlling the process itself has resulted in the formation of blur-free, freeze-frame and slow motion 

film images during production. Acceleration, velocity, diameter, orientation and entanglement of fibres 

as a function of distance from the die orifice can now be measured by newly developed equipment. 

High-speed single exposures and multiple exposures are achievable with a high-speed LSI 1000 pulsed 

laser from Oxford Lasers. The processing variables identified so far are air pressure, die-to-collector 

distance between which significant acceleration and velocity changes take place, and collector surface 

speed. 

Author: Lennox-Kerr P 



Development of nonwovens 

Within the nonwoven industry in India great potential exists for Indian companies to expand their 

activities into new applications through more research and development, greater customer awareness and 

faster production. The nonwoven process and web formation are explained and properties listed which 

can be obtained with the use of binders. The thermal, spun and self-bonded processes are described and a 

comprehensive list of nonwoven end products supplied. Principal fibres are covered, and statistical 

background on market growth (1994-2000) globally and process technologies used (1993 estimate) is 

given. Nonwoven consumption is low in India through lack of good quality raw materials and a heavy 

import duty structure for binders, but there is considerable potential for further development of the 



industry. (2 tab, 6 ref) 

Author: Shiva Prakesh A V 

Source: Indian Text. J. 

Issue: vol. 109, no. 4, Jan. 1999, pp 26-27 

Compression porometry for nonwoven fibrous mats 

Compression porometry represents an advanced tool for the analysis of pore paths in the long, in-plane 

dimension of fibrous materials as a function of compression. The new technique is particularly useful in 

the study of the effect of the incremental flattening of a mat on the bubble point pressure and of the 

relative pore diameters at the bubble point for the cases of z-direction and x,y-direction. The technology 

allows small, controlled changes in the mechanical pressure on the sample to obtain high-resolution plots 

of data at intermediate levels of compression. Data obtained by use of this new technology can prove 

particularly relevant for products whose manufacture and development requires information regarding 

the wetting characteristics and movement of air or liquids in an enclosed matrix subjected to differing 

levels of compression. 

Author: Perna V F; Wagner K 

Source: Allg. Vliesstoff-Rep. 

Issue: vol. 27, no. 2, 1999, pp 27-28; 29-30 

R and D trends: 1997 science and technology spending, Y15,741,500m highest ever showing a 

steady increase in the past three years 

In Japan 1997 science and technology spending was highest ever at Y15,741,500m, a 4.4% (Y662,200m) 

increase on 1996. Industry was the most active area (Y10,658,400m, 6.1% increase), followed by 

universities (Y3,059,200m, 1.5% increase) and public institutes (Y2,023,900m, 0.8% increase). Research 

trends were application and product development orientated, with basic research being suppressed 

slightly (13.8% of total research, 0.3% negative growth). For the first time female researchers numbered 

over 10% of total researchers in 1997. The aims of the Technical Licensing Organization (TLO) are also 

discussed. 

Author: Anon 


Issue: no. 2, Feb. 1999, p. 27 (In Japanese) 

Product introduction: vinylon chopped fibre nonwoven, VM Melt, from Japan Vilene Co Ltd, a 

new material as an alternative to glass fibre fabric 

Japan Vilene Co Ltd and Dainippon Ink KK have developed VM Melt from vinylon chopped strand 

fibre. It has been used as an alternative to glass-based materials for the water tanks of the Takehara 

Power Station (Hiroshima, Japan) and owing to its superb performance including chemical resistance, 

water resistance and mechanical strength under 5,000V testing, together with its ability to be converted it 

is now also being used as a surface protection material for concrete. Unlike the glass-based product, this 

product does not generate harmful particles during construction. The target sales in the first year are 

Y100m, and Y600m in three years. The vinylon mat complex (patent pending), combining the surface 

material and VM Melt, is also available. (1 fig) 

Author: Anon 


Issue: no. 3, Mar. 1999, p. 20 (In Japanese) 

JNR prospects: amorphous carbon fibre nonwoven, dream for its development and 



commercialization 

Amorphous metal has now reached the commercial application stage after 20 years research and 

development. This metal is the essential element for the success of the electric vehicle (EV) and 

hybrid-car. Amorphous carbon nano-fibre was first reported in January 1999, by Kogyo Gijyutsuinn, and 

nonwoven development using this fibre is anticipated. Once this task is achieved, the application of 

amorphous carbon nano-fibre nonwoven to the EV will be welcomed by the car industry, since the 

weight reduction of the car battery, by replacing amorphous metal with a nonwoven, is significant, and 

this will contribute to improving the practicality of the EV. 

Author: Shimizu T 


Issue: no. 3, Mar. 1999, pp 24-25 (In Japanese) 

Special edition, liquid filter: current status and prospect of nonwoven filter for blood treatment 

The necessity of blood treatment filters for the removal of leukocytes is widely recognized to ensure safe 

blood transfusion: 95% of these filters are polyester nonwoven based products. In addition to the 

separation performance determined by fibre diameter, as a medical product these filters have to meet 

tight regulations. Blood for urgent surgical needs is mainly used untreated as a new closed type system, 

in which a filter is integrated in the bleeding bag, will circumvent this problem. Nonwoven filters for 

uses other than leukocyte removal from blood transfusion is currently limited: filters for bone marrow 

treatment and for in vitro blood circulation treatment are showing potential. (9 fig, 4 tab) 

Author: Kaneko M 


Issue: no. 4, Apr. 1999, pp 9-13 

R&D trends: The nonwovens industry and SBIR (the Small Business Innovation Research) 

support system, positive outcomes expected 

The SBIR (Small Business Innovation Research) support program was introduced in Japan in 1999 with 

a Y1,600m national budget. SBIR is attracting interest from small and middle sized companies. A 

questionnaire carried out by Nikkei Newspaper indicated that SBIR is a priority interest for 64% of those 

companies questioned. The program includes financial support for the research and development 

projects. It is recommended that to become truly high-tech, the nonwoven industry should utilize this 

system. 

Author: Anon 


Issue: no. 4, Apr. 1999, p. 17 (In Japanese) 






ASSOCIATION NEWS 

International Nonwovens Technical Conference 2000 Set For Texas 

The 2000 International Technical Nonwovens Conference will be co-sponsored by INDA and TAPPI and 

is scheduled for September 25-28, 2000 at the Hotel Inter-Continental, Dallas, TX. INTC 2000 is the 

technical forum designed to provide opportunities for industry leaders to review the latest research, 

product innovations and market applications for all nonwoven technologies. INDA is currently accepting 

abstracts related to the following topics chosen by the INTC Conference Committee: 

● Fibers 

● Properties & Performance 

● Process Technologies 

● Filtration 

● Mats 

● Binders & Adhesives 

● Absorbents 

● Barriers 

● Melt Extrusion 

● Hydroentangling 

● General 

By presenting a paper at the INTC Conference, speakers will reinforce their expertise within the 

nonwovens community; gain recognition among peers and with potential customers; enhance their 

reputation as a leader within the industry; provide their company with invaluable industry visibility; and 

their written paper will be distributed to all conference attendees in the INTC 2000 Book of Papers. For 

end-users of nonwoven products, this conference is a unique opportunity to tell suppliers their needs. 

To receive more information about presenting a paper at INTC 2000, please contact Deanna Lovell, 

Education Coordinator, INDA, Association of the Nonwoven Fabrics Industry, P.O. Box 1288, Cary, NC 

27512-1288; 919-233-1210, ext. 119; Fax 919-233-1282; dlovell@inda.org; www.inda.org. 

Needlepunch 2000 Call For Papers 

INDA will sponsor Needlepunch 2000 at the Hyatt Regency Downtown, Greenville, SC, from April 

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26-28, 2000. Needlepunch 2000 is the nonwovens forum designed to provide opportunities for industry 

leaders to review the latest research, product innovations and market applications for all needlepunch 

technologies. INDA is currently accepting abstracts for the following topics chosen by the Needlepunch 

Committee: 

● 

● 

● 

● 

● 

● 

Competitive Technologies 

End Users Forum 

Fibers 

Machinery & Needle Advances 

International Trade 

Production 

To receive more information about presenting a 

paper at Needlepunch 2000, please contact Deanna 

Lovell, Education Coordinator, INDA, Association 

of the Nonwoven Fabrics Industry, P.O. Box 1288, 

Cary, NC 27512-1288; 919-233-1210, ext. 119; Fax 

919-233-1282; dlovell@inda.org; www.inda.org. 

EDANA Names New Officers 

EDANA, the Brussels-based Europ-ean Disposables 

and Nonwovens Association, recently re-elected 

Rolf Altdorf, vice president and managing director, 

PGI Nonwovens Europe, The Netherlands, chairman 

of EDANA for another one-year term of office. 

Aldo Ghira, managing director of Tenotex S.p.A., 

Italy, was re-elected as treasurer. Also elected as 

vice-chairmen were Ingemar Bengtson, managing 

director, Trioplanex International, Sweden, and 

Krzysztof Malowaniec, R&D director, Personal 

Care Products, Paul Hartmann, Germany. 

Four new governors were elected to EDANA's 

16-persons Board 

● Gianluigi Fornoni, Fiberweb Neuberger 

S.p.A., Italy. 

● Anne Mykkänen, Mölnlycke Health Care AB, 

Sweden 

● Gerd Ries, Johnson & Johnson, Germany 

● Georg Werner, Stockhausen, Germany 

Pourdeyhimi Joins NCRC 

Behnam Pourdeyhimi has joined the Department 

of Textile & Apparel, Technology & Management 

in the College of Textiles at North Carolina State 

university and has been appointed Co-Director of 

the Nonwovens Cooperative Research Center 

(NCRC). Pourdeyhimi received his PhD from 

Leeds University in 1982. This was followed by a 

short stint as a post doc at NCSU and then at 

Cornell University. His distinguished academic 

career has taken him through the University of 

Maryland (Assistant/Associate Professor, 

1984-1995) and Georgia Tech (Professor, 

1995-1999). 

Pourdeyhimi has taught textile and fiber science, 

technology and engineering as well as well as the 

application of microscopy and image analysis to 

textiles and materials problems both at 

undergraduate and graduate levels. His research 

experience covers such areas as image and 

structural analysis of nonwoven fibrous webs, 

textile applications in sports, bioengineering and 

materials, instrumentation and test method 

development, among others. His contributions to 

fiber/textile science, engineering and technology 

and his contributions to the profession have been 

well recognized by the Textile Institute and the 

Fiber Society. He served as the Fiber Society 

Lecturer in 1993 and as the president of the Fiber 

Society in 1995. 

The other continuing members of the 16-member EDANA Board of Directors are: Heikki Bergholm, 

Lassila & Tikanoja, Finland; Hermann Eidel, Freudenberg, Germany; Patrick Jeambar, Ahlstrom Lystil 

SA, France; Franz Junkermann, Colbond Nonwovens, The Netherlands; Frantisek Klaska, Pegas AS, 

Czech Republic; Jorma Leskinen, UPM-Kymmene, Walkisoft, Finland; Luc Maes, Libeltex, Belgium; 



and Reiner Schoene, Procter & Gamble, Germany 

EDANA Plans 2000 

Nonwovens Symposium 

A call for original papers has been issued by EDANA, the European Disposables and Nonwovens 

Assoc-iation, for the EDANA 2000 International Nonwovens Symposium that will take place in Prague, 

the Czech Republic, on June 7-8, 2000. 

The symposium will feature new developments in the markets for nonwovens, especially hygiene, as 

well as the latest advances in technology, fibers and webs, treatment and bonding, and related issues. 

EDANA invites short abstracts of proposed papers from companies, research institutes, universities and 

individuals for consideration of inclusion in the symposium program. The deadline for such submissions 

is November 30, 1999. They should be submitted to EDANA, 157 avenue Eugène Plasky, Bte 4; 1030 

Brussels, Belgium; Tel.: 32+2/734-9310; Fax: 32+2/733-3518; edana@euronet.be. 

Jacobs Awarded TAPPI 

Nonwovens Division Scholarship 

Cari Jacobs has been awarded the 1999-2000 TAPPI Nonwovens Division scholarship. Jacobs is a 

student in chemical engineering at Oregon State University and is a member of the Oregon State 

University TAPPI Student Chapter. 

Jacobs plans to graduate in 2001. After graduation she would like the opportunity to work in the 

nonwovens industry, ideally taking advantage of her skill in chemistry. Jacobs is a member of TAPPI, 

the American Institute of Chemical Engineering, the Society of Women Engineers, Phi Theta Kappa 

Honors Society, and the National Honors Society. She received an Academic Achievement Award in 

1996, was on the National Dean's List Award for academic achievement (1995-1996), has been on the 

Honor Roll since 1992 in both high school and college, and was a recipient of the Who's Who Among 

American High School Students Award (1994-1995). 

TAPPI's Nonwovens Division promotes the objectives of the association with respect to materials, 

equipment and processes for the manufacture and use of nonwovens. 

PaperBase and TAPPI Deal 

An agreement between TAPPI and Paperbase International now allows TAPPI members to arrange 

special access to the Paperbase International extensive database, called "PaperBase." 

Paperbase International is a consortium of the four leading pulp and paper institutes in Europe - CTP 

(France), KCL (Finland), Pira International (UK) and STFI (Sweden). The consortium was organized 

with the aim of combining their various databases in order to provide their memberships with full 

coverage of the latest technical, research and business information for the pulp and paper industry. 

With this new agreement, TAPPI members can obtain subscription to this database at a 20% discount off 

the annual subscription via the Internet. In addition, TAPPI members can subscribe to the PaperBase 

CD-ROM with a networking license at the same price as the single-user license - a 30% savings. 

An introductory offer includes access to PaperBase on the Web free of charge for a limited time. For 

more information, visit http://www.paperbase.org or http://www.tappi.org. 



NONWOVENS 

CALENDAR 

September 1999 


Sept. 21-23. INDA-TEC '99 International Conference & Suppliers' Showcase '99. Renaissance 

Waverly Hotel, Atlanta, GA. Marilyn Bellinger, INDA, P.O. Box 1288, Cary, NC 27512-1288; 

919-233-1210; Fax: 919-233-1282; www.inda.org 

Sept. 21-23. SITEC '99 The 3rd Shanghai International Techtextile Exhibition & Conference. 

Shanghai, China. Ellen Dillard, Miller Freeman, 2000 Powers Ferry Center, Suite 450, Marietta, GA 

30067; 770-563-0129; Fax: 770-818-9092; edillard@mfi.com 

Sept. 21-23. SINCE '99/ENA '99 - Meeting The 21st Century Nonwovens Challenge. Shanghai, China. 

Ellen Dillard, Miller Freeman, 2000 Powers Ferry Center, Suite 450, Marietta, GA 30067; 

770-563-0129; Fax: 770-818-9092; edillard@mfi.com 

Sept. 24-28. IPF - International Plastics Fair '99. Makuhari Messe, Tokyo, Japan. IPF Show 

Management Office, Kasumigaseki Bldg., 3-2-5 Kasumigaseki, Chiyoda-Ku, Tokyo 100-6012, Japan; 

+81-3-3503-7320; Fax: +81-3-3503-7620. 

Sept. 27-29. TAPPI/China Paper Conference and Exhibit. China International Exhibition Center, 

Beijing, China. TAPPI, P.O. Box 105113, Atlanta, GA 30368-5113; 800-332-8686; 770-446-1400; Fax: 

404-446-6947 (U.S.) or 800-446-9431 (Canada) or 770-446-1400 (Outside U.S. & Canada). 

Sept. 27-29. TAPPI/CORR Tech Asia. China International Exhibition Center, Beijing, China. TAPPI, 

P.O. Box 105113, Atlanta, GA 30368-5113; 800-332-8686; 770-446-1400; Fax: 404-446-6947 (U.S.) or 

800-446-9431 (Canada) or 770-446-1400 (Outside U.S. & Canada). 

Sept. 27-29. "PPE Systems: Putting it All Together. Personal Protective Equipment Seminar." 

Wilmington, DE, USA. Sponsored by 3M and DuPont. 800-659-0151, ext. 275. 

Sept. 30-Oct. 2, 1999. Bobbin Americas. Georgia World Trade Congress Center, Atlanta, GA: Bobbin 

Group of Miller Freeman Inc., P. O. Box 279, Euless, TX 76039; 800/789-2223 or 817-255-8050. 

October 1999 

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Oct. 3-6. ASTM D-13 Committee Meeting. Fort Lauderdale, FL. Bode Buckley, ASTM, 100 Barr 

Harbor Drive, West Conshohocken, PA 19428-2959; 610-832-9740; Fax: 610-832-9555; 

bbuckley@astm.org 

Oct. 3-7. Interpas '99 Exhibition. National Exhibition Centre, Birmingham, England. Reed Exhibition 

Companies; 203-840-6227; Fax: 203-840-9227. 

Oct. 5-8. Composites 2000: An International Symposium on Composite Materials. Trabant University 

Center, University of Delaware (Newark Campus), Newark, DE, USA. For more information contact: 

Center for Composite Materials, 201 Composites Manufacturing Science Laboratory, University of 

Delaware, Newark, DE. 302-831-8149; Fax: 302-831-8525; info@ccm.udel.edu 

Oct. 6. Medal of Excellence in Composite Materials. Trabant University Center, University of Delaware 

(Newark Campus), Newark, DE. Center for Composite Materials, 201 Composites Manufacturing 

Science Laboratory, University of Delaware, Newark, DE. 302-831-8149; Fax: 302-831-8525; 

info@ccm.udel.edu 

Oct. 6-7. Short Course - Pile Fabrics. Madren Conference Center, Clemson University Campus, 

Clemson, SC, USA. Kay James, Clemson University, P. O. Box 912, Clemson, SC 29633-0912; 

864-656-2200; Fax: 864-656-3997; dregister@clemson.edu. 

Oct. 11-12. Filtration in Transportation - 2nd International Conference. Stuttgart, Germany. Filter 

Media Consulting, Inc., P.O. Box 2189, LaGrange, GA 30241; 706-882-3108; Fax: 706-882-3039 or 

Lutz Bergmann Consulting, Birkacher Str. 2, D-73760 Ostfildern, Germany; Fax: 011-49-711-456-7753. 

Oct. 11-13. PPE Systems: Putting it All Together. Personal Protective Equipment Seminar. Phoenix, 

AZ. Sponsored by 3M and DuPont. 800-659-0151, ext. 275. 

Oct. 12-15. American Association of Textile Chemists and Colorists, International Conference and 

Exhibition. Charlotte Convention Center, Charlotte, NC. AATCC, Research Triangle Park, NC: 

919-549-8141; Fax: 919-49-8933; www.aatcc.org 

Oct. 12-14. 27th EUCEPA Conference/52nd Annual ATIP Meeting and IP-Exhibition. Grenoble, 

France. ATIP, +33- (0)- 1-45-62-11-91; Fax: +33- (0) -1-45-63-53-09. 

Oct. 14. INDA New Course for Converters. Wyndham Plaza, Philadelphia, PA. INDA, Association of 

the Nonwoven Fabrics Industry, P.O. Box 1288, Cary, NC 27512-1288; Tel: 919-233-1210; Fax: 

919-233-1282: www.inda.org 

Oct. 14-16. Techtextil Asia. Osaka, Japan. Messe Frankfurt K.K., The 2nd Kiya Bldg. 3F, 4-3-2 

Iidabashi, Chiyoda-ku, Tokyo 102-0072 Japan; +81-3-5275-2851; Fax: +81-3-5275-2867. 

Oct. 19-21. Textile Supplies & Services Expo. Palmetto Expo Center, Greenville. Harry Buzzerd, 

Executive Vice President, ATMA, 703-538-1789; Fax: 703-241-5603 or Textile Supplies & Services 

Expo '99, P.O. Box 5823, Greenville, SC 29606-5823; 864-233-2562; Fax: 864-233-0619 

Oct. 19-21. EDANA Absorbent Hygiene Products Training Course. Brussels, Belgium. Philip Preest, 

EDANA, European Disposables & Nonwovens Association, 157 avenue Eugène Plasky, Bte 4, 1030 

Brussels, Belgium; Tel: 011+32+2/734-9310; Fax: +32-2/733-3518; . www.edana.org. 



Oct. 20-21. AFS Topical Conference & Expo - Air Filtration Conference. Hyatt Regency, Minneapolis, 

MN. Charlotte Stripling, American Filtration & Separations Society, P. O. Box 1530, Northport, AL 

35476; 205-333-6111; Fax: 205-333-6446; afs@dbtech.net; www.afsociety.org. 

Oct. 20-22. The Fiber Society, 1999 Annual Conference. Madren Center, Clemson, University, 

Clemson, SC. Bhuvenesh Goswami, Clemson University, School of Textiles, Fiber and Polymer Science, 

161 Sirrine Hall, Clemson, SC 29634-1307; 864-656-5957; Fax: 864-656-5983; gbhuven-@clemson.edu 

Oct. 25-28. Polyester '99 (PET '99) 4th Annual World Congress - The Global Polyester Chain. 

Zurich, Switzerland. Maack Business Services, CH-8804 Au/near Zurich, Switzerland. Tel: 

+41-1-7813040; Fax: +41-1-7811569; www.MBSpolymer.com 

Oct. 26-29. Fundamentals of Textiles. Madren Conference Center, Clemson University Campus, 

Clemson, SC. Kay James, Clemson University, P. O. Box 912, Clemson, SC 29633-0912; 864-656-2200; 

Fax: 864-656-3997; pdregister@clemson.edu 

Oct. 27-29. Polyethylene Tereptha-late Technology (PET). Atlanta, GA. Beth Nielsen-Smith, The 

University of Toledo at SeaGate Centre, University College, Division of Continuing Education, 401 

Jefferson Ave., Toledo, OH 43604-1005. 419-321-5139; bnielse@utnet.utoledo.edu; 

http://www.utoledo.edu/colleges/ucollege 

Oct. 27-30. Composites '99 Convention and Expo. McCormick Place East, Chicago, IL. Composites 

Fabricators Association; 703-525-0511; Fax: 703-525-0743. 

Oct. 28-30. IFAI Expo - Industrial Fabrics Association International. San Diego Convention Center, 

San Diego, CA. Susan Larson, IFAI, 1801 County Road B W, Roseville, MN 55113-4062; 

800-225-4324; Fax: 651-631-9334; www.ifai.com 

Oct. 28-30. Industrial Fabrics Association International Expo. San Diego, CA. Bob Smith, 

800-225-4324; Fax: 612/631-9334; www.ifai.com 

Oct. 31-Nov 4. INSIGHT '99. Sheraton San Diego Hotel and Marina, San Diego, CA. Marketing 

Technology Service, 4100 South 7th Street, Kalamazoo, MI. 616-375-1236; Fax: 616-375-6710 

November 1999 

Nov. 2-4. FILTRATION '99 International Conference and Exposition. Navy Pier, Chicago, IL. INDA, 

P.O. Box 1288, Cary, NC 27512-1288; 919-233-1210; Fax: 919-233-1282; www.inda.org 

Nov. 9. INDA Needlepunch Production Basics. Greenville, SC. INDA, P.O. Box 1288, Cary, NC 

27512-1288; 919-233-1210; Fax: 919-233-1282; www.inda.org 

Nov. 9-10. ASTM Courses - Weathering and Durability. West Conshohocken, PA. ASTM, Technical & 

Professional Training Department, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959; 

610-832-9686 or 610-832-9685; Fax: 610-832-9668; smurphy@astm.org; 

Nov. 9-11. TECHTEXTIL South America. Sao Paulo, Brazil. Messe Frankfurt, Ludwig-Erhard-Anlage 

1, D-60327 Frankfurt am Main; +49-69-7575-6415/6578/6406; Fax: +49-69-7575-6541; 

techtextil@messefrankfurt.com 



Nov. 10-12. TANDEC '99 - 9th Annual Nonwovens Conference. The University of Tennessee 

Conference Center, Knoxville, TN. TANDEC-Textiles and Nonwovens Development Center, College of 

Human Ecology, 1321 White Avenue, Knoxville, TN 37996-1950. 423-974-6298; Fax: 423-974-3580. 

Nov. 14-16. Private Label 20th Anniversary - Megashow. Rosemont Convention Center, Chicago, IL. 

Private Label Manufacturers Association, 369 Lexington Avenue, New York, NY 10017. 212-972-3131; 

Fax: 212-983-1382. 

Nov. 14-19. American Chemical Society - Eastern Analytical Symposium. Somerset, NJ. Eastern 

Analytical Symposium, P.O. Box 633, Montchanin, DE 19710; 302-738-6218; Fax: 302-738-5275; 

www.eas.org 

Nov. 16-18. Short Course - Advanced Fiber Science. Princeton, NJ. Nicole Pozsonyi, TRI/Princeton, 

601 Prospect Avenue, P.O. Box 625, Princeton, NJ 08540; 609-430-4806; Fax: 609-683-7149; 

www.triprinceton.org 

Nov. 18. INDA Needlepunch Production Basics. Worcester, MA. INDA, P.O. Box 1288, Cary, NC 

27512-1288; 919-233-1210; Fax: 919-233-1282; www.inda.org 

Nov. 23-25. EDANA Nonwovens Training Course. Brussels, Belgium. Philip Preest, EDANA, 157 

avenue Eugène Plasky, Bte 4, 1030 Brussels, Belgium; 011+32+2/734-9310; Fax: +32-2/733-3518; 

www.edana.org. 

Nov. 24-25. 26th Aachen Textile Conference. Aachen Textile Centre, Aachen, Germany. Brigitte 

Küppers; +49-241/44-69-129; Fax: +49-241/44-69-100; contact@dwi.rwth-aachen.de 

Nov. 30-Dec. 2. Nonwovens Russia Expo '99. St. Petersburg Sport & Concert Complex, St. Petersburg, 

Russia. Steven Douglas, Peter's Town Exhibitions, 10th Krasnoarmeiskaya 19, St. Petersburg, Russia, 

198103. Tel: +7 (812) 327-5553; +7 (812) 259-4535; www.peterstown.com 

January 2000 

Jan. 7-8. Cotton Textile Processing Conference - 2000 Beltwide Cotton Conferences. Marriott 

Rivercenter and San Antonio Convention Center, San Antonio, TX. Kearny Robert, Cotton Textile 

Processing Conference, SRRC, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124; 504-286-4562; 

Fax: 504-286-4419; krobert@nola.srrc.usda.gov. 

February 2000 

Feb. 27-29. Annual Meeting INDA - Association of the Nonwoven Fabrics Industry, Four Seasons 

Resort, Aviara, Carlsbad, CA. Peggy Blake, INDA, Association of the Nonwoven Fabrics Industry, P.O. 

Box 1288, Cary, NC 27512-1288; 919-233-1210; Fax: 919-233-1282; www.inda.org 

March 2000 

Mar. 7-10. AFS - Annual Technical Conference & Expo. Myrtle Beach, SC. Charlotte Stripling, AFS, 

P.O. Box 1530, Northport, AL 35476-6530. 205-333-6111; Fax: 205-333-6446. 

Mar. 23-25. Techtextil North America. Cobb Galleria Centre, Atlanta, GA. Michael Jänecke, Messe 

Frankfurt GmbH, TechtextilTeam, Ludwig-Erhard-Anlage 1, D-60327 Frankfurt am Main; 



+49-69-7575-6415/6578/6406; Fax: 

+49-69-7575-6541; techtextil@messefrankfurt.com 

or Daniel McKinnon, Messe Frankfurt, Inc., 1600 

Parkwood Circle, Suite 515, Atlanta, GA 30339; 

770-984-8016 ext. 21; 

daniel.mckinnon@usa.messefrankfurt.com 

April 2000 

Apr. 3-7. World Filtration Congress 8. The 

Brighton Centre, Brighton, England. The 

Secretariat, World Filtration Congress 8, 48 

Springfield Road, Horsham RH 12 2PD West 

Sussex, England. +44 (0) 1403-265005; Fax: +44 

(0) 1403-257594. 

filtech.exhibitions@btinterent.com; 

www.elsevier.nl/locate/wfc8 

May 2000 

May 17-19. ANEX 2000 Asia Nonwovens 

Exhibition and Conference. Intex Osaka, Osaka, 

Japan. E. J. Krause & Associates Inc., John 

Gallagher, 301-493-5500; Fax: 301-493-5705; 

gallagher@ejkrause.com 

May 24-26. CINTE Tech Textil. The China 

International Nonwovens, Techtextiles & 

Machinery Exhibition and Conference. China 

International Exhibition Centre, Beijing, China. 

Messe Frankfurt (HK) Ltd., 1808 China Resources 

Building, 26 Harbour Road, Wanchai, Hong Kong. 

Shirley Yan, 852-2238-9932; Janet Lai, 

852-2238-9930; Fax: 852-2511-3466; 

mfhkfair@netvigator.com; www.techtextil.de 

June 2000 

June 7-8. EDANA's 2000 International Nonwovens 

Symposium. Prague, the Czech Republic. EDANA, 

Philip Preest, Marketing Director; 157, avenue 

Eugene Plasky, Bte 4, 1040 Brussels, Belgium; 

011+32+2/734-9310; Fax: +32-2/733-3518; E-mail: 

edana@euronet.be 

July 2000 

July 25-26. AFS - Water & Waste Water 

INDA Expanding Publishing Efforts 

With the goal of greatly expanding its publishing 

efforts within the worldwide nonwovens industry, 

INDA, Association of the Nonwoven Fabrics 

Industry, has partnered with Jacor Publications, 

Inc., Midland Park, NJ, to develop and produce 

highly targeted print and electronic media 

projects. 

Jacor Publications is headed by Michael 

Jacobsen, former editor of Nonwovens Industry 

magazine and of the Executive Report of the 

Nonwovens Industry and currently production 

editor of the INDA International Nonwovens 

Journal. Jacobsen will serve as Director of 

Publications Development for INDA, with the 

responsibility of researching and implementing 

focused publications for both INDA members 

and non-members. 

"INDA has recognized the need to increase its 

publications profile to further its aim of 

becoming the global resource for 

nonwovens-related information," said INDA 

president Ted Wirtz in announcing the 

partnership. "Our members have been asking us 

to continue to provide them with information on 

all aspects of their businesses, and expanding our 

effort through our relationship with Jacor is a 

major step in this direction." 

Wirtz pointed to specific targeted segments 

within the nonwovens industry, such as filtration, 

needlepunching and market research, as areas 

with much potential for INDA publications. 

"We are not looking to compete with any existing 

magazines or newsletters in the nonwovens 

industry, which already do a fine job providing 

our industry with information," Wirtz added. "We 

are looking simply to increase the amount of 

information that is published for our members." 

Jacor Publications, a custom publishing and 

internet services company, was founded in 

January, 1998 by Michael Jacobsen, who has 



Conference. Anaheim, CA, USA. Charlotte 

Stripling, AFS, P.O. Box 1530, Northport, AL 

35476-6530. 205-333-6111; Fax: 205-333-6446. 

August 2000 

almost 20 years of experience in the publishing 

industry. In addition to serving as editor-in-chief 

of Nonwovens Industry from 1985 through 1991, 

Jacobsen spent seven years directing the editorial 

operations of the leading trade magazines in the 

sporting goods and golf industries. 

Aug. 20-24. 220th American Chemical Society 

National Meeting. Washington DC, USA. ACS 

Meetings, 1155 16th St. N.W. Washington, DC 20036; 202-872-4396; Fax: 202-872-6128; 

natlmtgs@acs.org 

September 2000 

Sept. 26-28. International Nonwovens Technical Conference 2000, Joint INDA and TAPPI 

Conference. Hotel Inter-Continental, Dallas, TX, USA. TAPPI, Charles Bohanan; 770-209-7276; 

cbohanan@tappi.org. 

Sept. 28-29. Ninth International Symposium on Flammability and Sensitivity of Materials in 

Oxygen-Enriched Atmospheres. Paris, France. Dorothy Savini, Symposia Operations, ASTM, 100 Barr 

Harbor Dr., West Conshohocken, PA 19428-2959; 610-832-9677. 

October 2000 

Oct. 15-28. American Association of Textile Chemists and Colorists, International Conference and 

Exhibition, Benton Convention center, Winston-Salem, NC, USA. AATCC, Research Triangle Park, 

NC,. 

USA; 919-549-8141; Fax: 919/549-8933. www.aatcc.org 

Oct. 18-20. Techtextil Asia. INTEX Osaka, Japan. Michael Jänecke/Mrs. Silke Sakouchy, Messe 

Frankfurt GmbH, TechtextilTeam, Ludwig-Erhard-Anlage 1, D-60327 Frankfurt am Main; Tel: 

+49-69-7575-6415/6578/6406; Fax: +49-69-7575-6541; techtextil@messefrankfurt.com 

Oct. 23-27. ATME-1 2000 American Textile Machinery Exhibition-International 2000. Palmetto Expo 

Center, Greenville, SC, USA. J. Robert Ellis, ATME, P.O. Box 5823, Greenville, SC 29606. 

864-233-2562; Fax: 864-233-0619; E-mail: atmei@textilehall.com 

Oct. 29 - Nov. 3, 2000. American Chemical Society - Eastern Analytical Symposium. Atlantic City, NJ, 

USA. For more information contact: Eastern Analytical Symposium, P.O. Box 633, Montchanin, DE 

19710-0633; Tel: 302/738-6218; Fax: 302/738-5275; Internet: http://www.eas.org 

November 2000 

Nov. 26 - Dec. 1, 2000. 10th International Wool Textile Research Conference. Aachen, Germany. For 

more information contact: Deutsches Wollforschungsinstitut, Veltmanplatz 8, D-52062 Aachen, 

Germany; Tel: ++49 (0) 241/44-69-129; Fax: ++49 (0)241/44-69-100; E-mail: 

contract@dwi.rwth-aachen.de. 

April 2001 



Apr. 1-5, 2001. 221th American Chemical Society National Meeting. Washington DC, USA. For more 

information contact: ACS Meetings, 1155 - 16th St. N.W. Washington, DC 20036-4899; Tel: 

202/872-4396; Fax: 202/872-6128; E-mail: natlmtgs@acs.org 

Apr. 23-27, 2001. ATME-1 2001 American Textile Machinery Exhibition. Palmetto Expo Center, 

Greenville, SC, USA. For more information contact: J. Robert Ellis, ATME, P.O. Box 5823, Greenville, 

SC 29606. Tel: 864/233-2562; Fax: 864/233-0619; E-mail: atmei@textilehall.com 


Sep. 21-23, 1999. SINCE '99/ENA '99. Hong Kong, China. For more information contact: Ellen Dillard, 

Miller Freeman Inc., 2000 Powers Ferry Center, Suite 450, Marietta, GA 30067, USA. Tel: 

770/563-0129; Fax: 770/818-9092; E-mail: edillard@mfi.com 

October 2001 

Oct. 8-13, 2001. OTEMAS. 7th Osaka International Textile Machinery Show. Intex Osaka, Japan. For 

more information contact: Naad International, Tel: +81-6-945-0004; Fax: +81-6-945-0006. 

Oct. 21-24, 2001. American Association of Textile Chemists and Colorists, International Conference 

and Exhibition, Palmetto Expo Center, Greenville, SC, USA. For more information contact: AATCC, 

Research Triangle Park, NC, USA; Tel: 919/549-8141; Fax: 919/549-8933. Internet: www.aatcc.org 


Sep. 29-Oct 2, 2002. American Association of Textile Chemists and Colorists, International 

Conference and Exhibition, Charlotte Convention Center, Charlotte, NC, USA. For more information 

contact: AATCC, Research Triangle Park, NC, USA; Tel: 919/549-8141; Fax: 919/549-8933. 

Internet:www.aatcc.org 

October 2003 


and Exhibition, Palmetto Expo Center, Greenville, SC, USA. For more information contact: AATCC, 

Research Triangle Park, NC, USA; Tel: 919/549-8141; Fax: 919/549-8933. Internet: www.aatcc.org 

October 2004 


and Exhibition, Benton Convention Center, Winston-Salem, NC, USA. For more information contact: 

AATCC, Research Triangle Park, NC, USA; Tel: 919/549-8141; Fax: 919/549-8933. Internet: 

www.aatcc.org 




INJ Air Filtration 


Air Filters For Ventilating Systems 

— Laboratory and In Situ Testing 

By Jan Gustavvson, Technical Director, Camfil ab 619 33 Trosa, Sweden 

Abstract 

Over the past few decades, many laboratory test methods have been developed to measure and characterize air 

filters using different synthetic dusts. Today, with concern about indoor air quality (IAQ) and air pollution on the 

rise, new standards are being developed to test the ability of air filters to remove particles in the laboratory as well 

as in situ. Still, laboratory tests that use coarse dusts can give very misleading results, and the rated efficiency for 

a filter can decrease dramatically in real-world applications. For better understanding and prevention of IAQ 

problems, test methods should be extended to include particle shape, type, and properties. 

History of air filter standards 

There are many test methods for measuring and characterizing air filters. In the past, different countries have 

tended to develop their own test methods using different measurement principles and synthetic test dusts. Today 

there is a tendency toward more international or worldwide standards. ASHRAE Standard 52-68 was adopted for 

use in the United States in 1968 for testing fine and coarse filters. In 1976 it was replaced by ANSI/ASHRAE 

52-76, and in 1992 it was replaced by ANSI/ASHRAE 52.1-92 [1] As the name implies, this latest standard was 

approved by the American National Standards Institute (ANSI) as an American national standard. 

Manufacturers and authorities in most countries have accepted the old ASHRAE 52-76 test method, which was 

also adopted as the Eurovent 4/5 standard, with minor modifications. Eurovent is the European association for 

manufacturers of air-handling equipment. This, in turn, served as a basis for some European national standards 

and the new European CEN norm EN 779, which came into force in 1993 [2]. CEN is the European committee 

for standardization. 

As a result of modern technology and modified requirements, Eurovent submitted a recommendation in 1992, for 

a new standard that measures the fractional efficiency of filters used in general ventilation, Eurovent 4/9 [3]. The 

old Eurovent 4/5 has been replaced by the new Eurovent 4/9 standard. CEN has also decided to develop a new 

test method based on a filter's fractional efficiency. This new standard will be based in principle on Eurovent 4/9 

and include a procedure for discharging filters. In the United States, ASHRAE has been thinking along the same 

lines as Eurovent and has proposed a new standard - ASHRAE STANDARD 52.2, [4] which was adopted in June 

1999. The old ASHRAE 52.1 standard [1] will continue to be used as a test method for low efficiency filters. 

Figure 1 graphs the history of U.S. and European standards for ventilating filters since 1950. 

The growing demand for better control particles and filter performance has led to the development of an in situ 

method of measuring the fractional efficiency of general ventilation filters, Eurovent 4/10-1996 [5]. Nevertheless, 

the need for new and improved measurement methods continues to increase with the heightened awareness of 

problems with indoor air quality. Simple particle counts and measures of filter efficiencies will not be adequate 

file:///D|/WWW/inda/subscrip/inj99_2/airfilt.html (1 of 8) [3/21/2002 5:11:51 PM]


for future needs. Test measurements will need to be 

extended to include analysis of the particles themselves, 

including shape, type, and risk factors. 

Laboratory Test Dust 

In both the old and new test methods, filters are loaded with 

ASHRAE synthetic dust. Unfortunately, the synthetic dust 

gives no indication of the filter's actual useful life. Tested 

filters can have completely different characteristics when 

performing under actual operating conditions. 

One advantage of the new test methods that measure a 

filter's fractional efficiency is that they can use the same 

instruments and techniques to study filter performance 

when loaded with other types of dust. Perhaps more 

importantly, these tests can be run in the laboratory or 

under actual operating conditions. 

It is fair to ask whether laboratory tests using synthetic dust 

are representative of operation under real-world conditions. 

For example, filters installed in urban environments are 

exposed to exhaust fumes and gases from combustion 

products, while filters in a rural environment are exposed 

more to dust from nature. 

Figure 1 

U.S AND EUROPEAN STANDARDS FOR 

VENTILATING FABRICS SINCE 1950 

Consider the results for two different types of EU7 (85% 

dust spot efficiency filters) tested with different test dusts. 

One filter is a conventional glass-fiber filter in which the 

collecting mechanism is based on diffusion and 

interception of fine fibers. The other filter consists of coarse synthetic fibers that are electrostatically charged. 

One of the test dusts is "Arizona road dust" (AC fine test dust), representing "natural" dust in a rural environment. 

The other test dust consists of diesel exhaust fumes, representing an urban environment. 

AC Fine test dust. 

Figure 2 shows the results for a test with road dust. The efficiency of dust captured on the glass-fiber filter 

increased as the dust load increased. In contrast, the efficiency of the electrostatically charged material was 

somewhat higher in the beginning but decreased as the captured dust neutralized the charged fibers. Figure 3 is a 

high-magnification photo of AC fine test dust. 

For dust containing fibers or coarse particles, such as the widely used ASHRAE test dust, the efficiency often 

increases as the dust load increases, since a dust cake forms on the filter. Once it is formed, the dust cake does the 

actual filtering. 



Figure 3 

Figure 2 

THE EFFECT OF TEST DUST AC FINE ON TWO 

FILTER MATERIALS: ONE WITH 

ELECTROSTATICALLY CHARGED MEDIA AND ONE 

WITH CONVENTIONAL GLASS-FIBER MEDIA 

10 000 MAGNIFICATION OF AC FINE TEST 

DUST 

Figure 4 

THE EFFECT OF DIESEL FUMES ON AN EU7 

GLASS FILTER MEDIA 

Figure 5 

THE EFFECT OF DIESEL FUMES ON 

ELECTROSTATICALLY CHARGED EU7 FILTER 

MATERIAL 

Diesel fumes 

In tests with diesel exhaust fumes, the results were markedly different. The efficiency of the glass-fiber EU7 filter 

remained constant when the filter was loaded with diesel exhaust fumes, as seen in Figure 4. In contrast, the 

efficiency of the electrostatically charged synthetic-fiber filter fell dramatically from 70% to 10% after being 

exposed to only a moderate load of diesel fumes as seen in Figure 5. The difference is due to the different 

filtering mechanisms for the two filters. The diffusion-and-interception collection mechanism for the glass-fiber 

filter remains active even when the filter is loaded with contaminants. In contrast, the electrostatic charge on the 

synthetic fibers of the EU7 filter disappears, and the filter takes on the same properties as a coarse filter. Figure 6 

is a high magnification photo of diesel fumes. 



Figure 6 

10 000 MAGNIFICATION OF EXHAUST FUMES IN 

A GRARAGE 

Figure 7 

MAGNIFICATION OF ASHRAE TEST DUST. THE 

PARTICLES ARE CLOGGED TOGETHER AND 

ARE MUCH BIGGER IN SIZE, COMPARED WITH 

ATMOSPHERIC DUST 

Lähtimäki [6,7] showed that cigarette smoke and diesel fumes can quickly neutralize the electret fibers in a filter. 

He also showed that, in certain environments with fibers or coarse dust, neutralization of charged fibers can be 

counteracted if the filter clogs. This can happen when such filters are tested with ASHRAE test dust, which 

contains coarse fibers and particles. The presence of these coarse fibers in the filter enhances its dust-holding 

capacity. So a filter with coarse, electrostatically charged fibers will obtain a relatively flat and good efficiency 

curve when tested with the ASHRAE test dust. Although the filter may score "high marks" in lab tests, these 

results may not apply under actual operating conditions with real-world dust particles. 

Table 1 

EUROVENT 4/9 TEST OF TWO FILTERS 

Glass Synthetic 

Filter area(m 2 ) 9.2 7.6 

Initial pressure drop (Pa) 81 86 

Initial Efficiency, 0.4µm (%) 65.1 59.7 

Average Efficiency(%) 86.3 88.7 

Dust holding capacity(g) 605 666 

ASHRAE test dust 

Most of the standards for air filters specify the use of ASHRAE 52.1 test dust, which is a mixture of fine dust, 

cotton liners, and carbon black. Figure 7 is a high magnification photo of ASHRAE test dust. This test dust has 

been in use 30 years, and many filters have been developed to meet the test standards rather than performance in 

real life. 

With the variety of commercially available materials in use today, it is relatively simple to make filters from 

different materials and obtain the same laboratory test results. Table 1 summarizes the results for a glass fiber 

filter and a synthetic fiber filter that were both tested according to Eurovent 4/9. 

To obtain approximately the same performances, the glass fiber filter was made with 9.3 m 2 filtering area, while 

the synthetic filter was made with a filtering area of only 7.6 m 2 . The pressure drops, the efficiencies, and the 

dust-holding capacities are very close to each other. Both filters are classified as EU 7 filters. Despite having 20% 

less filter area, the synthetic filter has about 10% more dust-loading capacity. It seems to be a very good filter. 

The efficiency for both filters-as measured by the Eurovent 4/9 test-are almost identical, as seen in Figure 8. 



The same filters were then installed in two parallel installations for about one year. Filtration efficiency in 

outdoor air was checked regularly during this period. As seen in Figure 9 the efficiency for the glass fiber filter 

remained constant and increased slightly, while the efficiency for the filter with synthetic fibers decrease from 

about 65% to 25% during the same period. 

The explanation for this is that the synthetic filter is 

made of electrostatically charged, rather coarse 

fibers. The coarse fibers give a higher dust-loading 

capacity, and the coarse ASHRAE test dust forms a 

dust cake that improves the filter's efficiency during 

laboratory tests. In the real world, atmospheric dust 

neutralizes the electrostatic charge, and the efficiency 

decreases. Moreover, the small dust particles 

encountered in the world outside the laboratory do 

not form a filtration-enhancing dust cake. 

Actual Operating Conditions 

The prime task of an air filter is to remove impurities 

from the ambient air. It is therefore important to 

study how filtration efficiency changes under 

real-world operating conditions. When a filter 

collects dust, the pressure drop normally rises, and 

the dust functions as a filter material and improves 

the collecting efficiency. As a rule, the efficiency of a 

conventional filter that removes particles through 

diffusion and interception is greatest when it is time 

to replace the filter. However, in coarse filters, or 

filters in the lower range, particles accumulating in 

the filter can loosen and travel with the air flow 

through the filter when the pressure drop increases. 

Synthetic filters operating with electrostatically 

charged fibers perform differently: 

Figure 8 

EFFICIENCY VS. DUST FED ACCORDING TO 

EUROVENT 4/9 FOR TWO DIFFERENT EU7 FILTERS 

Figure 9 

LIFE TIME TEST OF TWO EU7 FILTERS 

• Fine fibers: When fine fibers receive an extra electrostatic charge, the fibers lose this charge fairly swiftly. 

Efficiency declines immediately in the beginning but then remains constant for a long period of time during the 

filter's operation, increasing towards the end when the pressure drop rises and the filter accumulates dust. 

• Coarse fibers: The collecting efficiency of coarse, electrostatically charged, synthetic filters often decreases 

sharply, on a continuous basis, during the greater part of the filter's operating life. The collecting efficiency often 

remains low during the entire useful life of the filter. 

The result varies with the type of dust and different operating conditions. The advantage of the new Eurovent 

4/10 method is that we now have an instrument to measure what happens during operation under real-world 

operating conditions. 



Figure 10 

LONG-TERM TEST OF AN EU7 GLASS-FIBER 

FILTER AND 

AN EU8 SYNTHETIC FILTER. (The test was 

conducted in a rural environment where the 

concentration of atmospheric impurities was low. 

The cycle goes much faster in an urban 

environment.) 

Figure 11 

LIFETIME TEST MADE AT SINTEF, NORWAY, 

COMPARING DIFFERENT FILTER 

QUALITIES.(1995). 

(The drop of efficiency goes very fast for 

electrostatically charged filter material) 

Air ventilating system 

Figure 10 shows how filter efficiency changes in relation to the operating time of a ventilation system. When 

new, the synthetic-fiber EU 8 filter has a relatively high efficiency, about 70% for 0.4 µm particles. As the filter 

loses its electrical charge, its ability to remove particles deteriorates sharply as its efficiency decreases to about 

20%, which is normal for this material when it is not electrostatically charged. In contrast, the efficiency of the 

glass-fiber EU7 filter remains relatively constant. Note that the test was conducted in a rural environment, where 

the concentration of atmospheric impurities was low. The cycle goes much faster in an urban environment. 

Lifetime tests 

Sintef (Trondheim, Norway) made a lifetime test of five different EU 7 filters [8]. Three glass-fiber filters and 

two synthetic filters from different filter manufactures were compared. Two filters of each type were purchased 

on the open market. These 10 filters were tested in parallel for more than one year. 

The results in Figure 11 show that the glass fiber filters had a small increase in efficiency during the test. One 

synthetic filter with electrostatically charged filter material suffered a steep decline in efficiency for 0.4µm 

particles — from 80% to 20%--within a couple of weeks. The other synthetic filter had a very low efficiency 

during the entire test period even though the pressure drop increased almost up to 400 Pa. The increase in 

pressure drop for the other filters was low, about 20 %. 

Neutralization 

In most applications, electrostatically charged filters will be neutralized and lose efficiency. An effective way to 

verify the loss of efficiency with the loss of the electrostatic effect is to compare charged and uncharged material. 

This can be done using ions, X-rays or dust loading, but the easiest way is to dip the material in isopropanol and 

then dry and retest it. This will give a good indication of what happens in an installation with atmospheric dust. 

Figure 12 shows the results for charged EU7 filters before and after neutralization with isopropanol. Clearly, the 

effects of neutralization can vary considerably. The worst-performing filter shows a drop from 77 to 8% of 0.4µm 

particles, while the drop for the best-performing filter is from 88 to 48%. These figures have been confirmed by 

comparing the filters' actual behavior in real conditions. Performance depends on the fiber size, the composition 

of the material, and the type of dust. The rate of decrease depends on the type and concentration of dust. 



The Nord test method UUS117 [9] will test electret 

filter material using isopropanol or diesel fume. 

The purpose will be to (a) determine whether the 

filter material is dependent on the electrostatic 

removal mechanism and (b) provide quantitative 

information about the importance of the 

electrostatic removal mechanism. 

Figure 12 

EXAMPLE OF THE EFFECT WHEN 

CHARGED EU7 FILTER MATERIALS 

ARE NEUTRALIZED WITH ISOPROPANOL 

Future 

Interest in air quality is expanding from the general 

environment to include indoor air quality, spurred 

in part by awareness of "sick building syndrome." 

This highlights the need for new and improved 

methods for testing air filters. Particle counts and 

filter efficiencies will remain essential variables, 

but analysis should also be extended to consider 

the nature of the particles themselves, including 

shape, type, and risk factors. 

References 

1. ANSI/ASHRAE Standard 52.1-1992. 

"Gravimetric and Dust Spot Procedures for Testing 

Air Cleaning Devices Used in General Ventilation 

for Removing Particulate Matter," American 

National Standards Institute, New York, 1992. 

2. CEN EN 779, "Specifications for Particulate Air 

Filters for General Ventilation," European 

Committee for Standardization (CEN), Brussels, 

Belgium, 1993. 

3. Eurovent 4/9-1992, "Method of Testing Air Filters Used in General Ventilation for Determination of Fractional 

Efficiency." Eurovent, Paris, revised 1996. 

4. ASHRAE Standard 52.2 "Method of Testing General Ventilation Air-Cleaning devices for Removal Efficiency 

by Particle Size." American Society of Heating, Refrigerating and Air-conditioning Engineers, Atlanta, June, 

1999 

5. Eurovent 4/10-1996. "Recommendation for in situ Determination of Fractional Efficiency of General 

Ventilation Filters," Eurovent, Paris, 1996. 

6. Lähtimäki, M. "Reliability of Electret Filters," Indoor Air 93 Conference Proceedings, Helsinki University of 

Technology, Finland, 1993, Vol. 6, p. 463. 

7. Lähtimäki, M. "Development of Test Methods for Electret Filters." Report 320, Nordtest, Espoo, Finland, 

1996. 

8. STF 11 A95052, "Long-term Tests of Filters in Real Environment," SINTEF, Trondheim, Norway, 1995. 

9. Nordtest Method Nt VVS 117, "Electret Filters: Determination of the Electrostatic enhancement Factor of 

Filter Media," Nordtest, Espoo, Finland, 1998. — INJ 




Eval of Filtration Performance 


Evaluation of the Filtration 

Performance of Biocide Loaded Filter Media 

By Wayne T. Davis, B. Alan Phillips, Department of Civil and Environmental Engineering, The University of Tennessee, 

Knoxville, TN 37996; Maureen Dever, Center for Materials Processing, The University of Tennessee; Thomas C. Montie and 

Kimberly Kelly-Wintenberg, Department of Microbiology, The University of Tennessee; and Sarah Macnaughton, Microbial 

Insights, Inc., Rockford, TN 

Abstract 

This paper presents the results of a study designed to evaluate the filtration performance of nonwoven filtration media which 

have been loaded with a variety of biocides for use as potential indoor air filters. A test stand was constructed based on a 

modification of the ASTM 1215 Standard to provide testing of the bacterial removal efficiency of the filtration media. 

Biocide-loaded filtration media were first tested on an ASTM 1215 test stand using standard monodispersed latex spheres to 

determine the particle removal efficiency as a function of particle sizes in the 0.5 to 2.0 micrometer sizes. A multichannel 

optical particle counter was used to assess the efficiency. Additional samples of the same media were then tested in the 

modified ASTM 1215 test stand, referred to as the Biocontaminant Indoor Air Quality Test Stand (BIAQTS) by atomizing 

bacteria (Gram positive and Gram negative) and fungi into the test stand. Initial bacterial testing was conducted using 

single-stage microbial samplers to determine the efficiency of filters for removing Escherichia coli (E. coli) bacteria and other 

bacteria. In addition to testing the filtration efficiency, additional tests were conducted on samples of the filter by placing small 

disk samples of the unexposed biocide-loaded filters and a non-loaded control filter onto microorganism-loaded agar in petri 

dishes. Microorganisms studied included four bacteria, a fungus, and an opportunistic pathogen. The samples were then 

incubated and quantitative analyses were conducted to determine the zone of inhibited growth of the microorganisms around the 

disks due to the biocide treatments which were applied to the filters. 

The results are presented for two of a series of biocide-loaded nonwoven filters which were prepared using two different 

techniques for loading the biocides: 1) nonwoven filters which were prepared by mixing the biocide with the polypropylene 

polymer prior to meltblowing the polymer into a filter - referred to as impregnated biocide, and 2) spray application of the 

biocides as a finish onto the filter media--referred to as post treatment. The effects of impregnated versus post treatment 

applications on filtration efficiency and on the inhibition of bacterial growth on the filters are presented. 

Introduction 

A number of studies have been conducted in which concentrations of bacteria have been measured in both ambient (outside) air 

and in the indoor environment. Meyer (1983) provided a summary of research efforts involved in measuring the concentration 

of bacteria. In 1899 measurements in Paris showed concentrations of 200 microbes/m 3 in the winter and nearly 12,000/m 3 in the 

summer. Lighthart and Shaffer reported in 1995 that concentrations of airborne bacteria had a maximum concentration of 1,368 

colony forming units (CFU) per m 3 with a 24 hour mean of 121 CFU/m 3 when measured above a grass seed field in Oregon. 

Walsh et al. (1984) reported that a concentration of 4000 CFU/m 3 was found in an outdoor environment. Walsh further reported 

that concentrations were found to be 7.6 to 14.25 times greater in the indoor environment than in the outdoor environment. 

Reports of bacteria concentrations as high as 10 5 to 10 6 have been observed in factories involved with the processing of cotton, 

and in factories processing vegetables and mushrooms. Based on the above broad ranges, it is reasonable to expect that values 

of at least 300-500 CFU/m 3 should be present at the very minimum in a typical indoor environment, with concentrations 

reaching much higher values at times. 

Heating, ventilation and air conditioning (HVAC) filters can be used to reduce the concentration of particles in the indoor air 

environment. These are particularly effective when there is a relatively large recirculation rate within the indoor volume such 

file:///D|/WWW/inda/subscrip/inj99_2/dever.html (1 of 8) [3/21/2002 5:07:25 PM]


that the air makes multiple passes through the filters (Wadden and Sheff, 1983). In a series of tests on 10 different commercially 

available indoor air filters, Davis et al. (1994) showed that filter efficiencies ranged from 2 to 30% on 0.6 mm particles up to 35 

to 90% on 4 mm particles, dependent on the filter and the air velocity through the filters. While the filters can effectively 

remove a significant portion of the particles in the air, including bacteria and other organisms, the filters can also provide sites 

for growth of microorganisms, particularly in humid air streams. 

The objectives of this study were to evaluate the effectiveness of biocide-loaded filters in 1) removing bacteria from the air 

stream, 2) preventing the growth of bacteria which were collected on the surfaces of the filter, and 3) to determine if the filters 

actually affected the potential growth of bacteria which passed through the media uncollected. To accomplish these objectives, 

filters were manufactured which 1) contained selected biocides within the polypropylene mix which was used to manufacture 

the fibers, referred to as impregnated biocide, and 2) in which the biocide was applied as a topical coating onto the fibers of the 

filter. 

Description of Test Stands 

The filters developed in this study were tested on two different filtration efficiency test stands. The first test stand was an 

ASTM 1215 test stand housed in the Indoor Air Quality Laboratory housed in the Department of Civil and Environmental 

Engineering at the University of Tennessee and constructed by the authors. The test stand allows for the evaluation of the 

filtration efficiency of flat filter media at velocities of 1 to 300 cm/s for monodispersed polystyrene latex (PSL) spheres with 

particle sizes of 0.5 to 3 µm. The ASTM 1215 Method and test stand are described in detail by ASTM 1215 (1989), and Davis 

(1994). The test stand was similar to that shown in Figure 1, except that it was only used for testing of PSL spheres and di-octyl 

phthalate (DOP). 

Figure 1 

BIOCONTAMINANT INDOOR AIR QUALITY (BIAQ) TEST CHAMBER 

The second test stand, referred to as a 

Biocontaminant Indoor Air Quality Test Stand 

(BIAQTS) was designed and constructed by the 

authors and installed at Microbial Insights, Inc. 

The test stand, shown schematically in Figure 1, 

provides the ability to expose a filter to a 

constant air flowrate (and filtration velocity) 

which contains a constant concentration of a 

biocontaminant (bacteria or fungal spores), and 

to test the efficiency of the filter for removal of 

the biocontaminant by isokinetically sampling 

upstream and downstream of the media. Air is 

pulled into the test stand from the laboratory 

through two 99.9% HEPA filters in series to 

provide an air stream with a near zero particle 

concentration. A TSI Model 3076 Constant 

Output atomizer is used to atomize water 

droplets containing a relatively constant 

concentration of bacteria, fungal spores, or PSL 

latex spheres. The droplets are then dried in the 

upper portion of the vertical test stand as they 

mix with the larger volume of drier air from the HEPA filters. The air flow containing the concentration of biocontaminant then 

passes down through the test stand, through the filter, and out through a final HEPA filter and regenerative pump and is vented 

into a laboratory exhaust hood. The vertical filter holder is enclosed in a cabinet which is equipped with a glove box entry as an 

additional precaution. 

The test stand is equipped with three different techniques for quantifying the upstream and downstream concentrations of 

particulate contaminants. Two sets of upstream/downstream sampling probes are positioned in the test stand to allow isokinetic 

sampling of the air flow. One set of probes can be used to isokinetically sample into an optical particle counter for sampling of 

PSL latex spheres or DOP in cases where no bacteria are present. It was not possible to sample bacterial concentrations with the 

OPC for several reasons. First, the OPC cannot distinguish between viable and non-viable bacteria. Second, a 0.1 molar 

phosphate buffer solution was required to achieve a sustained bacterial survival over the course of the inoculation period for the 

bacteria. The buffer solution containing the bacteria was then atomized to create a relatively stable, viable concentration of 

bacteria in the air stream. Unfortunately, the presence of the buffer produced very high concentration of particles which were 

not bacteria to which the OPC responded. The concentration of bacteria was in the range of 100 CFU per cubic foot of air flow, 



whereas buffer itself created several orders of magnitude higher concentrations of particles of a non-bacterial origin. 

The second set of probes was used to simultaneously sample isokinetically into two Andersen single stage microbial samplers 

or into two all-glass liquid impingers (AGLIs) in order to evaluate the bacterial removal efficiency of the filters. Isokinetic 

sampling at a constant flow rate is important for accurate and quantitative data collection from the BIAQTS airstream. The 

sampling probes used to extract samples from the BIAQTS into the Andersen and AGLI samplers were sized to provide one 

cubic foot per minute (1 CFM) isokinetic samples from the test stand when the stand was operated at 15 CFM. The BIAQTS 

was calibrated using the upstream Anderson microbial air sampler to capture and quantify viable bacteria introduced into the 

system. Using live biomass (Escherichia coli; ATCC strain #8739) aerosolized and introduced into the BIAQTS at a flow rate 

of 15 CFM, samples were collected using the microbial samplers for various time periods ranging from 6 seconds to 10 minutes 

to ensure that the viable counts collected in the microbial samplers increased linearly with increasing sampling time. 

Bacteria are extracted from the test stand into the sampling probe, pass 

into the microbial sampler through a plate with a uniform array of holes 

and then impact into a petri dish as the air flow direction changes. 

Bacteria passing through each hole in the plate impact directly into the 

petri dish. Viable colony forming unit (CFU) counts were linearly 

correlated with increased sampling time (r 2 = 0.99; Figure 2), indicating 

that the BIAQTS was running at a constant rate and that the response of 

the sampler was linear within the sampling times that were to be used. 

Certain overall project objectives required the need to collect 

substantially greater numbers of bacteria than could reliably be measured 

with the Anderson microbial samplers due to the finite number of holes 

in the impactor plate. For example, it was necessary to sample using the 

AGLI samplers to acquire sufficient numbers of bacteria to be used to 

conduct signature lipid biomarker (SLB) analyses on the bacteria. The 

Figure 2 

CORRELATION BETWEEN TIME (MIN) 

AND COLONY FORMING UNITS (CFU) 

biomass density per unit volume required for the lipid biomarker analysis at 10 6 total organisms was significantly higher than 

the upper limit which could be measured with the Andersen air sampler at 10 3 total organisms. The AGLI samplers were 

actually calibrated for this purpose by placing the Andersen samplers upstream and downstream of the AGLI and evaluating its 

collection efficiency at the 1 CFM flowrate. The efficiency of the AGLI sampler was determined to be 79 ± 7%. The AGLI 

samplers are used to quantify bacterial numbers when there is a need to sample high concentrations (>10 4 ) of bacteria such as 

for lipid biomarker analysis. 

Description of Indoor Air Filters 

Nonwoven polypropylene filters containing known biocides were generated at the University of Tennessee (UT) Textiles and 

Nonwovens Development Center (TANDEC). Of the biocides chosen for testing, only one was a solid powder and compatible 

for combination with the polypropylene prior to the melt-blown process by which the filters were produced. All other biocides 

(liquids or suspensions) were topically applied to the filters using a spray chamber. The presence of topically applied biocides 

was confirmed by zone of inhibition testing on a bacterial lawn. The presence of the powder-based biocide was confirmed using 

a scanning electron microscope equipped with an energy-dispersive x-ray spectrometer (SEM-EDX). In the SEM mode with a 

high depth of resolution, it is possible to see the individual fibers of the air filter 

(Figure 3). Use of the EDX in combination with the SEM provided a 

quantitative determination of the presence of elements with atomic 

numbers six and greater. Photographs from the SEM of filters 

containing the polymer-based biocide showed fibers with "light specks" 

on the surface and analysis by EDX has shown these to be the biocide. 

Analysis by EDX also showed that the trend in the amount of 

polymer-based biocide present within the filters did not correlate well 

with the relative concentration of biocide which had been added to the 

polypropylene prior to filter production. This indicated that there was 

some nonuniformity in the ability to mix the biocide with the 

polypropylene prior to being meltblown. 

The meltblown polypropylene filters used in this study had a 

permeability of approximately 300 to 450 CFM/ft 2 at 1.3 cm( 0.5") 

H 2 O. The BIAQTS and the ASTM 1215 test stands were operated at 15 



CFM and the diameters of the filter holders in each system were 10.2 

cm (4 inches). At 15 CFM, the filtration velocity through the filters was 

172 fpm (87 cm/s). At this condition, the control filters had a pressure 

drop of 0.19-0.28 inches of H 2 O. The effective fiber diameters of the 

control filters were approximately 7 to 8 micrometers in diameter. The 

pressure drop of the polymer-based biocide-loaded filters and the 

effective fiber diameters were the same as for the control filters, since 

this biocide was added to the polypropylene and did not alter the fiber 

structure. However, significant changes occurred in the filters which 

were treated with the topically applied biocides. The filters with 

topically applied biocides had pressure drops ranging from 2.2 to 4.2 

inches of H 2 O and effective fiber diameters of 9 to 15 micrometers. 

Additional study is needed to determine a more effective means of 

applying the biocides without significantly affecting the filters' flow 

characteristics. 

Results: Filtration Efficiency 

The first series of tests involved an evaluation of the effect of seven 

different biocides on the removal efficiency of the filters. Tests were 

conducted in the ASTM 1215 test stand to determine the efficiency of 

the control filter, the polymer-based biocide-loaded filters, and six 

topically applied biocides on 1 µm PSL spheres. All tests were 

conducted at a velocity of 172 fpm (15 CFM through the 10.2 cm (4 

inch) diameter filters). The results are summarized in Table 1. As 

shown in the table, the efficiency of the control filters on 1 mm PSL 

spheres was 97.7%. The efficiency of the polymer-based 

biocide-loaded filters ranged from 94.3-96.5% for the 1 µm PSL 

spheres, indicating that the effect of the biocide on the efficiency was 

Figure 3 

PHOTOMICROGRAPHS OF THE CONTROL (TOP) 

AND BIOCIDE (BOTTOM) FILTER 

relatively small. This was expected since the pressure drop of the biocide impregnated filters had not changed significantly. The 

topically-applied biocide-loaded filters had efficiencies varying from 98.6-99.57% suggesting that the efficiencies had increased 

slightly. This was probably a result of the higher pressure drops of these filters after the biocides were topically applied 

resulting from a blockage of pores within the filters. 

Table 1 

SUMMARY OF FILTRATION EFFICIENCY RESULTS 

Fiber Diam 1 µm PSL Bacterial 

Biocide Counts (µm) P (cm/in.H 2 O) Efficiency,% Efficiency, % 

Control 0 7.8 0.71/0.28 97.7 95.4 

Polymer-based 697 7.6 0.71/0.28 96.4 99.66 

Polymer-based 1,333 7.7 0.56/0.22 95.8 99.60 

Polymer-based 1,578 8.0 .71/0.28 96.0 99.87 

Polymer-based 2,252 8.5 .48/0.19 95.8 99.5% 

Polymer-based 2,255 8.3 0.71/0.28 96.5 99.50 

Polymer-based 3,932 8.6 0.71/0.28 94.3 99.41 

D NA 15.4 10.7/4.2 98.5 99.93 

H NA 11.2 7.6/3.0 98.9 99.61 

K NA 11.0 5.6/2.2 97.4 99.99 

L NA 14.9 6.9/2.7 97.2 99.98 

M NA 13.2 7.4/2.9 98.7 99.86 

N NA 9.4 5.8/2.3 97.4 96.0 

O NA 13.2 7.6/3.0 97.7 99.79 



Figure 4 

PHOTOMICROGRAPHS OF THE CONTROL (TOP) 

AND BIOCIDE (BOTTOM) FILTER 

Additional samples of the same filters were then tested in the BIAQTS 

to determine the removal efficiency for E. coli. bacteria. E. coli. were 

chosen as test bacteria for their ease in preparation, as well as the fact 

that they are commonly occurring bacteria. The E. coli. are rod-shaped 

Gram-negative bacteria which have a diameter to length of 

approximately 1.1-1.5 µm to 2-6 µm. Tests on the BIAQTS were 

conducted at the same conditions of the ASTM 1215 tests and are also 

summarized in Table 1. Figure 4 shows a graph of the penetration of 

the E. coli., as measured by the Andersen microbial samplers upstream 

and downstream of the filter, versus the quantity of polymer-based 

biocide applied to the filter. The fractional penetration through the filter 

is equal determined from Table 1 as Penetration = (1-(Efficiency/100)), 

and represents the portion of the bacteria passing through the filter, 

where 1.0 represents 100% passage. The polymer counts (as measured 

by x-ray diffraction analysis--XRDA) is directly proportional to the 

polymer concentration in the filter. For approximation purposes, the 

counts ranged from 0-4000 counts, whereas the polymer-based biocide added to the polypropylene ranged from 0 to 1% by 

mass. The penetration of E. coli. for the control sample in the BIAQTS was approximately the same as that measured previously 

in the ASTM 1215 stand (0.046 versus 0.023); the efficiencies were 95.4 versus 97.7%. However, in all cases, the efficiencies 

of bacterial removal on the biocide loaded filters were substantially greater than the efficiencies of PSL sphere removal, as 

shown in Figure 4. Efficiencies ranged from 99.5 to 99.87% (penetrations of 0.005 to 0.0013). 

The actual cause of this increased efficiency is not completely understood at this time. It was initially proposed that it might be 

an electrostatic effect associated with the atomizer. To address this issue, tests were conducted on PSL spheres in the ASTM 

1215 test stand with and without a charge neutralizer at the test conditions above using the filters. No significant difference was 

observed, indicating that electrostatic charging of the atomized droplets is not the likely source of the change in efficiency. It 

was also suggested that the effect might be caused by the Gram-negative nature of the E. coli. However, if that were true, the 

control sample should have had the same efficiency as the polymer-based biocide-loaded filters. Based on tests to date, it is 

proposed that the biocide loaded filters not only remove bacteria, but that there is a strong indication that some portion of the 

bacteria passing through the filter may become sterilized, thus creating the higher effective collection efficiency of the 

biocide-loaded filters when compared to the control filter. Based on separate research being conducted by Phillips et al. (1995) 

on indoor air quality filters using PSL spheres and DOP at the same conditions of this study, it has been found that dried 

particles are substantially less efficient than DOP (oil droplets) of the same diameter, showing that particles at these high 

velocities representative of indoor air filters exhibit significant particle bouncing as they pass through filters. The dried bacteria 

present in the BIAQTS would exhibit a similar behavior, suggesting that they would have come in physical contact with 

multiple fibers as they passed through the filters. This contact may have enhanced the efficiency as measured by the microbial 

samplers, since the samplers only measure the viable bacteria. 

Later tests were also conducted downstream of a control filter and a polymer-based biocide-loaded filter by sampling into an 

AGLI sampler, after which an analysis was conducted to determine an approximation of the number ratio of total bacterial 

counts to viable counts. When direct counts (obtained using acridine orange direct counting (AODC)) were compared to viable 

plate counts (CFUs) following exposure to a polymer-based biocide-loaded filter, the ratio of direct counts to viable counts was 

far higher for the treated filter (956:1) than for the control (475:1). This is further evidence that bacterial death occurred after 

flow through the biocide-impregnated filters. Further testing is needed to confirm the source of the observed increases in 

efficiency. 

Efficiency tests were also conducted on six topically-applied biocides in the BIAQTS. These tests showed results which were 

similar to that of the impregnated filter discussed above, although tests were only conducted at a single loading. As shown in 

Table 1, the efficiencies of five of the topically-applied biocide-loaded filters ranged from 99.6 up to 99.99% and were 

substantially higher than the efficiency of the control filter (95.4%). In this case, however, some portion of this increase may 

have been attributable to the increased flow resistance and plugging of the filter pores, as indicated by the higher pressure drops 

of these filters. One of the biocides did not show any substantial increase in efficiency resulting from topical application of the 

biocide. 

Inhibition of Bacterial Growth 

To enable detection of biocidal activity on the filters, attempts were made to extract and culture bacteria from the filters after 

being left overnight on the filters (polymer-based biocide being a slow acting biocide). The filters were vortexed in 0.1 M 



phosphate buffer containing 0.05% Triton-X 100 (detergent), followed by plating the bacteria onto Nutrient® agar and 

incubated for 24 hours at 37 o C. While 5.14 x 10 4 CFUs were able to be extracted from the control filter, no CFUs were able to 

be extracted from any of the biocide-impregnated or topically-loaded filters, demonstrating efficient biocidal activity. There was 

some concern that this technique may not be an accurate measure of the inhibition of growth on the filter, since the extraction 

process would also expose the bacteria to biocide which may have been washed from the filter. 

In an effort to more fully understand the potential for inhibition of growth on the filters, tests were conducted in which the 

above biocides as well as additional biocides were sprayed onto samples of the polypropylene filter used in this study. After the 

filters were dried, small disks were punched from the control and biocide-loaded filters and placed upon tryptic soy agar plates 

which had been treated with either bacteria or fungi. Two different series of tests were conducted. In the first, 0.1 ml of cells 

were placed on the agar plates and spread with an "L" shaped rod upon the surface of the agar. In the second set of tests, cells 

were placed in the agar by mixing them into the agar prior to pouring the agar into the petri dishes (referred to as the pour-plate 

method). The use of the two different techniques was an effort to provide optimum growing conditions for cells that might 

prefer significant exposure to air as opposed to less exposure to air (the pour-plate method). After placing the filter disks upon 

the agar plates, the plates were incubated at either 25 o C or 37 o C for 24 to 36 hours. After incubation, zones of inhibition were 

determined by measuring the areas of no growth around the disks using calipers. All tests were conducted in duplicate, and a 

control disk (no biocide added) was included on each plate. 

The results of the inhibition tests are shown in Table 2 for a variety of bacteria: 

Escherichia coli - Gram-negative, rod shaped bacteria 

Staphylococcus aureus - Gram-positive, sphere shaped 

Streptococcus pyogenes - Gram-positive, strep throat bacteria 

Pseudomonas aeruginosa - Gram-negative, opportunistic, antibiotic resistant 

Saccharomyces cerevisiae - yeast, single cell fungal group 

Candida albicans - opportunistic pathogen 

Table 2 

ZONE INHIBITION RESULTS FOR VARIOUS BIOCIDES 

Candida 

albicans 

Escherichia Staphylococcus Streptococcus Pseudomona Saccharomyces 

Coli aureus pyogenes aeruginosa cerevisiae 

Biocide smear pour smear pour smear pour smear pour smear 

smear 

C + ++ ++ -- ++ ++ -- -- ++ 

++ 

D ++ +++ +++ +++ +++ ++++ +++ ++ ++++ 

+++ 

E ++ - ++ ++ +++ ++ + -- 

++ 

F ++ + ++ ++ +++ ++ + + + 

++ 

G ++ ++ ++ ++ ++ ++ -- ++ 

++ 

H -- -- -- -- -- -- -- -- -- 

-- 

I -- -- -- -- -- -- -- -- -- 

-- 

J -- -- -- -- -- -- -- -- -- 

-- 

K ++ ++ +++ ++ ++ +++ -- -- ++ 

-- 



L + -- ++++ + +++ + -- + +++ 

++++ 

M + -- + + + m -- -- + 

++ 

N +++ ++ ++ ++ ++ m -- -- -- 

-- 

O +++ ++ +++ ++ ++++ ++++ ++++ +++ ++++ 

++++ 

P -- + ++ ++ -- m -- + +++ 

++ 

Control -- -- -- -- -- -- -- -- -- 

-- 

-- no zone; + zone diameter of 8-15 mm; ++ zone diameter of 15-25 mm; +++ zone 

diameter of 25-40 mm; 

++++ zone diameter > 40 mm; m indicates missing data or inconclusive data. 

The control filters showed no zone of inhibited growth on any of the plates that were tested. The zone of inhibition for the 

various biocides ranged from no measurable zone of inhibition to greater than a 40 mm diameter zone of inhibited growth, 

depending on the biocide and the type of microorganism being tested. Biocides D and O showed superior inhibition to all 

microorganisms that were tested whereas Biocides H, I, and J were similar to the control samples with no zone of inhibited 

growth. There was some evidence that the zone of inhibition may have been related to the degree of solubility of the biocide in 

water. While this type of test would favor such biocides, it is also true that this type of biocide would probably perform better 

within a filter which was placed in a humid environment such as occurs in HVAC systems. So the test, although sensitive to the 

solubility of the biocide is probably a good indicator of the performance that might occur in filter applications. A final test was 

conducted on samples of each of the biocide-loaded filters listed in Table 2 to determine the effect, if any, of the degradation of 

the biocide when exposed to light for 14 hours. The results of these tests showed that there was no effect on any of the biocides 

due to exposure to light for the period tested. However, the long term stability of the biocides was not tested, and is an area for 

future study. Data collected in which the incubation period was held at 37 o C were not included in this paper since the results 

were very similar to those obtained with an incubation period of 250C. 

Conclusions 

A Biocontaminant Indoor Air Quality Test Stand was successfully designed and constructed which provided the ability to 

evaluate the removal efficiency of filters which had been loaded with biocides. An evaluation of the filters showed that effective 

biocides were identified which had the ability to effectively remove a variety of microorganisms, including bacteria and fungi. 

In all but one of the eight biocides which were tested for bacterial removal efficiency using E. coli, the removal efficiencies 

were found to be significantly greater than were achieved with the control which contained no biocide. In the case of the 

polymer-based biocide, there was some indication that the increased efficiency may have been due, in part, to bacteria which 

passed through the filter, but whose ability to form CFUs had been inhibited. In the case of the topically applied biocides, the 

enhancement in efficiency may have been due to the biocide being applied to the filters, increasing the pressure drop and 

blocking the pores. 

Fourteen of the biocides-loaded filters were evaluated to determine if the biocides created a zone of inhibited growth near the 

filters when exposed to a variety of microorganisms. Eleven of the biocides showed a zone of inhibition on at least some of the 

organisms. Two of the biocides showed significant zones of inhibition for all of the microorganisms tested. 

Acknowledgments 

The authors wish to express appreciation to a variety of sponsors who partially funded this work. The work was funded, in part, 

by the National Science Foundation (Grant NSF BES-9411572) which provided specific equipment used in the study, Olin 

Chemical Corporation who funded development of the filter media, TANDEC and Exxon Chemical Company (Baytown, TX) 

which provided meltblown filter production facilities, to NASA (Contract NAS9-19302) which provided funds for the bacterial 

filtration efficiency testing of the filters, and to the Center for Indoor Air Research (Contract 95-09) which provided funds to 

build the BIAQTS. It was only through the cooperative nature of these various sponsors that the multidisciplinary nature of this 

research could be accomplished. 

References 

ASTM F1215-89. Standard Test Method for Determining the Initial Efficiency of Flatsheet Filter medium in an Airflow Using 

Latex Spheres, American Society for Testing and Materials, Philadelphia, PA, 1989. 



Davis, W.T., C. Cornell, and M. Dever, "Theoretical Efficiencies of Residential Air Filters," TAPPI Journal, Vol. 76, No. 7, 

1994. 

Davis, W.T., "Air Filtration Efficiency Testing," TAPPI Journal, Vol. 77, No. 2, pp. 221-226, Feb. 1994.. 

Phillips, B.A., W.T. Davis, and M. Dever, "Investigation of the Particle Collection Efficiency of Melt Blown Media at High Air 

Velocity," Proceedings of the American Filtration and Separations Society 1995 Technical Conference, Nashville, TN, April 

23-25, 1995. 

Lighthart, B., and B. T. Shaffer, "Airborne Bacteria in the Atmospheric Surface Layer: Temporal Distribution above a Grass 

Seed Field," Applied and Environmental Microbiology, Vol. 61, No. 4, pp. 1492-1496, 1995. 

Meyer, B., Indoor Air Quality, Addison-Wesley Publishing Company, Inc., Reading, MA, p. 107, 1983. 

Wadden, R.A., and P.A. Sheff, Indoor Air Pollution, John Wiley & Sons, Inc., 1983, p. 106. 

Walsh, P. J., C. S. Dudney, and E. D. Copenhaver, Indoor Air Quality, CRC Press, Inc., Boca Raton, FL, pp. 176-178, 1984. 



- INJ 


Melt Blown Web Properties 


Characterization of Melt Blown Web Properties Using Air Flow 

Technique 

By Peter Ping-yi Tsai, Textiles and Nonwovens Development Center (TANDEC), The University of Tennessee, Knoxville, TN 

Abstract 

Fiber size, pore size, and air permeability are three important properties in melt blown (MB) webs. Air permeability governs the air 

resistance or the pressure drop of the air through the web. One of the major applications of MB webs is for air filters. Fiber size 

dominates the web air filtration efficiency. Liquid filtration is another major application of MB webs. Pore size of the web 

determines the rated particle size in liquid filtration. Air permeability can be easily determined by air permeability testers. Fiber size 

and pore size in MB webs are difficult to measure by optical microscopy or other methods. However, they can be determined in 

fibrous products from the air flow rate through the web. 

Introduction 

Melt blowing is a one step process to make microfiber webs directly from polymer resin. Melt blown webs have been developed for 

a large variety of applications, such as filters, operation gowns, wipes, oil absorbents, and battery separators, etc. All utilize the 

advantage of the microfibers which result in a breathable barrier fabric. Fiber size is a very important web property, which 

dominantly governs the filtration efficiency of the webs. The microfiber size of a MB web is difficult to measure using an optical 

microscope due to the fact that the fiber size is only slightly larger than the visible wavelength and no sharp edge is defined because 

of the light diffraction. It is time-consuming, tedious, and expensive to measure the fiber size by scanning electron microscopy 

although it is the most commonly used technique at the present time. Pore size is another important melt blown web property, which 

determines the web applications as liquid filters and battery separators. It can be determined using a porometer. Again, it is 

expensive and time-consuming. In this paper, the determination of fiber size and pore size of melt blown webs using air flow 

technique is discussed. It is a quick and accurate method at least for the nonwovens mentioned. 

Background 

Several relationships between pore size and fiber size in fibrous 

materials have been shown by earlier researchers. For metal fibrous 

mats, Goeminne [1] showed the relationship between largest pore size 

(da) and fiber size as 

(1) 

Figure 1 

RELATIONSHIP BETWEEN MEASURED FIBER SIZE 

(SEM) AND EFFECTIVE FIBER SIZE AS 

ESTIMATED USING DATA FROM THE 

TSI FILTER TESTER 

where D is the fiber size and is the mat porosity. He also showed the 

relationship between mean pore size (d m ) and fiber size for porosity less 

than 0.9 as 

(2) 

Wrotnowski [2] showed the relationship for felt mat as 

file:///D|/WWW/inda/subscrip/inj99_2/tsai.html (1 of 8) [3/21/2002 5:13:51 PM]


(3) 

where DEN is fiber denier, x is felt packing density, and y is fiber 

density. 

Equations 1-3 show that there is a relationship between pore size and 

fiber size by packing density for fibrous mats. One parameter, either 

fiber size or pore size, can be determined if the other is determined. Fiber 

fineness and pore size can be determined by air flow technique. The 

fineness of cotton fibers determined by the Micronaire test [3] is an 

example. This test measures the resistance of the air flowing through the 

fibers in a bulky form. The air resistance is from the friction of the air 

with the fiber surface. The air resistance increases as the fiber surface 

increases. Finer fibers have larger surface area than coarser fibers for a 

given amount of mass. Another example is the measurement of 1st and 

3rd bubble points reported by Wagner [4] who showed that there was an 

excellent agreement of bubble points measured by several companies 

using different flow methods. This paper will discuss how fiber size and 

pore size of melt blown webs can be determined by air flowing through 

them. 

Theory 

The general equation for fluid flow through porous medium was described by Brinkman [5] as 

where p = fluid pressure on the medium 

µ = air viscosity 

k = air permeability 

v 0 = air superficial velocity 

= air density 

(4) 

Figure 2 

RELATIONSHIP BETWEEN MEASURED FIBER 

SIZE (SEM) AND EFFECTIVE FIBER SIZE AS 

ESTIMATED USING DATA FROM THE FRAZIER 

AIR-PERMEABILITY TESTER 

The gravity term ( g) can be discarded because air density is negligible compared to the medium resistance to the air flow. The 

turbulent term, the third term on the right side of the equation, can be neglected at a low air flow rate. Therefore, Equation 4 is 

reduced to Darcy's law for air flowing through porous materials at low air flow rate, which is 

(5) 

For fibrous webs, a porous material, if the fibers are transverse to the flow direction, the air flowing through the web will obey 

Darcy's law and the following equation must be obeyed [6] 

(6) 

where c is web packing density (a ratio of the fiber volume to that of the web in which the fiber is composed of) , A is the web 

cross-sectional area subjected to the air flow, R is the average fiber radius, Q is the air flow rate and h is the web thickness. 

Several forms of the function of c were given, e.g., Langmuir [7] gave the function of c as 



(7) 

Davies [6] made an experimental correction in Equation 7 and provided the following relation for packing density in the interval of 

0.006 < c < 0.3 

(8) 

(9) 

where d f is the average fiber size 

v is the fluid flow velocity. 

If the fiber cross-sectional area is irregular rather than circular, the fiber size (d f ) in Equation 9 is called effective fiber size, a 

parameter that dominantly determines the air filtration efficiency of a fibrous material. Depending on the fiber shape and the fiber 

size distribution in the web, effective fiber diameter varies from the average of the actual fiber size. However, effective fiber size is 

always larger than the average of the actual fiber size [6]. 

The effective fiber size can be calculated from Equation 9 if the pressure drop is determined from a laminar flow through the fibrous 

medium. The actual fiber size can be obtained from the corresponding curve for the effective fiber size and actual fiber size. This 

technique will be described in a later section of this paper. 

We now continue on the theory of pore size determination. For the fluid flowing inside a circular pipe, Darcy's law becomes 

Hagen-Poisulla's law, which is described by the following equation 

(10) 

in which the coefficient in laminar flow is 32/D 2 in Darcy's law for fluid flowing through porous materials. The fluid velocity inside 

the web is higher than the web superficial velocity and should be increased by 1/ , where is the web porosity. Together with the 

modification of the fluid flow by turtosity factor (T), a term that describes the increase of the fluid flowing path through porous 

materials, Equation 10 becomes 

(11) 

where z is the web thickness and the other terms were defined before. Equation 11 is ASTM F902 Standard [7] to obtain the average 

circular-capillary-equivalent pore size by laminar air flow. By combining Equations 9 and 11, another relationship between pore 

size and fiber size can be obtained, i.e. 



Equation 13 says that average circular-capillary-equivalent pore size is related to effective fiber size by a function of web packing 

density g(c). This agrees with Equations 1-3 found by the previous researchers for fibrous mats. 

Now the air permeability in Darcy's law for air flowing perpendicularly through a flat web, i.e. one-dimensional flow, can be 

obtained by combining Equations 5 and 9 as 

(14) 

in which for one-dimensional flow, 

Equation 14 says that air permeability is only a function of fiber size and the function of packing density, and pore size term is not 

apparently involved. However, pore size is an implicit function of fiber size and packing density function. 

Experimental 

A TSI Automated Filter Tester was used to measure the web filtration efficiency. It also displayed the pressure drop across the web 

at a constant air flow rate, 5.3 cm/s in this study. A Frazier air permeability tester was used to measure the air flow rate at constant 

web pressure drop, 12.7 mm of water according to ASTM Method D737 (10). Pressure drop and air flow rate measured from both 

instruments were employed to calculate the effective fiber size by Equation 9. Four MB webs were produced at a large range of 

primary air velocity (60%, 70%, 80% and 90% air valve opening) from Accurate Products melt blowing line at the University of 

Tennessee to obtain a broad range of fiber size. A curve as shown in Figures 1 and 2 that corresponds the effective fiber size to SEM 

fiber size can be obtained. This curve is therefore used to find the actual fiber size, i.e. SEM-equivalent fiber size, once the effective 

fiber size is obtained. Effective fiber size is not the average of actual fiber size as described previously. However, it is an excellent 

"yard stick" of actual fiber size. Effective fiber size is a function of fiber shape and fiber size distribution of a web. The curve 

relating SEM-equivalent fiber size to actual fiber size is not a universal curve for all fibrous webs, i.e. the curve changes when either 

the fiber shape or the fiber size distribution changes. However, for typical melt blown webs, they have similar fiber shape and fiber 

size distribution. Therefore, the relating curve is excellent for all typical melt blown webs. 

Three other melt blown webs with a broad range of fiber sizes were produced by changing the die temperature and primary air 

velocity. The actual fiber size of this group of webs was obtained from the corresponding curves in which the effective fiber size was 

calculated from the data obtained using TSI tester and Frazier tester. The actual fiber size was compared with those measured using 

the scanning electron microscope. 

The pressure drops obtained at constant air flow rate for different melt blown webs having different fiber size from TSI tester were 

used to calculate average circular-capillary-pore size. The results were compared with the mean flow pore size measured from 

Coulter Porometer II based on the equation that describes the capillary flow in a tube [11] 



(15) 

where D is the pore size, g is the surface tension and q is the contact angle. Contact angle is zero for a wet-out sample by the fluid 

used in the porometer. Therefore, Equation 15 becomes 

(16) 

Surface tension is constant and can be determined for the liquid used to wet out the sample. Therefore, pore size is inversely 

proportional to the applied air pressure. 

Results and discussion 

Figures 1 and 2 are the curves that relate the actual fiber size obtained from the scanning electron microscopy to effective fiber size 

derived from the data obtained from TSI and Frazier testers, respectively. Theoretically, as long as the air flowing through the webs 

is laminar, these two curves should be equal for the fibrous materials such as MB webs having similar cross-sectional shape and fiber 

size distribution. Actually, some deviation occurs and it is explained in the later paragraph. 

A typical melt blown web has an average fiber size of approximate 2 mm. The Reynolds number at TSI standard air flow rate, 5.3 

cm/s, is 

(17) 

where D is the fiber size. The Reynolds number for a typical melt blown web (Re = 0.0067) is much lower than the critical Reynolds 

number (Re = 1.0) for a turbulent flow through a porous medium. Therefore, the air flow through the fabric is laminar. 

The pressure drop sensitivity of the instrument at different flow rate presents a reason that the two curves derived from two different 

testers did not completely agree. Different curves mean that different air flow rates may provide different effective fiber sizes. The 

corresponding actual fiber size obtained from different curves should be equal for the same web. However, the fabric is compressed 

by the pressure difference in the upstream and downstream of the fabric. Therefore, testing at different pressure drops attributed to 

the distortion of the web presents another deviation on the actual fiber size obtained from effective fiber size from different testers. 

The actual fiber size obtained from Figures 1 and 2, measured by TSI and Frazier, respectively, for a group of samples produced at 

different process conditions is listed on Tables 1 and 2 and is also compared with that measured from scanning electron microscopy. 

The maximum error from TSI was 10.8% and 19.1% from Frazier. This amount of error is reasonable and acceptable for MB webs 

because they have a large range of fiber size distribution (CV%=50%) and their fiber size is too small to be measured by any other 

technique. Melt blown fiber size measured from different instruments, e.g. optical microscope and SEM, or by different technicians 

usually contribute to an error that is greater than 20%. 



Table 1 

COMPARISON OF FIBER SIZE OBTAINED 

FROM EFFECTIVE FIBER SIZE BY TSI TESTER 

AND SEM FIBER SIZE 

Table 2 

COMPARISON OF FIBER SIZE OBTAINED 

FROM EFFECTIVE FIBER SIZE BY FRAZIER 

AND SEM FIBER SIZE 

Fiber Size 

From 

FIBER SIZE 

From 

Effective Effective SEM 

Effective Effective SEM 

Fiber Size Fiber Size Fiber Size Error 

Fiber Size Fiber Size Fiber Size Error 

Sample mm mm mm % Sample mm mm mm % 

1 4.84 1.92 1.93 0.5 1 5.65 1.76 1.93 8.7 

2 7.82 3.13 2.97 5.3 2 9.09 3.54 2.97 19.1 

3 10.13 4.56 5.12 10.8 3 11.38 5.62 5.12 9.9 

Figure 3 

COMPARISON OF MEASURED PORE SIZE 

(MFP = 

MEAN FLOW PORE SIZE FROM COULTER 

POROMETER II) AND 

COMPUTER-CALCULATED 

PORE SIZE (ACCP - AVERAGE CIRCULAR 

CAPILLARY PORE SIZE FROM TSI DATA) FOR 

A 

VARIETY OF MELT BLOWN WEBS 

(pp = polypropylene, lldpe = linear low density 

polyethlyene, pet = polyethylene terephthalate) 

Figure 4 

COMPARISON OF MEASURED PORE SIZE 

(MFP 

= MEAN FLOW PORE SIZE FROM 

COULTER 

POROMETER II) AND 

COMPUTER-CALCULATED 

PORE SIZE (ACCP = AVERAGE CIRCULAR 

CAPILLARY PORE SIZE FROM TSI DATA) 

FOR A 

GROUP OF 34-G/M 2 MELT BLOWN WEBS 

Figure 4 shows the pore size relationship between that measured from Coulter Porometer II and that derived from the air flow rate 

obtained from the TSI Filter Tester for a group of MB webs having different fiber size and pore size. They had a good agreement for 

the pore size smaller than 50 mm. Pore size from Coulter Porometer II may not be stable for large pore size and the low pressure 

drop in TSI from the webs of large pore size may be out of the sensitivity of the instrument sensor. Figure 4 shows another plot of 

the pore size measured from Coulter Porometer II and calculated using air flow rate from TSI Filter Tester for a set of nine typical 34 

g/m 2 (1 oz/yd 2 ) melt blown webs produced at different time. 

Figure 5 shows the disagreement of air permeability measured from the Frazier air permeability tester, TSI filter tester and Coulter 



Porometer II at different pressure drops and normalized to that of Frazier 

tester (12.7 mm of water). The normalized air permeability will be lower 

than that measured from Frazier tester if the pressure drop measured from 

other testers was higher than Frazier tester because a higher pressure will 

compress more on the web as discussed before. Therefore, a lower air 

permeability will be measured. This is true for the normalized air 

permeability obtained from the Coulter Porometer II at a higher pressure 

drop as shown in the curves in Figure 5. The normalized air permeability 

from the TSI tester at a lower pressure than from Frazier tester shows a 

lower air permeability as illustrated in the same figure, and this reason is 

not known. It is observed that air permeability should be measured at the 

specified pressure drop rather than to convert the air permeability from 

another pressure drop by a theoretical equation, such as Equation 9, 

because of the different distortion of the web compression and hence 

packing density by different pressure across the web from the applied air 

flow rate. The higher the pressure across the web, the more the web 

packing density is distorted. Therefore, the normalized air permeability is 

reduced. 

Figure 5 

NORMALIZED AIR PERMEABILITY AS 

MEASURED USING FRAZIER, TSI AND COULTER 

POROMETER II TESTED FOR A GROUP OF 

34-G/M 2 MELT BLOWN WEBS 

Conclusions 

Air flow techniques provide a quick method to accurately calculate two 

important MB properties, fiber size and pore size. This method can be done 

on any air flow instrument if a laminar air flow through the web is 

provided. The Frazier air permeability tester and TSI filter tester were two 

instruments used in this paper for the determination of fiber size by air flow 

technique. They both show a good agreement with the fiber size measured 

from scanning electron microscopy. Air flow rate and pressure drop 

measured from the TSI instrument was also used to calculate the MB web pore size. The results had a good agreement with those 

measured by the Coulter Porometer II for the pore size less than 50 mm. Air permeability measured from the Frazier tester did not 

agree with that measured from other air flow testers and normalized to the constant pressure drop (12.7 mm of water) used in Frazier 

tester according to ASTM Method D737. 

Literature cited 

1. Goeminne, H., "The Geometrical and Filtration Characteristics of Metal-Fiber Filters - A Comparative Study," Filtration and 

Separation 1974 (August), pp. 350-355. 

2. Wrotnowski, A.C., Felt Filter Media, American Felt Co., Glenville, CT, 1968. 

3. Grover, Elliot B. and Hamby, D.S., Handbook of Textile Testing and Quality Control, Textile Book Publishers, Inc., A Division of 

Interscience Publishers, Inc., New York, 1960, pp. 212-220. 

4. Wagner, J. Robert, "The relationship of filter media 1st and 3rd bubble point and maximum pore size," TAPPI Journal, pp. 108, 

199-202, vol. 78, No. 4, 1995. 

5. Brinkman, H.C., Appl. Sci. Research, A1, 27-34, 81-86 (1947). 

6. Davies, C.N., Air Filtration, Academic Press, London, 1976. 

7.Langmuir, I., "Report on Smokes and Filters," Section I. U.S. Office of Scientific Research and Development, No. 865, Part IV 

(1942). 

8. Hinds, William C., Aerosol Technology, John Wiley & Sons, New York, 1982. 

9. ASTM F902, "Standard Practice for Calculating the Average Circular-Capillary-Equivalent Pore Diameter in Filter Media from 

Measurements of Porosity and Permeability," American Society for Testing Materials, 1926 Race St. Philadelphia, PA 19103, 1984. 

10. ASTM Method D737, "Standard Test Method for Air Permeability of Textile Fabrics," American Society for Testing Materials, 

1926 Race St. Philadelphia, PA 19103, 1984. 

11. Adamson, Arthur W., Physical Chemistry of Surfaces, Interscience Publishers, a division of John & Sons, New York, 1967. 



This paper was originally submitted for publication in the TAPPI Journal. The INJ editors and publishers wish to express their 

appreciation to TAPPI for their support and encouragement. 

INJ 




Bonding of Spunlace Fabrics 

Foamed Latex Bonding of 

Spunlace Fabrics To Improve 

Physical Properties 


By A. Shahani, Software Engineer for Bell Atlantic; D. A. Shiffler, Adjunct Associate Professor at the Nonwovens 

Cooperative Research Center; and S. K. Batra, the Charles A. Cannon Professor of Textiles at North Carolina State 

University, and Director of the Nonwovens Cooperative Research Center. 

Abstract 

Strength, abrasion resistance, load at 5% strain (modulus), and strain recovery of dry lay spunlace fabric are improved by the 

addition of small amounts (


Round Cross Section 

Figure 1 

TYPICAL MD TENSILE CURVES 

FOR POLYESTER FABRICS AT 

3600 kJ/kg FOR FOUR ADD-ON 

LEVELS (0,1.25, 2.5, 5%) 

Figure 2 

TYPICAL MD TENSILE CURVE 

FOR COTTON FABRICS AT 3600 

kJ/kg FOR FOUR ADD-ON LEVELS 

(0,1.25, 2.5, 5%) 

Figure 3 

TYPICAL MD TENSILE CURVE 

FOR ACRYLIC FABRICS AT 3600 

kJ/kg FOR FOUR ADD-ON LEVELS 

(0,1.25, 2.5, 5%) 

Figure 4 

MAXIMUM LOAD VS. ADD-ON (%) 

FOR POLYESTER FABRICS MADE 

AT THREE SPECIFIC ENERGIES 

(1800, 3600 AND 7100 kJ/kg 

Figure 5 


FOR COTTON FABRIC MADE AT 

THREE SPECIFIC ENERGIES 

(1800, 36000 AND 7100 kJ/kg) 

Figure 6 


FOR ACRYLIC FABRIC MADE AT 

TWO SPECIFIC ENERGIES (3550 

AND 7100 kJ/kg) 

Figure 7 

ELONGATION AT MAXIMUM 

LOAD VS. ADD-ON (%) FOR 

POLYESTER FABRICS MADE AT 


(1800, 3600, 7100 kJ/kg) 

Figure 8 


LOAD VS. % ADD-ON FOR 

COTTON FABRICS MADE AT 


(1800, 3600, 7100 kJ/kg) 

Figure 9 


LOAD VS. % ADD-ON FOR 

ACRYLIC FABRICS MADE AT 

TWO SPECIFIC ENERGIES ( 3550, 

7100 kJ/kg) 

file:///D|/WWW/inda/subscrip/inj99_2/spunlace.html (2 of 9) [3/21/2002 5:13:02 PM]


Figure 10 

LOAD AT 5% STRAIN VS. % 

ADD-ON FOR POLYESTER 

FABRICS MADE AT THREE 

SPECIFIC ENERGIES (1800, 3600, 

7100 kJ/kg) 

Figure 11 


ADD-ON FOR COTTON FABRICS 

MADE AT THREE SPECIFIC 

ENERGIES (1800, 3600, 7100 kJ/kg) 

Figure 12 


ADD-ON FOR ACRYLIC FABRICS 

MADE AT TWO SPECIFIC 

ENERGIES (3600, 7100 kJ/kg) 

Figure 13 

BENDING RIGIDITY VS. % 




7100 kJ/kg) 

Figure 14 




ENERGIES (1800, 3600, 7100 kJ/kg) 

Figure 15 





Figure 16 

CORRELATION TEST PLOT FOR 

BENDING RIGIDITY AND LOAD 

AT 5% STRAIN 

Figure 17 

ABRASION RESISTANCE VS. % 




7100 kJ/kg) 

Figure 18 




ENERGIES (1800, 3600, 7100 kJ/kg) 



Figure 19 




ENERGIES (1800, 3600, 7100 kJ/kg) 

Figure 20 

TYPICAL RECOVERY CURVE 

(POLYESTER, 1800 kJ/kg, 2.5% 

ADD-ON) 

Figure 21 

RECOVERY (%) VS %ADD-ON 

FOR DRY POLYESTER FABRICS 


ENERGIES (1800, 3600, 7100 kJ/kg) 

Figure 22 

RECOVERY (%) VS %ADD-ON 

FOR DRY ACRYLIC FABRICS 



Figure 23 

RECOVERY (%) VS % ADD-ON 

FOR DRY COTTON FABRICS 


ENERGIES (1800, 3600, 7100 kJ/kg) 

Figure 24 

EFFECT OF FABRIC WETTING ON 

RECOVERY FOR 7100 kJ/kg 

COTTON FABRIC 

Fibers were carded using a roller top card, cross-lapped on a jigger lattice cross lapper to achieve a final web basis weight of 

50 g/m 2 . Webs of each fiber type were then hydroentangled (Honeycomb unit) in a second step at three energy levels (1800, 

3600 and 7100 KJ/kg) and dried. Next we used a Gaston County Foaming System in conjunction with a horizontal applicator 

and roll mechanism [8] to apply foam binder. Foam was generated and applied through a pressure applicator. A driven 

presser roll was used to force the foam to penetrate the substrate resulting in quantitative application. 

The foam mix consisted of water, acrylic latex binder and foaming agent. There were two critical requirements for a foam 

with adequate stability to achieve both uniform surface coating and adequate fabric penetration: 1) a foam half life in air of 4 

to 5 minutes achieved by controlling foaming agent concentration at 0.5 % bwt, and 2) a 10:1 blow ratio of air to liquid in the 

generator. 

Table 2 

EXPERIMENTAL DESIGN 

Specific 

Energy 

Fiber (kJ/kg.) % Add-on Binder Type 

Acrylic, Cotton, Polyester 1800 0, 1.25, 2.5, 5.0 Rhoplex(r) NW-1715 




Table 2 summarizes the experimental design. Because mechanism changes fiber to fiber were anticipated, a full statistical 

matrix was not used. To provide statistical significance, and to measure the degree of repeatability, a replicate set of samples 

was made at the 1.25, 2.5 and 5.0% add-on levels. A total of 36 replicate samples were made. 

Fabric breaking load, % elongation at maximum load, and the load at 5% strain were measured on an Instron 4400R using the 



ASTM D-1682 strip tensile test method [9]. Each sample tested was of size 2.54 cm x 20.32 cm., speed of testing was 30.48 

cm/min, and gage length was fixed at 7.62 cm. Bending rigidity was measured by the Cantilever principle using ASTM 

D-1388-64 cantilever bending test [10]. The samples used were 2.54 cm x 20.32 cm. Abrasion resistance was measured on a 

Taber Abrasion Tester using ASTM D-3884-92 [11] standard abrasion test method. Four fabric samples, each 12.7 cm x 12.7 

cm dimensions, were tested. Two CS-10 abraders attached to 500 gm weight were used to abrade the samples. The vacuum 

level was kept constant at 100 mm of Hg for all samples. The abrasion resistance was measured as the number of cycles of 

abrasion the fabric withstood until its surface was completely abraded. 

Wet and dry recovery tests were performed on the Instron. Sample size was 2.54 cm x 20.32 cm, the gage length was fixed at 

7.62 cm, and the strain rate was 400% per minute. Five samples of each fabric in the machine direction were stretched to 5% 

strain and were then relaxed at a rate of 400% per minute. Load vs. Strain (%) curves were then plotted for each fabric and 

the recovery (%) was then calculated from the graph for each specimen by 

R= (R s /I s ) x 100 (1) 

Where: 

R = % Recovery 

R s = Recovered strain, % 

I s = Initial applied strain, % 

The ratio of machine direction (MD) and cross direction (CD) values for dependent variables which are direction sensitive 

(for example break strength and elongation) was nearly constant, and their response to the independent variables was 

consistent, so MD and CD values for these variables were averaged to simplify the analysis. Results from the two replicate 

data sets were statistically indistinguishable at the 5% level in the t-test so replicate and initial sets were further averaged to 

better display property trends. 

Results 

A. Stress / Strain Curves 

Figures 1-3 present the effect of binder addition on fabric MD stress strain curves for the intermediate level of 

hydroentanglement energy for all three fibers. The effects illustrated were typical of all fabrics tested and exhibit: 

● increasing break strength with increasing binder level 

● decreasing break elongation with increasing binder level 

● a more erect strain curve with higher initial modulus at higher binder levels. 

These observations are all consistent with improved fiber bonding. 

B. Maximum Break Load 

Fibers differ in their ability to convert water jet energy into entangled fiber bonds and so binder free maximum break load 

differs greatly. For example, when 3600 kJ/kg is applied to polyester, cotton and acrylic fibers break loads for the fabrics 

were 48, 14 and 4N/2.54cm width respectively. Webs of acrylic fiber hydroentangled at 1800 kJ/kg acted more like 

unbonded bats than fabric, and were excluded from further analysis. Figures 4, 5 and 6 illustrate the effect of adding foam 

binder to the system. In general, the poorer the binder free hydroentanglement, the greater the relative improvement realized 

with foam bonding. 

Elongation at Maximum Load 

Elongation at maximum load in nonwovens is, in general, inversely related to maximum load carrying capacity. As indicated 

in Figures 7, 8 and 9 the change in elongation when low levels of binder are added is greatest for those fibers which are 

poorly bonded by hydroentangling. 

Load at 5% Strain 

The stress/strain curves of nonwovens are highly non-linear (Figures 1, 2 and 3) so the modulus is difficult to define. In this 

study, nearly all the fabrics had linear curves up to 5% strain, so comparison of load at this strain level should provide insight 

into fabric response to strains encountered in converting to the final commercial article. 

As indicated in Figures 10, 11 and 12 addition of extremely small levels of binder dramatically increases fabric initial 

modulus no matter how efficiently the fabric is hydroentangled in terms of break strength and elongation. This improvement, 

which ranges between 2 to 6X, has potential for improving fabric processability during the converting process. 



E. Fabric Bending Rigidity 

Bending rigidity was used as a rough measure of fabric hand. Rigidity increased roughly proportionally with binder loading 

for all three fibers (Figures 13, 14 and 15). Therefore one expects that fabric hand will of necessity need to be traded for the 

beneficial improvements in tensile properties and abrasion resistance. 

Bending rigidity can also be estimated from tensile behavior using the classical equation: 

M = E I (2) 

Where M is the bending rigidity, E is the fabric Young's modulus, and I is the fabric moment of inertia, in this case a 

constant. 

Assuming that Young's modulus is proportional to load at 5% strain (L 5% ) we have: 

E =k 1 ( L 5% ) (3) 

where k 1 is a constant. 

So, the bending rigidity becomes: 

M = k 1 (L 5% ) (4) 

Figure 16, which contains plots all data points for all three fibers at all binder levels, confirms these assumptions. We 

believe, therefore, that a simple determination of load at 5% strain can be used to characterize bending rigidity, possibly with 

greater accuracy than the rather error prone direct measurement itself. Multiple R=0.95, R-square=0.90 

Fabric Abrasion Resistance 

Fabric abrasion effects are dominated by the presence of poorly bonded surface fibers which become entrapped in the 

abrading material, increase the intensity of the abrading surface, and lead to early fabric failure. Addition of extremely small 

amounts of binder provide a 1.8 to 2X improvement in fabric performance for all three fiber systems at all energy levels 

(Figures 17, 18 and 19). The mechanism appears to be one of reducing the number and length of poorly bonded surface 

fibers. 

Fabric Recovery from Small Strains 

In the course of processing from roll goods to finished article, nonwoven fabrics are subjected to small strains in machines 

which are much stronger than the fabric. To preserve dimensional stability it is desirable that all strain is recovered by the 

fabric. In fact, this is rarely the case. We studied this by straining our fabrics 5% and determining the amount of strain 

recovered as the load is reduced to zero. Figure 20 is a typical stress strain curve for such a trial. 

The addition of small amounts of binder to both polyester and acrylic fabrics significantly increased recovery (Figures 21 

and 22). In the case of polyester 2.5% binder increased recovered strain from about 60 to 85%. For acrylic fabrics the 

improvement was from 55 to 80%. Dimensional stability of both fabrics should therefore improve. 

The curious increase in load as strain is decreased from its maximum is a commonly observed effect having to do with a lag 

between the response time of the instrument force and strain measurements. This could be eliminated with slower strain rates 

or software modifications taking into account the force measurement response time. 

The behavior of cotton was different. As indicated in Figure 23, strain recovery for binder-free cotton fabric was relatively 

good, particularly at the higher energy levels. Addition of binder did not provide the dramatic improvement encountered with 

the synthetic fibers. 

There is some evidence that this is a hydrogen bonding effect. First, raw cotton was used, and the recovery improved 

significantly between the two lowest energy levels suggesting that washing off the natural finish oils caused the effect. 

Secondly, adding water, which breaks hydrogen bonds, reduced recovery from 80 to 70%, but insufficient trials were carried 

out to eliminate lubrication and water/binder interaction effects. 

The picture suggested is that bond sites are composed of three types of bonding: 

● frictional 

● chemical, from the resin 

● hydrogen, from the cotton. 



Additional work aimed at elucidating this mechanism, as well as using small amounts of cotton, or other cellulosics in 

hydroentangled fabrics to enhance strain recovery, appears justified. 

Binder T g 

A two sample t-test with unequal variance was used to compare two binders, Rhoplex® NW-1715 and Rhoplex® NW 1845, 

at the intermediate 3600 kJ/kg hydroentanglement energy level. The t tests showed that the two binders were not statistically 

distinguishable for any of the dependent variables tested. We suspect that at these low binder levels, the modulus of the 

binder itself is less important than in saturation bonding at the 10 to 20% binder level. 

Discussion of Results 

Addition of small amounts of binder in foam form involves trading one physical property off against another. In general, 

adding binder increases break strength, modulus, abrasion resistance and strain recovery at the expense of fabric stiffness and 

elongation. 

Table 3 

SOME PROPERTY BALANCE CHOICES FOR HYDROENTANGLED POLYESTER NONWOVEN FABRICS 

Tensile Properties 

Break 

Abrasion 

Resistance 

Bending 

Specific Energy, 

Break Load Elongation Load at 5% Cycles To % Strain 

Rigidity 

kJ/kg % Binder N/2.54 cm (%) N/2.54 cm Failure Recovery 

mg-cm 

7100 0 48 82 0.4 77 78 

35 

1800 1.25 40 63 1.3 62 73 

79 

7100 1.25 61 74 3.0 140 77 

90 

7100 5.00 64 68 6.2 190 86 

290 

The tradeoffs appear particularly interesting for the polyester fabric. Some typical property balances are presented in Table 3. 

In this case, hydroentaglement energy can be decreased by a factor of 4 and a satisfactory fabric obtained by adding as little 

as 1.25% binder. Further improved properties can be obtained at the expense of fabric rigidity by increasing either binder or 

energy. 

Table 4 

SOME PROPERTY BALANCE CHOICES FOR HYDROENTANGLED COTTON NONWOVEN FABRICS 


Break 

Abrasion 

Resistance 

Bending 



Rigidity 


mg-cm 

7100 23 55 1.8 82 80 

82 

1800 1.25 7 67 0.5 20 71 

71 

7100 1.25 25 55 2.4 65 76 

120 

7100 5.0 28 51 5.0 120 78 



170 

Table 5 

SOME PROPERTY BALANCE CHOICES FOR HYDROENTANGLED ACRYLIC NONWOVEN FABRICS 


Break 

Abrasion 

Resistance 

Bending 



Rigidity 


mg-cm 

7100 0 34 76 0.4 35 56 

33 

3600 1.25 15 69 1.1 39 80 

75 

7100 1.25 45 64 1.9 67 -- 

75 

7100 5.00 49 57 6.4 98 89 

300 

Similar property balance choices for cotton and acrylic are presented in Tables 4 and 5. Cotton is quite interesting in that low 

levels of binder provide less improvement than with the synthetic fibers. We suspect this is caused by hydrogen bonding. 

Summary and Conclusions 

The addition of binder to hydroentangled fabrics of polyester, cotton and acrylic significantly increases the break strength, 

load at 5% strain, abrasion resistance, and strain recovery, but the bending rigidity of the fabric increases. A synergistic effect 

of the two bonding mechanisms is greatest in fabrics that are poorly hydroentangled and have no possibility of hydrogen 

bonding. The effect of binder add-on tends to even out with well hydroentangled and hydrogen bonded fabrics. Fiber 

properties and type also play a significant role in the hydroentangling process; polyester hydroentangles very well while 

cotton and acrylic do not. The effect of binder choice on the properties was found not to be significant factor at these low 

add-on levels. A nonwoven manufacturer can use this experimental data to optimize end-use properties for his products by 

balancing the trade offs between the several physical properties. 

References 

1. Sontara Spunlaced Fabric Finishing, Research Disclosure, No. 138, Oct., 1975 by Dupont. 

2. Properties and Processing: Sontara® Spunlaced Fabrics of 100% Polyester Fiber, DuPont Technical Information, 

Sontara® Spunlaced Fabric Bulletin SN-1, June 1979. 

3. Johns, M. M., and Auspos L. A., "The measurement of the Resistance to Disentanglement of Spunlaced Fabrics," INDA 

Technical Symposium, 158-173 (1979). 

4. Guenther, H. W., Barnes C. G., May R. E., and Riggins P. H., "Nexus® Spunlaced Formed Fabrics," Modern Textiles, 

40-48, (Dec. 1973). 

5. Brooks, B. A., Kennette J. W., and Buyofsky C. C., Lightly Entangled and Dry Printed Non Woven Fabrics and Methods 

for Producing the Same, U.S. Patent 4,623,575 issued to Chicopee, Nov. 18, 1986. 

6. Viazmensky, H., Richard C. E., and Williamson, J. E., Water Entanglement Process and Product, U.S. Patent 5,009747, 

issued to C.H. Dexter, April 23, 1991. 

7. Schortmann, W. E., Microsized Fabric, U.S. Patent 4,449,139, issued to The Kendall Company, February. 12, 1985. 

8. The CFS Foam Application, Patents Issued or Pending, (Personal Communication Gaston County Dyeing Machine 

Company), (1995). 

9. ASTM D 1682, Test Method for Breaking Load and Elongation of Textile Fabrics. 

10. ASTM D 1388-64, Test Methods for Stiffness of Fabrics. 

11. ASTM D 3884-92, Standard Test Method for Abrasion of Textile Fabrics (Rotary Platform , Double Head Method) 

- INJ 






Fiberglass Surface 


Fiberglass Surface and Its Electrokinetic Properties 

By Daojie Dong, PhD, Senior Scientist, 

Owens Corning Science & Technology Center, Granville, Ohio 

Abstract 

The surface charge of fiberglass is an important variable for fiber dispersion and web formation in a wet-laid process. This 

paper presents an overview of the glass surface electrokinetic properties as well as their applications for improving the 

quality of wet-laid nonwovens through good fiber dispersion and uniform web formation. The paper addresses the basic 

concepts used in electrokinetic characterization of glass surface and briefly discusses the available techniques for zeta 

potential measurement. 

Introduction 

Wet-laid glass nonwovens, or wet-formed glass mat (WFGM), began appearing in the 1960s in small amounts. Rapid growth 

in the production of WFGM has occurred since ~1980 when it was introduced into glass-based roofing shingles. It is 

predicted that a moderate growth of the WFGM production will continue in the foreseeable future. 

The WFGM process primarily deals with the dispersion of fiberglass in white water and the subsequent formation of a glass 

web on a forming fabric while being de-watered. The electrokinetic properties (the term "electrokinetic" means the combined 

effect of motion and electrical phenomena) of a glass surface play an important role in fiber dispersion/web formation and 

may directly contribute to the quality of WFGM. 

This paper presents an overview of the electrokinetic properties of glass surface and their applications for improving WFGM 

quality through good fiber dispersion and uniform web formation. The paper consists of two parts: part one discusses 

fundamentals of fiberglass surface and its electrokinetic properties as well as their effect on a colloidal system that contains 

fiberglass; and part two introduces available techniques for the measurement of zeta potential. Helpful references have been 

listed at the end of this article [1-7]. 

Part I: ELECTROKINETIC PROPERTIES OF FIBERGLASS SURFACES 

Fiberglass/Water Interface and Electrical Double layer 

Bulk glass does not exhibit electrostatic charges. When brought into contact with water (in liquid or in air), however, glass 

surface generally exhibits net negative charge. The negative charges may originate from surface ionization and surface ion 

adsorption, etc. 

The net charges on a fiberglass surface influences the distribution of nearby ions in a polar medium: ions of opposite charge 

(called counter-ions) are attracted to the surface and ions of like-charge (called co-ions) are repelled away from the surface. 

Thermal motion is another factor that affects the distribution of charged species in the fiberglass/water interface region, and 

tends to distribute charged species in a diffused manner. The overall effect of the electrostatic interaction and thermal motion 

results in an equilibrium distribution (Figure 1) of charged species in the interface region and forms a so-called electrical 

double layer (EDL). 

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Figure 1 

ELECTRIC DOUBLE LAYER CONSISTS OF A 

CHARGED SURFACE AND A LAYER OF EXCESS 

COUNTER-IONS DISTRIBUTED 

IN A POLAR MEDIUM 

Figure 2 

STERN MODEL TREATS AN EDL AS A CHARGED 

SURFACE, A COMPACT LAYER (STERN LAYER) OF 

COUNTER-IONS HELD TIGHTLY TO THE SURFACE, 

AND A DIFFUSE LAYER OF IONS 

Figure 3 

pH EFFECT ON THE ZETA POTENTIAL OF BARE 

AND SIZED FIBERGLASS SURFACE. (ISOELECTRIC 

POINT IS THE pH AT WHICH ZETA POTENTIAL 

EQUALS TO ZERO.) 

In Figure 1 each "-" sign represents either a negative charge on the fiberglass surface or an anionic ion in the fluid phase, and 

a "+" sign stands for a positive charge on the surface or a cationic ion in the fluid phase. The "-" signs are predominant on the 

surface, indicating fiberglass surface is negatively charged. The bulk fluid far away from the surface will not "feel" the 

influence of surface charges, so it is electronically balanced. In between the negatively charged glass surface and the neutral 

bulk phase, there exists a layer of fluid that contains excess cationic ions (i.e. more cationic ions than anionic ions). Figure 1 

schematically shows that an electrical double layer consists of a charged surface and a layer of excess counter-ions 

distributed in a polar medium. 

There are several models that deal with the distribution of ions in an EDL and the magnitude of electrical potential near a 

charged surface. Helmholtz model [2] treats the EDL as "two sheets of charges:" a charged surface and a layer of 

counter-ions that is held fixed to the surface. Gouy-Chapman model [8-10], as shown in Figure 1, treats the EDL as a 

charged surface plus a diffused layer (Gouy layer) of counter-ions. Stern-Graham model [11] is a combination of the two 

above and is widely accepted as the representation of the EDL structure. 

Figure 2 illustrates the Stern-Graham model: an EDL consists of a charged surface, a Stern layer (a compact layer of 

counter-ions held tightly to the surface) and a diffuse layer of ions in a polar medium. While the thickness of the diffuse layer 

may vary widely, the Stern layer is typically very thin (approximately a monolayer). 



Surface Potential and Zeta Potential 

Figure 2 also introduces a concept of "shearing surface," which is similar to the term of "boundary layer" used in 

fluidynamics. For example, when a charged glass surface is moving in a medium (e.g. white water), a layer of medium 

(boundary layer) will attach to it and move with it. So this motion creates a shearing surface relative to the stagnant fluid 

phase (see schematic illustration in Figure 8 in Part II). 

Surface potential and zeta potential are two different concepts. In practice, however, zeta potential is often used as a 

"synonym" of surface potential. As shown in Figure 2, unequal distribution of electrical charges gives rise to an electrical 

potential across the interface region. The magnitude of electrical potential varies and depends on where it is measured. 

Surface potential is the electrical potential measured at the fiberglass surface, and the electrical potential determined at the 

shearing surface is termed as zeta potential. 

As the distance away from the charged surface increases, the electrical potential (magnitudeNote) decreases. The electrical 

potential decreases linearly across the Stern layer and gradually in the diffused layer. As shown in Figure 2, it is obvious that 

the magnitude of zeta potential is generally smaller than that of surface potential. In practice it is very difficult to directly 

measure the surface potential, while the zeta potential can be easily determined (see Part II). For the sake of convenience, 

people tend to use zeta potential as a "synonym" of surface charges, although they are different concepts. 

pH Effect and Isoelectric Point (IEP) 

Figure 3 shows the typical electrokinetic behavior of a bare glass surface and a sized glass surface. The zeta potential of glass 

surface is strongly affected by pH. The pH at which the zeta potential equals zero is termed "isoelectric point" (IEP). At the 

IEP, the shearing surface is neutralized, so the repulsion between fibers is minimized. 

Note: Fiberglass has a negatively charged surface and a negative electrical potential. For the matter of convenience, in this 

article, an "increase" (or "decrease") of electrical (zeta) potential means an "increase" (or "decrease") in the MAGNITUDE 

of electrical (zeta) potential, unless otherwise specified. 

Bare glass surface (Figure 3) has an IEP of ~2. Variation in glass composition may change it slightly. At pHs above 2, bare 

fiberglass has a negatively charged surface and its zeta potential is always negative. As pH is increased, the magnitude of 

zeta potential of bare fiberglass increases. 

Practically, the zeta potential of fiberglass is of importance to its dispersability and to the stability of a colloidal system that 

contains glass fibers. For example, a zero or low (magnitude) zeta potential is needed in order (1) to efficiently pack wet 

glass fibers in a box for shipment or (2) to have a uniform web formation in the WFGM process. Bare glass has an IEP of ~2. 

At a low pH near 2, a strong acid condition, the fiber-fiber interactions can be minimized. However, there are lots of 

disadvantages to operate the WFGM process at low pHs. 

Owens Corning uses and supplies sized fiberglass that has an IEP around neutral pHs to facilitate fiberglass handling and 

glass web formation. Depending on the requirement for a particular process or the properties of a particular product, various 

sizing chemicals can be used to modify the electrokinetic properties of fiberglass. 

Interparticle Forces and Interparticle Potentials 

The electrokinetic behavior of fiberglass is of critical importance to the WFGM process. In general, there are four types of 

interparticle forces that affect fiber-fiber and fiber-white water interactions: electrostatic, van der Waals, hard sphere, and 

steric forces. The repulsive hard-sphere interactions become significant only when the two particles are getting very close to 

each other, therefore, are typically negligible in the case of WFGM process. The steric interactions certainly play a role due 

to the use of polymeric substances (in size formulation and in white water, e.g. polymeric viscosity modifier), but are also 

insignificant due to the relative large dimension of fiberglass (the diameter of fiberglass is much bigger than sub-micron 

colloidal particles). So, in the WFGM process, the fiber-fiber interactions are mainly determined by the overall balance of the 

van der Waals attraction and the electrostatic repulsion. Figure 4 schematically shows the potential energy versus the 

distance between two particles. Curve 1 is the electrostatic repulsion potential, Vr (Equation 1), curve 2 is the van der Waals 

attraction potential, Va (Equation 2) , and curve 3 is the net (total) potential energy, V (Equation 3). Since the van der Waals 

attractive potential (Equation 2) is predetermined for a given system, the electrostatic repulsion is the only factor that can be 

manipulated to vary the net potential energy between two fibers. 

Vr = f(s, S, D, 0, , b) [1] 

Va = f(s, S, D) [2] 

V = Va + Vr [3] 



where, 

s = particle size 

S = particle shape 

D = distance between two particles 

0 = surface potential 

= dielectric constant of the dispersing liquid 

b = thickness of EDL = 1/ 

= Debye parameter 

For the purpose of simplicity, the repulsive potential (force) between 

glass fibers is directly affected by the value of zeta potential. The 

higher the magnitude of zeta potential, the more repulsive the fibers 

are. As a result, the glass fibers will be more repulsive to each other. 

This helps fiber dispersion, but hurts the web formation in the WFGM 

process. On the other hand, the lower the magnitude of zeta potential, 

the less repulsive the fibers are. As a result, the glass fibers tend to get 

closer to each other. 

WFGM Process: A Special Case 

As indicated in Equation 1, the electrostatic repulsive potential energy 

is a function of particle size, shape, surface potential, the effective 

thickness of EDL, the distance between two particles, and the 

dielectric constant of a dispersing liquid. In many cases there might be 

Figure 4 

no solutions at all. Fortunately, the input glass fibers for the WFGM 

INTERPARTICLE POTENTIALS 

process are relatively large (large fiber diameter compared to sub-micron colloidal particles) with a relatively thin EDL. By 

approximation, the electrostatic repulsion between glass fibers can be estimated by Equation 4. The van der Waals attractive 

potential energy (Equation 2) is a simple function of the size and shape of two particles and the distance between them. With 

a spherical approximation, the attraction potential energy can be simply calculated by Equation 5. Therefore, the net (total) 

potential energy ((Equation 6) between two glass fibers is the sum of Equations 4 and 5. 

Vr = 1/2 ( r 0 2 /D) ln (1+e -(D-r) k ) (4) 

Va = -Ar/12(D-r) (5) 

V= Vr + Va (6) 

where, 

A = Hamaker (van der Waals ) constant 

r = glass fiber radius 

D = distance between two fibers 

0 = surface potential 

= dielectric constant 

= Debye parameter = [8 e 2 N a I/1000 kT] 1/2 

e = 4.0803 x 10 -10 esu 

Na = 6.02 x 10 23 moles-1 

k = 1.38 x 10 -16 ergs/ o k 

T = temperature in o k 

I = ionic strength = 1/2 Z 2 i C i 

Z i = valence of ion i 

C i = molar concentration of ion i 

For a given fiber diameter, the attractive energy (Equation 5) is fixed. By varying the zeta potential (surface potential) of 

fiberglass or the ionic strength of medium (e.g. white water), the repulsive energy (Equation 4) can be changed. As a result, 

the net potential (Equation 6), as schematically illustrated in Figure 5, can be changed. 



Conflict: Web Formation vs. Dispersion 

In the WFGM process, the dispersion of glass fibers in white water and the formation of a glass web in the forming zone are 

two conflicting concepts. To achieve good fiber dispersion, the fiber-fiber repulsion needs to be maximized. On the other 

hand, the fiber-fiber interactions need to be minimized in order to form a uniform glass web. Usually the solution is a 

compromise between the two. 

Generally, the author believes that the effect of electrokinetic properties on web formation is more critical than on fiber 

dispersion, and a good fiber dispersion can usually be achieved by the assistance of vigorous mechanical agitation and 

hydrodynamic means. As shown in Figure 5, we believe that the WFGM process typically deals with the secondary 

minimum on the net potential energy curve. For instance, in order to achieve a good web formation for improving mat 

quality, we compress the EDL and reduce the zeta potential of fiberglass by applying sizing chemicals on the surface of input 

glass fibers and by using chemicals in white water. As a result, the repulsion barrier is reduced and the glass fibers can come 

closer to each other (trapped in the secondary minimum, a potential well). To disperse fibers in white water, mechanical 

agitation, in addition to sizing and white water chemistry, plays an important role to "pull" the fibers out of the relative 

shallow "potential well. " 

Figure 5 

NET (TOTAL) INTERFACE POTENTIAL AS A FUNCTION OF 

THE DISTANCE BETWEEN TWO FIBERS 

Figure 6 

FIBERGLASS ZETA POTENTIAL AS A 

FUNCTION OF pH 

(Non-specific adsorption of sizing chemicals 

reduces the magnitude of zeta potential. The 

isoelectric point stays the same.) 

Manipulating of Zeta Potential: Specific and Non-specific Adsorptions 

The aforementioned principles clearly indicate that the electrokinetic property of fiberglass is very important to a WFGM 

process. Logically, the next question is how to manipulate it for the ease of process and the quality of products. Although 

what additives to use and how much to use are kept secret by the fiberglass suppliers (sizing chemistry) and the WFGM 

producers (white water chemistry), it is generally understood that the addition of ionic surfactants (either low molecular 

weigh substances or polymers) is an effective mean to manipulate the zeta potential of fiberglass. To answer the question, in 

general, there are several means that can be used to vary the electrokinetic behavior of fiberglass, such as, (1) variation in pH, 

(2) non-specific adsorption and (3) specific adsorption of charged chemicals on the fiberglass surface, etc. 

In non-specific adsorption, charged species are "physically" attracted to a charged fiberglass surface, but not chemically 

bonded to it. In specific adsorption, the charged species are attracted and chemically bonded to the fiberglass surface. As a 

rule of thumb, (1) variation in pH and (2) non-specific adsorption (Figure 6) can change only the magnitude of zeta potential, 

the IEP of the fiberglass surface will stay the same. On the other hand, (3) specific adsorption (Figure 7) of charged species 

on the fiberglass surface may change not only the magnitude of its zeta potential, but also its sign (from negative to positive 

or from positive to negative) and IEP (usually moving to a higher pH). 



Figure 7 

FIBERGLASS ZETA POTENTIAL AS A FUNCTION OF 

pH 

(Specific adsorption of chemicals can change the magnitude 

and sign of zeta potential. It also effectively changes the 

IEP.) 

Figure 8 

THE PRINCIPLE OF ZETA POTENTIAL 

MEASUREMENT TECHNIQUES IS BASED ON A 

RELATIVE MOTION AT THE SHEARING SURFACE 

Adsorption (specific or non-specific) of various charged substances on a fiberglass surface is an effective mean to vary its 

electrokinetic properties, and specific adsorption is usually more effective than non-specific adsorption. The effect of 

non-specific adsorption of charged chemicals is to "compress" the EDL, therefore, reducing the magnitude of zeta potential. 

As the concentration of charged species in a medium (sizing solution or white water) increases, the magnitude of fiberglass 

zeta potential will decrease (Figure 6). To obtain a very low magnitude of zeta potential at a given pH by non-specific 

adsorption, however, may have fundamental limits or may be very costly (a high concentration of charged species is needed). 

Also, as a general rule, the magnitude of zeta potential may approach zero, but non-specific adsorption does not change the 

IEP of fiberglass surface, nor the sign of its zeta potential. 

As shown in Figure 7, specific adsorption is very effective a mean to vary the electrokinetic properties of fiberglass surface. 

In specific adsorption, charged species (counter-ions) are chemically bonded to the fiberglass surface. When higher valence 

ions or a polymer that carries multiple charges are adsorbed on a fiberglass surface, it not only changes the fiberglass surface 

zeta potential, but also reverse the sign of its zeta potential and the value of its IEP (Figure 7). Therefore, specific adsorption 

is more effective and more flexible. By selecting proper charged chemical species and by controlling adsorption conditions, 

both the IEP and the magnitude of the zeta potential of a glass surface can be tailored for a good WFGM process. The 

mechanism that affects the rate of adsorption and the factors that affect of adsorption equilibrium are out of the scope of this 

article. 

The "variation in pH" alone plays a very limited role in terms of manipulating the WFGM process. Figure 3 (see the curve of 

bare glass) does show that pH strongly affects the zeta potential of (bare) fiberglass. Without using any chemical additives, 

however, a low zeta potential can be achieved only at a low pH near 2. On the other hand, pH is an important control variable 

when sized glass fibers are used. In order to achieve a good web formation, for example, we want to operate the WFGM 

process at a pH near the IEP of sized fiberglass (usually a neutral pH, see Figure 7 or Figure 3 for the sized glass curve). 

Part II: ZETA POTENTIAL MEASUREMENT 

There are four types of techniques that can be used to measure zeta potential: microelectrophoresis, streaming potential, 

electro-osmosis, and sedimentation potential. Although the experimental setup, driving force, and calculation methods may 

vary widely, these four methods are all based on a same principle: a relative motion (Figure 8) between the charged surface 

and the part of electrical double layer that is sheared off from the charged surface. A brief description about each method is 

given as follows and is also summarized in Table 1. 



Table 1 

METHODS FOR ZETA POTENTIAL MEASUREMENT 

Driving 

Stationary Moving Sample 

Methods Force Potential Phase Phase Preparation 

Microelectrophoresis electrical field applied liquid solid dispersed 

particles 

Electro-Osmosis electrical field applied solid liquid porous plug 

Streaming Potential pressure induced solid liquid porous plug 

Sedimentation Potential gravity induced liquid solid dispersed 

particles 

1. Microelectrophoresis - An applied electrical potential causes charged particles to move through a continuous liquid phase. 

Mobility (migration velocity) of the charged particles is measured and zeta potential is calculated based on its relation to the 

mobility. 

2. Streaming Potential - An applied pressure head forces a continuous liquid phase to flow past a charged solid phase 

(porous plug) and a streaming potential is created due to the motion of liquid phase in relation to the charged solid. Streaming 

potential is measured and zeta potential is calculated based on its relation to the streaming potential. 

3. Electro-osmosis - An applied electrical potential causes a continuous liquid phase to flow past a charged solid phase 

(porous plug). The volumetric flow rate is measured and zeta potential is calculated based on its relation to the capillary flow 

rate. 

4. Sedimentation Potential - Gravitational force causes charged particles to settle and a sedimentation potential is created 

due to the motion of charged particles in relation to the stationary liquid phase. The sedimentation potential is measured and 

zeta potential is calculated based on its relation to the sedimentation potential. 

Lab Zeta Potential Measurement 

Both microelectrophoresis and streaming potential methods have been successfully used in lab zeta potential measurement, 

and each has some advantages and disadvantages. Microelectrophoresis measures charged particles, which are first 

suspended in a liquid, then filled into a flat rectangular measuring cell. A pair of electrodes are connected to the opposite 

ends of the sample cell. Under the influence of an applied electrical field, the suspended particles will move toward an 

appropriate electrode. The particle mobility (migration velocity) is measured, then, the zeta potential can be calculated 

(Equation 7). 

The method is reliable because the fundamentals are well understood and theoretical calculation is well developed. 

Practically, it is a very good method for the characterization of particle/powder materials. However, it is not convenient for 

characterization of fiber or fabric materials. For example, glass fibers have to be grounded or crushed before it can be 

measured. When sized fibers are grounded to particles, the exposed new surface (bare surface) may be quite different from 

the sized surface. 

= U / E [7] 

= 4 E s + 2 s /R)/ P [8] 

where 

= zeta potential 

U = mobility (migration velocity) 

= kinematics viscosity of the fluid 

E = applied electrical field strength 

= dielectric constant of the fluid 

P = pressure head 

E s = streaming potential 



= specific conductivity of the fluid 

s = specific conductivity of the surface 

R = radius of capillary 

Streaming potential method directly measures fiber (or fabric) surface, which are packed into a cylindrical tube. A pump 

(pressure head) forces an electrolyte solution to flow through the fiberglass pack (porous plug). Consequently, the flow 

induces a streaming potential across the sample pack. The streaming potential is measured with a pair of electrodes placed at 

the opposite ends of fiberglass pack, recorded with a potentiometer, and used to calculate the zeta potential (Equation 8). It is 

certainly an advantage that the zeta potential of fiber surface (bare or sized) can be directly measured. Streaming potential 

method, however, also has some disadvantages. For instance, the reproducibility of fiberglass pack is a concern, and a more 

vigorous theoretical correction for the effect of surface conductivity is needed to improve the accuracy of streaming potential 

method. 

In-Line Zeta Potential Measurement 

In general, there is no in-line version instrument available for the WFGM process at this time. Recently a couple of in-line 

zeta potential measurement instruments have been developed for paper mills. But, they are not applicable for the WFGM 

process, due to their limits either in measurable slurry consistencies or in manageable fiber lengths, etc. 

References 

1. Dong, D., et al, Tappi 79(7), 191(1996). 

2. Rosen M. J., "Surfactants and Interfacial Phenomena," 2nd edition, John Wiley & Son, New York, 1989. 

3. Adamson, A. W., "Physical Chemistry of Surface (4th edition)," Wiley-Interscience, New York, 1982. 

4. Hiemenz P. C., "Principle of Colloid and Surface Chemistry," Marcel Dekker, New York, 1986. 

5. Shaw D. J., "Introduction to Colloid and Surface Science (3rd edition)," Butterworths, London, 1980. 

6. Matijevic, E. Et al, J. Physical Chemistry, 65, 826 (1961). 

7. James R. O. and Healy T. W., J. Colloid and Interface Science, 40(1), 53 (1972). 

8. Chapman D. L., Philos. Mag., 25, 475 (1913). 

9. Gouy G. J., J. Phys, 9, 457(1910). 

10. Gouy G. J., Ann. Phys., 7, 129 (1917). 

11. Stern O. Z., Electrochemistry, 30, 508 (1924). 

Acknowledgments 

The author would like to thank Dr. Kathryn Brandenburg, leader of the Composites Engineered Fiber Structures COE at the 

Owens Corning Science and Technology Center, Granville, OH, for supporting the preparation and publication of this work. 

—INJ 




Monitoring Of Dynamic Forces 


Applications Of On-Line Monitoring Of Dynamic Forces 

Experienced By Needles During Formation Of Needled 

Fabrics 

By Abdelfattah M. Seyam, Nonwovens Cooperative Research Center, College of Textiles, North Carolina 

State University, Raleigh, North Carolina, USA 

Abstract 

The significance of a recently developed system that measures dynamic forces experienced by individual 

needles during formation of needlepunched fabrics is demonstrated. The system design, coupled with a 

new signal analysis technique allows measurement of peak penetration and stripping forces as well as the 

penetration and stripping energies due to needle/fiberweb interaction. Systematic experimental 

investigations were conducted to determine the critical locations in the needle board where needles 

experience the highest forces, and correlate needle force parameters to fabric performance. 

The research results, supported by statistical analysis, show there is a strong relationship between needle 

penetration energy and fabric properties. Additionally, the needling density significantly impacts the 

location of maximum penetration forces. 

Introduction 

The needlepunching industry was once considered a "waste products" industry, but has now successfully 

established itself in numerous first quality markets. Recently, Smith [10] listed eighteen markets of 

needlepunched products. These include: automotive (headliner, door trim, etc.), filtration, furniture and 

bedding, geotextiles, roofing, aerospace (shuttle tiles, brake pads, etc.), agriculture, advanced composites, 

industrial (belting, roller linings, etc.), insulators, marine, medical (blood filters, bandages, etc.), paper 

making felts, protective clothing, sports felts (floor covering, tennis ball covers, etc.), synthetic 

leather/shoes, wall coverings, and miscellaneous (carpet underlay, car wash brushes, oil sorbents, office 

products, etc.). 

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The success of the industry can be attributed to low manufacturing cost and the flexibility of the 

needlepunching technology to tailor products to meet a variety of end use requirements. The increasing 

demand for needled fabrics prompted machine manufacturers to construct high-speed/high performance 

needle looms. Today's needle looms are capable of running at speeds of up to 3,000 strokes/min. with 

working width of up to 15 meters. A parallel effort has been pursued by needle manufacturers to produce 

high performance needles. Needles are engineered with numerous design parameters in attempts to 

obtain needled fabrics with desired properties to meet end use requirements. These parameters include: 

number of barbs, barb spacing, needle gauge, kick-up size and needle shape. 

Historically, William Bywater of Leeds, England [1] manufactured the first commercial needle machine 

in the late 1800's; however, scientific research was not published until the 1960's. The published research 

has targeted three areas: 

● 

● 

● 

Experimental work to study the influence of processing and fiber parameters on needled fabrics 

properties, 

Approaches to model the tensile behavior of needled fabrics, and 

Developing devices to measure forces acting on needles. 

Recently Sarin, Meng and Seyam [6] published a review of previous work on needle force 

measurements. They found that the previous work was either performed statically using multiple needles 

or dynamically at low speed using both single and multiple needles. These techniques are incapable of 

providing the accurate information important to needle manufacturers, machine producers and fabric 

producers. Demand exists for a system capable of measuring needle forces during high-speed needling. 

Seyam, Meng and Mohamed have developed recently such system [7] that is briefly described later in 

this paper. 

While the previous studies provided basic understanding, the results and conclusions of such studies are 

valid only for the experimental range used. Moreover, the studies were conducted using small machines 

producing narrow fabrics at low needling speed. The applicability of such findings to an industry that 

uses today's high-speed needle looms producing wide fabrics is questionable. Additionally, in a research 

environment, an experiment is often run for extremely short time. In industry, however, the continuous 

processing of fabrics causes needle wear and, as a result, fabric properties may be significantly deviate 

from the desired levels. 

There is relatively limited literature regarding the modeling of fabric performance; only two publications 

have been identified. The first was published by Hearle and Sultan [2] showing an approach to 

theoretical understanding of tensile behavior of needled fabrics. The other publication, by Ji [3], 

developed a model to predict the entire load-extension behavior of needled fabrics. While his work is an 

improvement, the theoretical model and experimental results did not significantly agree. This is due to 

the assumptions used to develop the model in order to facilitate the prediction. Needled fabrics are 

complex structures that are very difficult to model. It would be extremely beneficial to the industry to 

develop an on-line technique that is capable of monitoring and controlling of fabric properties while the 



fabrics are being produced. Our research team at the Nonwoven Cooperative Research Center undertook 

research efforts to accomplish this goal, developing a new system that measures dynamic forces 

experienced by individual needles during formation of needlepunched fabrics. 

Needle Force Measurement System 

Figure 1 shows the components of the needle force measurement system developed by Seyam, Meng and 

Mohamed [7]. The force data could be collected from nine different instrumented needles located in the 

machine and cross machine directions (Figure 2). 

The NCRC needle force measurement system consists of force transducers in washer form, signal 

conditioner, data acquisition hardware and software, and data analysis software. These, along with 

possible applications of the system are fully explained in previous publications [5-9]. 

Figure 1 

FORCE MEASUREMENT SYSTEM 

Figure 2 

LOCATIONS OF THE FIVE-INSTRUMENTED 

NEEDLES IN THE NEEDLE BOARD 

Signal Analysis 

Using signal analysis, we developed a technique to extract useful information from force data collected 

on-line [8]. The signal analysis procedure involves data filtration using low frequency pass filter in order 

to filter out vibration. Then the filtered data is processed to subtract the forces exerted on the needles due 

to inertia. The remaining forces are those due to needle/fiberweb interactions. From this data, needle 

penetration and stripping forces as well as energies can be deduced. Figure 3 shows the superimposition 

of the filtered data for total forces (solid line) and the inertia forces (dotted line) for several needling 

cycles. The solid line ABCDEF represents the total force experienced by an instrumented needle, while 

the dotted line ABCD'F represents the inertia forces. The solid portion CD represents the data of the 

penetrating forces experienced by the needle during the downward movement of the needle board. Point 

D is the peak penetration force corresponding to the highest pressure the needle experiences from the 

fiberweb. During the portion DE, the pressure on the needle is reduced due to the upward movement of 

the needle board. The pressure reaches zero at the point where DE intercepts the dotted line. Beyond the 



interception point, the needle is subjected to stripping forces as a result of its withdrawal from the 

fiberweb. 

Figure 3 

SUPERIMPOSITION OF TOTAL AND 

INERTIA FORCES IN TIME DOMAIN 

Figure 4 

NET NEEDLE FORCES DUE TO FIBERWEB 

RESISTANCE 

From Figure 3 one can notice that the total forces (solid line) and the inertia forces (dotted line) are 

identical during half cycle or at least during quarter cycle AB. This feature allows modeling of the whole 

inertia cycle ABC'D'F as a sinusoidal function. Subtraction of inertia forces from total forces gives the 

net forces that the needle experienced due to penetration of and withdrawal from the fiberweb (Figure 4). 

From the net force data of Figure 4 and the time-displacement data of the needle board, penetration and 

stripping energies can be determined. 

Applications of the Needle Force Measurement System 

In this section, the experimental procedures and results are given for two applications of the system: 

Determination of the critical locations in the needle board at which needles experience the highest forces, 

and correlation of needle force parameters with fabric performance. For both applications, the force data 

were acquired from five instrumented needles (marked 1 through 5, Figure 2). The data was recorded 

simultaneously for each needle at a rate of 1,000 observations/sec. 

Correlation Between Force Parameters and Fabric Performance 

Experimental 

For this part of the study a total of sixteen needled fabrics were produced representing a full experimental 

design (4 levels of weight x 4 levels of needling density). For each fabric, three sets (replicates) of force 

data were collected at different times. For each set, force data of 150 needling cycles per instrumented 

needle were collected by the force measurement system. The fabrics were comprised of polypropylene 

fibers produced at 76.2 mm fiber length and 10 denier/filament. Fabrics were produced using carding and 

cross-lapping prior to needling. More details are published elsewhere by Kim and Seyam [4]. The 



properties (responses) selected for this study are tensile and tear resistance. Statistical Analysis System 

(SAS) was used to develop regression equations correlating needle penetration energy to needled fabric 

performance. 

Calculation of Penetration Energy 

The penetration energy (J/cm 2 ) was obtained by integrating the area under the curve of net needle force 

due to fiberweb resistance (Figure 4) combined with needle board displacement and the needling density. 

For each fabric the data was averaged over 2,250 needling cycles (3 replicates x 5 needles x 150 cycles) 

and used as an estimate for the energy expended to bond the fabric. 

Figure 5 

BREAKING ENERGY VS. PENETRATION 

ENERGY 

Figure 6 

PREDICTED TEAR STRENGTH VS. 

PENETRATION ENERGY 

Results and Discussion 

For each of the experimental run, the force data was fed into a computer, which calculated the 

penetration energy. Figures 5 and 6 show the predicted relationships between needling energies and 

needled fabric performance as well as the correlation for each with the experimental data. The symbols 

of the predictive equations shown in Figures 5 and 6 are defined as follows: 

BE = Tensile Breaking Energy, J 

PE = Needling Penetration Energy, J/cm 2 

TS = Tear Resistance, N 

W = Needled Fabric Basis Weight, g/m 2 

Figure 5 depicts the relationship between needling energy and the energy required breaking the fabrics in 

tensile mode. The experimental data and the predictive equation of Figure 5 indicate that the relationship 



between penetration energy and breaking energy is linear with high correlation coefficient (R2=0.9018). 

Figure 6 shows the predictive equation of the needling energy and the tear resistance of the needled 

fabrics. Unlike the breaking energy, tear resistance is impacted significantly by fabric basis weight. For a 

given weight, increasing the penetration energy (needling density) reduces the tear resistance. This can 

be explained by the decrease in the degree of fiber mobility with the increase in the penetration energy 

(due to increase in fiber interlocking with needling density). The high degree of fiber interlocking hinders 

the fiber movement to the delta zone during tear tests. Consequently, fewer fibers move to delta zone to 

share the load from the tear stresses. The high correlation coefficients (R2 = 0.9754) of the predictive 

equation of Figure 6 indicates that the needling energies and fabric weight are highly correlated to 

needled fabric tear resistance. It must be noted that this strong linear correlation should only be applied in 

the range over which the data was measured. Significant non-linearity is expected at very low needle 

densities. 

Figure 7 

PEAK PENETRATION FORCE IN TERMS OF 

NEEDLE LOCATION AND NEEDLING 

DENSITY. FABRIC WEIGHT = 260 G/M 2 , 

NUMBER OF BARBS = 9 

Figure 8 

PEAK PENETRATION FORCE IN TERMS 

OF NEEDLE LOCATION AND NEEDLING 

DENSITY. FABRIC WEIGHT= 650 G/M 2 , 


Significance 

The high correlation between fabric properties and penetration energies means that this technique can be 

used to predict and control the fabric properties while the fabrics are being produced. A computer 

algorithm can be developed for these on-line estimates through the predictive equations. 



Determination of the Critical Locations In The Needle 

Board At Which Needles Experience The Highest 

Force 

Experimental 

To determine the locations where needles experience the 

highest penetration forces, a series of runs were performed 

on 60 cm wide Dilo loom using carded and cross-lapped 

fiberwebs. The fiber webs were produced from 

polypropylene fibers with 76.2 mm fiber length and 10 

denier/filament. A full experimental design (4 levels of 

weight x 4 levels of needling density x 5 levels of needle 

location) was conducted. Each run was replicated three 

times. For each run, force data of 150 needling cycles per 

Figure 9 

LOCUS OF THE MAXIMUM PEAK 

PENETRATION FORCE 

instrumented needle were collected by the force measurement system. The key parameter of interest here 

is the peak penetration force due to fiberweb resistance that is developed after a certain number of 

strokes (cycles of Figure 4). Again, SAS was used to develop regression equations relating peak needle 

penetration force to needle location, fabric weight and needling density. 


Figures 7 and 8 show the predicted peak penetration forces as influenced by needling density, needle 

location and fabric weight. In these figures, the needle location represents the distance from the first row 

in the needle board at the feed side. Therefore, location = 0 cm indicates the first needle row where the 

fiberweb starts to receive needling. At location = 18 cm, the fiberweb received the target needling density 

(last needle row). 

It can be noticed from Figures 7 and 8 that the peak force increases with location up to a certain 

maximum value after which the peak penetration force decreases. Additionally, the maximum peak 

penetration force is dependent on the level of needling density. The location of the maximum moves 

toward the feed side as the needling density increases and toward the delivery side as the needling 

density decreases. The results indicate there may be several phenomena at play; their relative force 

contributions being dependent on the level of fiberweb integrity. Details of these force contributions are 

not yet understood but are postulated to include the following effects: 

● 

● 

● 

At locations near the feed side the fiberweb is bulky, which leads to frictional forces for the 

needles penetrating due to long contact length between fiberweb and needles. Additionally, the 

number of fibers caught by needle barbs at the feed side is higher compared to the delivery side. 

As bonding progresses, fibers become more entangled and the fiberweb is more consolidated. 

Thus, the fibers are more trapped in the fiberweb, resulting in an increased force contribution of a 

fiber caught by a needle. 

As the web advances to the delivery side, it receives more punches that cause fiber breakage. 

Consequently, the broken fibers contribute less to the needle forces. 

file:///D|/WWW/inda/subscrip/inj99_2/seyam2.html (7 of 9) [6/25/2003 10:54:01 AM]


● 

Additionally, as the web advances to the delivery side and the web is more consolidated, each 

needle tends to engage fewer fibers. 

Additional results similar to these of Figures 7 and 8 using other types of needles are published 

elsewhere [5]. 

Figure 9 shows a generalized version of the needling density distribution that the web receives at 

different locations of the needle board. The four straight lines represent the needling density distribution 

of different target needling densities (50, 70, 90 and 110 punches/cm 2 ). Based on the above discussion on 

the effect of the needling density on the location of the maximum peak force, one would assume that the 

maximum would take place at a certain critical needling density. This means that a line as shown in 

Figure 9 can represent the locus of the maximum. The intercepts of this line with the four lines 

representing the needling density distribution determine the location of the maximum peak penetration 

force. Our results show however, that this locus is not necessarily a straight line, in fact the locus could 

assume a general line or curve. Irrespective of the exact shape of the critical line, the reason why the 

location of the maximum peak force varies with needling density is clear. The maximum peak force is 

strongly dependent on the total number of punches encountered by the web as it progresses through the 

needle loom. 

Significance of Locating The Position Of Maximum Peak Force 

Needle Rotation Technique 

To maximize needle utilization, fabric producers developed methods to rotate the needles in the needle 

board after a given number of needling cycles. This is done since the needles are subjected to different 

forces, and hence different wear levels, depending on their location in the needle board. The rotation 

supposes to equalize the needle wear. Each needled fabric producer developed different techniques of 

needle rotation based on experience. Thus, the needle rotation is considered as an art rather than science. 

To base this on science, needles should be rotated based on the force distribution of Figures 7 and 8. 

Needles in the rows where the force is high should be moved to locations of low forces. 

The force measurement system, therefore, could rationalize the needle rotation process. 

Needle Design 

Another significant benefit of the determination of the needle force distribution is needle design. Needle 

manufacturers can make use of the results to design needles to withstand the high stress positions and 

thereby avoid excessive needle breakage during fabric formation. Alternatively, this understanding may 

allow the strongest (and presumably most expensive) needles to be mounted in positions of highest 

stress. 

The industry benefit would be production of high quality needled fabrics at high efficiency. 

Conclusion 



Our research findings showed that the force measurement device coupled with signal analysis have 

significant benefits to needled fabric producers as well as needle manufacturers. The high correlation 

found between needle force parameters and fabric properties can be used to on-line monitor the needled 

fabric properties to ensure the produced fabrics are within the specified requirements. The location of the 

maximum needle forces is essential for fabric producers to rationalize the needle rotation technique in 

order to maximize the needle utilization. Additionally, needle producers can make use of the information 

in designing high performance needles. 

Acknowledgment 

This work was supported by the Nonwovens Cooperative Research Center, which is funded by the 

National Science Foundation, the State of North Carolina, and Industry Members. 

Reference 

1. Foster, J.H., "Needlepunching - Past, Present and Future," INDA-TEC '88 209 (1988) 

2. Hearle, J.W.S., and Sultan, M.A.I., "Study of Needled Fabrics, Part V: The approach to theoretical 

understanding," J. Text. Inst., 59, 183 (1968). 

3. Ji, Y., Tensile Properties of Needlepunched Nonwoven Fabrics, Ph. D. Thesis, North Carolina State 

University, 1992. 

4. Kim, H. and Seyam, A.M., Needle Force Parameters/Needled Fabric Performance Relationships, 

Proceedings of the INDA International Needlepunch Conference, Charlotte, NC, October, 1998. 

5. Kim, H., Study of Needlepunching Process and Products, Ph. D. Thesis, North Carolina State 


6. Sarin, S., Meng, J., and Seyam, A. M., "Mechanics of Needlepunching Process and Products, Part I: 

Critical Review of Previous Work on Forces Experienced by Needles during Needling of Nonwoven 

Fabrics," International Nonwovens J., 6, 32 (1994). 

7. Seyam, A.M., Meng, J., and Mohamed, A., "Mechanics of Needlepunching Process and Products, Part 

II: An On-Line Device to Measure the Punching Forces Experienced by Individual Needles," 

International Nonwovens J., 7, 31 (1995). 

8. Seyam, A.M., Mohamed, A.S., and Kim, H., "Signal Analysis of Dynamic Forces Experienced by 

Individual Needles at High Speed Needlepunching," Text. Res. J., 68, 296 (1998). 

9. Seyam, A.M., and Sarin, S., "Effect of Needle Position and Orientation on Forces Experienced by 

Individual Needle during Needle Punching," Text. Res. J., 67, 772 (1997) 

10. Smith, W.C., Markets for Technical Needled Fabrics, Proceedings of the INDA's International 

Needlepunch Conference, Charlotte, NC, October, 1998. - INJ 



Need Reprints? 




Applications Of On-Line Monitoring Of Dynamic Forces 

Experienced By Needles During Formation Of Needled 

Fabrics 

By Abdelfattah M. Seyam, Nonwovens Cooperative Research Center, College of Textiles, North Carolina 

State University, Raleigh, North Carolina, USA 

Abstract 

The significance of a recently developed system that measures dynamic forces experienced by individual 

needles during formation of needlepunched fabrics is demonstrated. The system design, coupled with a 

new signal analysis technique allows measurement of peak penetration and stripping forces as well as the 

penetration and stripping energies due to needle/fiberweb interaction. Systematic experimental 

investigations were conducted to determine the critical locations in the needle board where needles 

experience the highest forces, and correlate needle force parameters to fabric performance. 

The research results, supported by statistical analysis, show there is a strong relationship between needle 

penetration energy and fabric properties. Additionally, the needling density significantly impacts the 

location of maximum penetration forces. 

Introduction 

The needlepunching industry was once considered a "waste products" industry, but has now successfully 

established itself in numerous first quality markets. Recently, Smith [10] listed eighteen markets of 

needlepunched products. These include: automotive (headliner, door trim, etc.), filtration, furniture and 

bedding, geotextiles, roofing, aerospace (shuttle tiles, brake pads, etc.), agriculture, advanced composites, 

industrial (belting, roller linings, etc.), insulators, marine, medical (blood filters, bandages, etc.), paper 

making felts, protective clothing, sports felts (floor covering, tennis ball covers, etc.), synthetic 

leather/shoes, wall coverings, and miscellaneous (carpet underlay, car wash brushes, oil sorbents, office 

products, etc.). 



The success of the industry can be attributed to low manufacturing cost and the flexibility of the 

needlepunching technology to tailor products to meet a variety of end use requirements. The increasing 

demand for needled fabrics prompted machine manufacturers to construct high-speed/high performance 

needle looms. Today's needle looms are capable of running at speeds of up to 3,000 strokes/min. with 

working width of up to 15 meters. A parallel effort has been pursued by needle manufacturers to produce 

high performance needles. Needles are engineered with numerous design parameters in attempts to 

obtain needled fabrics with desired properties to meet end use requirements. These parameters include: 

number of barbs, barb spacing, needle gauge, kick-up size and needle shape. 

Historically, William Bywater of Leeds, England [1] manufactured the first commercial needle machine 

in the late 1800's; however, scientific research was not published until the 1960's. The published research 

has targeted three areas: 

● 

● 

● 

Experimental work to study the influence of processing and fiber parameters on needled fabrics 

properties, 

Approaches to model the tensile behavior of needled fabrics, and 

Developing devices to measure forces acting on needles. 

Recently Sarin, Meng and Seyam [6] published a review of previous work on needle force 

measurements. They found that the previous work was either performed statically using multiple needles 

or dynamically at low speed using both single and multiple needles. These techniques are incapable of 

providing the accurate information important to needle manufacturers, machine producers and fabric 

producers. Demand exists for a system capable of measuring needle forces during high-speed needling. 

Seyam, Meng and Mohamed have developed recently such system [7] that is briefly described later in 

this paper. 

While the previous studies provided basic understanding, the results and conclusions of such studies are 

valid only for the experimental range used. Moreover, the studies were conducted using small machines 

producing narrow fabrics at low needling speed. The applicability of such findings to an industry that 

uses today's high-speed needle looms producing wide fabrics is questionable. Additionally, in a research 

environment, an experiment is often run for extremely short time. In industry, however, the continuous 

processing of fabrics causes needle wear and, as a result, fabric properties may be significantly deviate 

from the desired levels. 

There is relatively limited literature regarding the modeling of fabric performance; only two publications 

have been identified. The first was published by Hearle and Sultan [2] showing an approach to 

theoretical understanding of tensile behavior of needled fabrics. The other publication, by Ji [3], 

developed a model to predict the entire load-extension behavior of needled fabrics. While his work is an 

improvement, the theoretical model and experimental results did not significantly agree. This is due to 

the assumptions used to develop the model in order to facilitate the prediction. Needled fabrics are 

complex structures that are very difficult to model. It would be extremely beneficial to the industry to 

develop an on-line technique that is capable of monitoring and controlling of fabric properties while the 



fabrics are being produced. Our research team at the Nonwoven Cooperative Research Center undertook 

research efforts to accomplish this goal, developing a new system that measures dynamic forces 

experienced by individual needles during formation of needlepunched fabrics. 

Needle Force Measurement System 

Figure 1 shows the components of the needle force measurement system developed by Seyam, Meng and 

Mohamed [7]. The force data could be collected from nine different instrumented needles located in the 

machine and cross machine directions (Figure 2). 

The NCRC needle force measurement system consists of force transducers in washer form, signal 

conditioner, data acquisition hardware and software, and data analysis software. These, along with 

possible applications of the system are fully explained in previous publications [5-9]. 

Figure 1 

FORCE MEASUREMENT SYSTEM 

Figure 2 

LOCATIONS OF THE FIVE-INSTRUMENTED 

NEEDLES IN THE NEEDLE BOARD 

Signal Analysis 

Using signal analysis, we developed a technique to extract useful information from force data collected 

on-line [8]. The signal analysis procedure involves data filtration using low frequency pass filter in order 

to filter out vibration. Then the filtered data is processed to subtract the forces exerted on the needles due 

to inertia. The remaining forces are those due to needle/fiberweb interactions. From this data, needle 

penetration and stripping forces as well as energies can be deduced. Figure 3 shows the superimposition 

of the filtered data for total forces (solid line) and the inertia forces (dotted line) for several needling 

cycles. The solid line ABCDEF represents the total force experienced by an instrumented needle, while 

the dotted line ABCD'F represents the inertia forces. The solid portion CD represents the data of the 

penetrating forces experienced by the needle during the downward movement of the needle board. Point 

D is the peak penetration force corresponding to the highest pressure the needle experiences from the 

fiberweb. During the portion DE, the pressure on the needle is reduced due to the upward movement of 

the needle board. The pressure reaches zero at the point where DE intercepts the dotted line. Beyond the 



interception point, the needle is subjected to stripping forces as a result of its withdrawal from the 

fiberweb. 

Figure 3 

SUPERIMPOSITION OF TOTAL AND 

INERTIA FORCES IN TIME DOMAIN 

Figure 4 

NET NEEDLE FORCES DUE TO FIBERWEB 

RESISTANCE 

From Figure 3 one can notice that the total forces (solid line) and the inertia forces (dotted line) are 

identical during half cycle or at least during quarter cycle AB. This feature allows modeling of the whole 

inertia cycle ABC'D'F as a sinusoidal function. Subtraction of inertia forces from total forces gives the 

net forces that the needle experienced due to penetration of and withdrawal from the fiberweb (Figure 4). 

From the net force data of Figure 4 and the time-displacement data of the needle board, penetration and 

stripping energies can be determined. 

Applications of the Needle Force Measurement System 

In this section, the experimental procedures and results are given for two applications of the system: 

Determination of the critical locations in the needle board at which needles experience the highest forces, 

and correlation of needle force parameters with fabric performance. For both applications, the force data 

were acquired from five instrumented needles (marked 1 through 5, Figure 2). The data was recorded 

simultaneously for each needle at a rate of 1,000 observations/sec. 

Correlation Between Force Parameters and Fabric Performance 

Experimental 

For this part of the study a total of sixteen needled fabrics were produced representing a full experimental 

design (4 levels of weight x 4 levels of needling density). For each fabric, three sets (replicates) of force 

data were collected at different times. For each set, force data of 150 needling cycles per instrumented 

needle were collected by the force measurement system. The fabrics were comprised of polypropylene 

fibers produced at 76.2 mm fiber length and 10 denier/filament. Fabrics were produced using carding and 

cross-lapping prior to needling. More details are published elsewhere by Kim and Seyam [4]. The 



properties (responses) selected for this study are tensile and tear resistance. Statistical Analysis System 

(SAS) was used to develop regression equations correlating needle penetration energy to needled fabric 

performance. 

Calculation of Penetration Energy 

The penetration energy (J/cm 2 ) was obtained by integrating the area under the curve of net needle force 

due to fiberweb resistance (Figure 4) combined with needle board displacement and the needling density. 

For each fabric the data was averaged over 2,250 needling cycles (3 replicates x 5 needles x 150 cycles) 

and used as an estimate for the energy expended to bond the fabric. 

Figure 5 

BREAKING ENERGY VS. PENETRATION 

ENERGY 

Figure 6 

PREDICTED TEAR STRENGTH VS. 

PENETRATION ENERGY 


For each of the experimental run, the force data was fed into a computer, which calculated the 

penetration energy. Figures 5 and 6 show the predicted relationships between needling energies and 

needled fabric performance as well as the correlation for each with the experimental data. The symbols 

of the predictive equations shown in Figures 5 and 6 are defined as follows: 

BE = Tensile Breaking Energy, J 

PE = Needling Penetration Energy, J/cm 2 

TS = Tear Resistance, N 

W = Needled Fabric Basis Weight, g/m 2 

Figure 5 depicts the relationship between needling energy and the energy required breaking the fabrics in 

tensile mode. The experimental data and the predictive equation of Figure 5 indicate that the relationship 



between penetration energy and breaking energy is linear with high correlation coefficient (R2=0.9018). 

Figure 6 shows the predictive equation of the needling energy and the tear resistance of the needled 

fabrics. Unlike the breaking energy, tear resistance is impacted significantly by fabric basis weight. For a 

given weight, increasing the penetration energy (needling density) reduces the tear resistance. This can 

be explained by the decrease in the degree of fiber mobility with the increase in the penetration energy 

(due to increase in fiber interlocking with needling density). The high degree of fiber interlocking hinders 

the fiber movement to the delta zone during tear tests. Consequently, fewer fibers move to delta zone to 

share the load from the tear stresses. The high correlation coefficients (R2 = 0.9754) of the predictive 

equation of Figure 6 indicates that the needling energies and fabric weight are highly correlated to 

needled fabric tear resistance. It must be noted that this strong linear correlation should only be applied in 

the range over which the data was measured. Significant non-linearity is expected at very low needle 

densities. 

Figure 7 

PEAK PENETRATION FORCE IN TERMS OF 

NEEDLE LOCATION AND NEEDLING 

DENSITY. FABRIC WEIGHT = 260 G/M 2 , 


Figure 8 

PEAK PENETRATION FORCE IN TERMS 

OF NEEDLE LOCATION AND NEEDLING 

DENSITY. FABRIC WEIGHT= 650 G/M 2 , 


Significance 

The high correlation between fabric properties and penetration energies means that this technique can be 

used to predict and control the fabric properties while the fabrics are being produced. A computer 

algorithm can be developed for these on-line estimates through the predictive equations. 



Determination of the Critical Locations In The Needle 

Board At Which Needles Experience The Highest 

Force 

Experimental 

To determine the locations where needles experience the 

highest penetration forces, a series of runs were performed 

on 60 cm wide Dilo loom using carded and cross-lapped 

fiberwebs. The fiber webs were produced from 

polypropylene fibers with 76.2 mm fiber length and 10 

denier/filament. A full experimental design (4 levels of 

weight x 4 levels of needling density x 5 levels of needle 

location) was conducted. Each run was replicated three 

times. For each run, force data of 150 needling cycles per 

Figure 9 

LOCUS OF THE MAXIMUM PEAK 

PENETRATION FORCE 

instrumented needle were collected by the force measurement system. The key parameter of interest here 

is the peak penetration force due to fiberweb resistance that is developed after a certain number of 

strokes (cycles of Figure 4). Again, SAS was used to develop regression equations relating peak needle 

penetration force to needle location, fabric weight and needling density. 


Figures 7 and 8 show the predicted peak penetration forces as influenced by needling density, needle 

location and fabric weight. In these figures, the needle location represents the distance from the first row 

in the needle board at the feed side. Therefore, location = 0 cm indicates the first needle row where the 

fiberweb starts to receive needling. At location = 18 cm, the fiberweb received the target needling density 

(last needle row). 

It can be noticed from Figures 7 and 8 that the peak force increases with location up to a certain 

maximum value after which the peak penetration force decreases. Additionally, the maximum peak 

penetration force is dependent on the level of needling density. The location of the maximum moves 

toward the feed side as the needling density increases and toward the delivery side as the needling 

density decreases. The results indicate there may be several phenomena at play; their relative force 

contributions being dependent on the level of fiberweb integrity. Details of these force contributions are 

not yet understood but are postulated to include the following effects: 

● 

● 

● 

At locations near the feed side the fiberweb is bulky, which leads to frictional forces for the 

needles penetrating due to long contact length between fiberweb and needles. Additionally, the 

number of fibers caught by needle barbs at the feed side is higher compared to the delivery side. 

As bonding progresses, fibers become more entangled and the fiberweb is more consolidated. 

Thus, the fibers are more trapped in the fiberweb, resulting in an increased force contribution of a 

fiber caught by a needle. 

As the web advances to the delivery side, it receives more punches that cause fiber breakage. 

Consequently, the broken fibers contribute less to the needle forces. 



● 

Additionally, as the web advances to the delivery side and the web is more consolidated, each 

needle tends to engage fewer fibers. 

Additional results similar to these of Figures 7 and 8 using other types of needles are published 

elsewhere [5]. 

Figure 9 shows a generalized version of the needling density distribution that the web receives at 

different locations of the needle board. The four straight lines represent the needling density distribution 

of different target needling densities (50, 70, 90 and 110 punches/cm 2 ). Based on the above discussion on 

the effect of the needling density on the location of the maximum peak force, one would assume that the 

maximum would take place at a certain critical needling density. This means that a line as shown in 

Figure 9 can represent the locus of the maximum. The intercepts of this line with the four lines 

representing the needling density distribution determine the location of the maximum peak penetration 

force. Our results show however, that this locus is not necessarily a straight line, in fact the locus could 

assume a general line or curve. Irrespective of the exact shape of the critical line, the reason why the 

location of the maximum peak force varies with needling density is clear. The maximum peak force is 

strongly dependent on the total number of punches encountered by the web as it progresses through the 

needle loom. 

Significance of Locating The Position Of Maximum Peak Force 

Needle Rotation Technique 

To maximize needle utilization, fabric producers developed methods to rotate the needles in the needle 

board after a given number of needling cycles. This is done since the needles are subjected to different 

forces, and hence different wear levels, depending on their location in the needle board. The rotation 

supposes to equalize the needle wear. Each needled fabric producer developed different techniques of 

needle rotation based on experience. Thus, the needle rotation is considered as an art rather than science. 

To base this on science, needles should be rotated based on the force distribution of Figures 7 and 8. 

Needles in the rows where the force is high should be moved to locations of low forces. 

The force measurement system, therefore, could rationalize the needle rotation process. 

Needle Design 

Another significant benefit of the determination of the needle force distribution is needle design. Needle 

manufacturers can make use of the results to design needles to withstand the high stress positions and 

thereby avoid excessive needle breakage during fabric formation. Alternatively, this understanding may 

allow the strongest (and presumably most expensive) needles to be mounted in positions of highest 

stress. 

The industry benefit would be production of high quality needled fabrics at high efficiency. 

Conclusion 



Our research findings showed that the force measurement device coupled with signal analysis have 

significant benefits to needled fabric producers as well as needle manufacturers. The high correlation 

found between needle force parameters and fabric properties can be used to on-line monitor the needled 

fabric properties to ensure the produced fabrics are within the specified requirements. The location of the 

maximum needle forces is essential for fabric producers to rationalize the needle rotation technique in 

order to maximize the needle utilization. Additionally, needle producers can make use of the information 

in designing high performance needles. 

Acknowledgment 

This work was supported by the Nonwovens Cooperative Research Center, which is funded by the 

National Science Foundation, the State of North Carolina, and Industry Members. 

Reference 

1. Foster, J.H., "Needlepunching - Past, Present and Future," INDA-TEC '88 209 (1988) 

2. Hearle, J.W.S., and Sultan, M.A.I., "Study of Needled Fabrics, Part V: The approach to theoretical 

understanding," J. Text. Inst., 59, 183 (1968). 

3. Ji, Y., Tensile Properties of Needlepunched Nonwoven Fabrics, Ph. D. Thesis, North Carolina State 


4. Kim, H. and Seyam, A.M., Needle Force Parameters/Needled Fabric Performance Relationships, 

Proceedings of the INDA International Needlepunch Conference, Charlotte, NC, October, 1998. 

5. Kim, H., Study of Needlepunching Process and Products, Ph. D. Thesis, North Carolina State 


6. Sarin, S., Meng, J., and Seyam, A. M., "Mechanics of Needlepunching Process and Products, Part I: 

Critical Review of Previous Work on Forces Experienced by Needles during Needling of Nonwoven 

Fabrics," International Nonwovens J., 6, 32 (1994). 

7. Seyam, A.M., Meng, J., and Mohamed, A., "Mechanics of Needlepunching Process and Products, Part 

II: An On-Line Device to Measure the Punching Forces Experienced by Individual Needles," 

International Nonwovens J., 7, 31 (1995). 

8. Seyam, A.M., Mohamed, A.S., and Kim, H., "Signal Analysis of Dynamic Forces Experienced by 

Individual Needles at High Speed Needlepunching," Text. Res. J., 68, 296 (1998). 

9. Seyam, A.M., and Sarin, S., "Effect of Needle Position and Orientation on Forces Experienced by 

Individual Needle during Needle Punching," Text. Res. J., 67, 772 (1997) 

10. Smith, W.C., Markets for Technical Needled Fabrics, Proceedings of the INDA's International 

Needlepunch Conference, Charlotte, NC, October, 1998. - INJ 





Development of Thermal Insulation 


Development of Thermal 

Insulation for Textile Wet 

Processing Machinery 

Using Needlepunched Nonwoven Fabrics 

By Randeep S. Grewal, Flynt Fabrics, Inc., and Dr. Pamela Banks-Lee, North Carolina State University 

Abstract 

In textile manufacturing, many fiber manufacturing, dyeing and finishing processes require temperatures in 

the range of 100 o C to 200 o C. A substantial amount of energy is needed to produce the desired temperature, 

and part of this energy is wasted when heat from the process escapes to the environment. Many of the 

processes are batch processes requiring frequent reheating and restarting. Most process equipment is 

constructed from stainless steel, which is a good conductor of heat. In addition to this, because of the cost 

involved in installation and regular maintenance of insulation, many manufacturers do not insulate their 

process equipment. 

The heat and moisture loss to the environment makes the manufacturing facilities environmentally 

uncomfortable for employees. This reduces their productivity and is a health risk. Due to the energy wasted in 

the textile wet processing industry, there is a need to develop suitable insulating materials specifically for 

these applications. For commercial applications, both the cost of the insulating material as well as its 

effectiveness, ease of installation and durability are important. 

Needlepunched fabrics have the potential to meet these demands [1]. Since low density needled felts with 

good heat blocking capacity can be made from durable fibers, they are ideal for heat insulation applications 

[1,2]. This research focuses on identifying suitable fibers and the manufacturing technology which will yield 

the desired results. After testing of prepared samples, the data was analyzed to determine the fabric and fiber 

parameters which influence heat transfer. An economic analysis was also conducted to optimize both cost and 

effectiveness. 

The important factors contributing to the transfer of heat through needlepunched nonwoven fabrics were 

found to be the bulk density of the batt and the surface area of the fibers. Incorporation of low denier fibers 

(meltblown web) in the needlepunched structure led to a significant decrease in the apparent thermal 

conductivity of the batt. A cost analysis of this insulation (incorporating the meltblown web) determined the 

optimum thickness of such an insulation to be 10.1 mm. 

Introduction 

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Heat insulators are defined as those materials or combination of materials with air or evacuated spaces that 

will retard the transfer of heat with reasonable effectiveness under ordinary conditions [3]. Thermal insulation 

is used not only to conserve energy, but also to provide year-round comfort for living and working spaces. 

Needled felts, due to their bulk and internal voids, are inherently good insulators and are widely used for 

insulation purposes [4]. Although a wide array of nonwoven insulation is commercially available for 

wide-ranging applications, their commercial feasibility for application to the textile wet processing industry 

has never been seriously investigated. The textile wet processing industry consumes a large quantity of 

energy for heating water and making steam, which is used in almost all of its processes such as scouring, 

bleaching, dyeing and finishing. The temperature range is approximately 100 o C to 200 o C. As energy costs 

and environmental concerns escalate, this industry has specific needs which must be studied in order to 

develop an appropriate insulation. 

Modes of Heat Transfer in Fibrous Insulations 

When energy is transferred from one body to another by virtue of a temperature difference existing between 

them, it is said that heat is transferred. There are three modes of heat transfer: conduction, radiation and 

convection [3,4]. 

Conduction 

Heat will flow from a high temperature region to a lower temperature region by conduction. In general, the 

particles of matter (molecules, atoms and electrons) in the high-temperature region, being at higher energy 

levels, will transmit some of their energy to the adjacent lower-temperature regions through particle 

interaction. Conduction can be either through gases, liquids or solids. In the case of conduction in gases, the 

interchange of kinetic energy by molecules colliding is the predominant mechanism. In non-metallic solids, 

the primary mechanism is by lattice-vibration wave propagation. Higher temperatures are associated with 

higher molecular energies, and when neighboring molecules collide, as they are constantly doing, a transfer 

of energy from the more energetic to the less energetic molecules occurs [4,5]. 

The heat transfer rate per unit area is proportional to the normal temperature gradient. That is, 

(1.1) 

where q is the heat transfer rate and dT/dx is the temperature gradient in the direction of the heat flow. The 

positive constant k is the thermal conductivity of the material, and the minus sign is inserted so that the 

second principle of thermodynamics will be satisfied, i.e., heat must flow from a body at a higher temperature 

to a body at a lower temperature [6]. 

Convection 

Convective heat transfer may be categorized according to the nature of the flow. It is called forced convection 

when the flow is caused by some external means, such as by a fan, a pump or atmospheric winds. In contrast, 

for free (or natural) convection, the flow is induced by buoyancy in the fluid. These forces arise from density 

variations caused by temperature variations in the fluid. A circulation pattern exists in which the warm fluid 

moves up from the hot surface and cooler fluid moves downwards [7]. Regardless of the particular nature of 

the convective heat transfer mode, the appropriate heat transfer equation is of the form: 



q=h(T s - T o ) (1.2) 

where, 

q : the convective heat flux 

T s : surface temperature, and 

T o : gas temperature. 

h : proportionality constant or convection heat transfer coefficient [7]. 

This expression is known as Newton’s Law of Cooling. This formula encompasses all the effects that 

influence the convection mode. It depends on the conditions in the boundary layer, which are influenced by 

surface geometry, the nature of the fluid motion, and the fluid thermodynamic and transport properties [7,8]. 

Radiation 

In contrast to the mechanisms of conduction and convection, where energy transfer through a material 

medium is involved, heat may also be transferred through regions where a perfect vacuum exists. The 

mechanism in this case is electromagnetic radiation or propagation of a collection of particles termed photons 

or quanta. This is called thermal radiation. Radiation is a surface phenomenon. For radiation propagation in a 

particular medium, its frequency and wavelength l are related by: 

(1.3) 

where c: velocity of light in the medium [4,9]. 

Definition and Basic Equation of Apparent Thermal Conductivity 

Apparent thermal conductivity of a porous material is the overall (sum of all individual conductivity terms) 

conductivity of the material. This value takes into account the conduction due to the solid and gas terms, 

including all the conduction, convection, and radiation values. The apparent thermal conductivity of a 

material can thus be referred to as the conductivity of the material as a whole. 

k app = k g + k cv + k f + k rc + k i (1.4) 

where, 

k g = conduction of air x (1 - f ), where f is volume fraction of fiber 

k cv = conduction by convection 

k f = conduction through fibers 

k rc = conduction by radiation 

k i = interaction between air and fiber. [10] 

Methodology 

To study the effect of fiber types and fiber parameters on thermal insulating properties, needlepunched 

nonwoven fabrics were produced from fibers listed in Table 1. 

The fibers were carded, crosslapped and needlepunched using four different needling densities (93, 140, 186 



and 248 pen./cm 2 ) and two 

different needle penetration 

depths (7mm and 12mm). In 

addition, meltblown PBT 

(poly(butylene 

terephthalate)) web, 40 

grams per square meter, 

supplied by TANDEC, 

University of Tennessee, 

was used. These webs were 

incorporated into the 

needlepunched nonwoven to 

form a barrier for the heat 

flux flow. 

Table 1 

SPECIFICATIONS OF FIBERS USED 

Polymer dpf Length Supplier Type 

(in) 

PET 4.0 3.0 DuPont Solid 

PET 6.0 2.5 Hoechst Celanese Solid 

PET 6.0 2.0 Hoechst Celanese Hollow 

PET 6.0 2.0 Eastman Chemical Deep Grooved 

(4DG) 

PET 1.0 2.5 Hoechst Celanese Solid 

Kevlar(r) 2.25 1.5 DuPont Solid 

The data obtained was regressed against bulk density, thickness, air resistance and fiber type. 

Testing Procedures 

The needlepunched nonwoven fabrics were tested for air resistance, thickness, grab tensile strength, basis 

weight, and apparent thermal conductivity. The procedures and equipment used are described in Table 2. 

Measurement of Apparent Thermal Conductivity (kapp) 

For measuring the apparent thermal conductivity of the nonwoven samples, the guarded hot plate instrument 

was used. The Holometrix model TCFGM guarded hot plate thermal conductance measuring system is used 

for determining the thermal performance of insulation and other materials of relatively low thermal 

conductance. When such a material, in the form of a flat slab, is exposed to different temperatures on the two 

opposites faces, heat flows across the slab resulting from a combination of conduction, convection, and 

radiation within the material. 

The effective thermal conductivity of the test samples is determined from measurements of the final surface 

temperatures, the power input to the main heater, and the geometry of the test sample, as follows: 

(2.1) 

where 

kapp: apparent thermal conductivity of the sample, W/moK 

E: main heater voltage, Volts 

I: main heater current, Amps 

S: main heater surface area, m 2 

T 1 , T 2 : temperature gradients through the samples, o C, and d 1 , d 2 : sample thickness, m. 


The needlepunched fabrics made were tested for thickness, air resistance, bulk density, grab tensile strength, 

and apparent thermal conductivity. Two samples at each data point were averaged to obtain the raw data. 



Effect of Bulk 

Density 

Bulk density was the 

most important factor 

affecting the 

apparent thermal 

conductivity of the 

needlepunched 

samples. Good linear 

Table 2 

TESTING EQUIPMENT 

Equipment 

Model number Manufacturer 

Air resistance KES-F8-AP1 Kato Tech. Co. 

Thickness Ames 282 B.C. Ames 

Tensile strength M786 Instron Co. 

Thermal Conductivity TCFGM 

Holometrix Co. 

regression fits were obtained between apparent thermal conductivity and bulk density. The statistical analysis 

showed that bulk density has a significant effect on apparent thermal conductivity at a significance level of 

99.99%. As can be seen in Figure 1, for the range of bulk densities studied, as the bulk density increased, the 

apparent thermal conductivity also increased. In the literature, for fibrous insulation, a "U" shaped curve is 

usually obtained for the effect of bulk density on conductivity [11]. In this research, only a linear relationship 

has been established due to the limited range of bulk densities investigated. Only fabrics with the highest bulk 

densities would have the durability needed in insulating textile wet processing equipment. 

Fibers with lower deniers have lower apparent thermal 

conductivity values due to higher fabric surface areas. 

On the other hand, 4DG fiber needlepunched fabrics, 

due to the unique cross section of the fibers have a 

higher surface area than lower denier fibers studied. 

The 4DG fiber surface also leads to "channeling 

effect" and traps air to provide better insulation. 

Though needlepunched Kevlar® has higher apparent 

thermal conductivity than all the other fibers studied, 

incorporation of meltblown webs into 4dpf polyester 

needlepunched structures led to a significant decrease 

in apparent thermal conductivity of the batt. This is 

due to a loss in convection and radiative heat transfer. 

The very fine denier meltblown web acts as a barrier 

for radiative heat transfer and at the same time due to 

its high surface area traps air to reduce convective 

heat transfer. This same reduction in apparent thermal 

conductivity was seen when meltblown webs were 

incorporated into 4dpf PET webs also. This is a very 

significant finding. 

Figure 1 

EFFECT OF BULK DENSITY ON APPARENT 

THERMAL CONDUCTIVITY OF 

NEEDLEPUNCHED FABRICS 

Effect of Air Flow Resistance 

In the review of literature, air permeability (reciprocal 

of air flow resistance) of the fabric played an important role in the heat transfer properties of nonwoven fabric 

[1,12]. However, most of the nonwoven examples in the literature review were for apparel insulation 

purposes, and thus had very low bulk densities. In low bulk density materials, air permeability has an very 

significant effect on apparent thermal conductivity because the larger air spaces present lead to greater heat 

transfer by convection. In the bulk density range investigated, air flow resistance did not have as significant 

an effect on effective thermal conductivity of the needlepunched fabric as did bulk density. This was 

confirmed by the statistical analysis when a significance level of 90% was obtained (Figure 2) 



Figure 2 

EFFECT OF AIR FLOW RESISTANCE ON 

APPARENT THERMAL CONDUCTIVITY OF 

NEEDLEPUNCHED NONWOVEN FABRICS 

Figure 3 

EFFECT OF THICKNESS OF NEEDLEPUNCHED 

FABRIC ON ITS APPARENT THERMAL 

CONDUCTIVITY 

. 

Effect of Thickness 

Thickness is one of the main factors influencing the effective thermal conductivity of the needlepunched test 

specimens. Apparent thermal conductivity value has been normalized for thickness, but in the data obtained 

there is a distinct difference in the thermal conductivity values of nonwovens with higher thickness and those 

of lesser thickness at the same value of bulk density. The statistical analysis suggested with 97% confidence 

that thickness has a significant effect on apparent thermal conductivity of needlepunched nonwoven fabric. 

This result is in accordance with previous research on fibrous thermal insulations [13]. An increase in 

thickness leads to a lower thermal gradient across individual air spaces, thus leading to a reduction in the 

value of convective heat transfer. Also, radiative heat transfer is reduced due to more scattering and 

absorption of radiation. This effect is not linear and is called "shadowing effect" [13]. (Figure 3) 

Effect of Fiber Type 

Four fiber parameters were investigated: denier, surface area, solid or hollow, and fiber type. It was found 

that lower denier led to a decrease in apparent thermal conductivity. There are more void spaces created by a 

thinner fiber, reducing convection, radiation and air conduction [14,15]. 

Fiber surface area also played a role in heat transfer properties of the fabric. This can be seen in the case of 6 

denier 4DG as compared to regular 6 denier fibers. The higher surface area led to more void spaces, and in 

the case of 4DG there is a "channeling effect" of the void spaces. This channeling effect is due to very narrow 

elongated voids along the fiber surface. Very minute voids are created by the unique structure of 4DG fibers 

and this resulted in the nonwoven having a lower apparent thermal conductivity by reducing radiative and 

convective heat transfer. 

Hollow fibers reduced heat conduction compared to solid fibers due to the trapped air in their interior. They 

also show some scattering and absorption of radiation in the hole in their center, reducing radiative heat 

transfer. They effectively have higher surface area than solid fibers. This effect has been confirmed in the 

literature [16,17]. 



Conclusion 

The candidate fiber 

recommended for 

insulating textile wet 

processing machinery 

incorporates meltblown 

web in its structure and has 

Kevlar® on the side that 

would be in touch with the 

equipment. This will give 

the fabric better thermal 

stability properties on that 

side. Polyester 

needlepunched fabrics and 

PBT meltblown webs 

combined together had a 

lower apparent thermal 

conductivity than all single 

polyester needlepunched 

Determinant 

Fabric 

Purchase price 

Capital for insulation 

manufacturing 

machinery 

Table 3 

BASIS FOR ECONOMIC 

THICKNESS CALCULATIONS. 

Type/Value 

PET/Meltblown/ Kevlar® 

needlepunched 

$4.91/m 2 in. 

$1.3 million 

Capital for insulation 

manufacturing 

building $500,000 

For use on equipment 

Cost of heat 

Cost of labor $22.6/m 2 

Project life 

5 years 

Textile dyeing/drying equipment 

$5.74/106Btu 

fabrics. Polyester, however, oxidizes over a long period of time due to the presence of heat, air and moisture 

at the insulation utilization site due to hydrolysis. Kevlar® on the other hand has better resistance to thermal 

degradation and provides the nonwoven with improved strength as compared to polyester. The tensile 

properties of the needlepunched nonwovens in the bulk density range studied are well above those required 

for a durable thermal insulation. 

Cost Analysis 

Determination of Economic Thickness of Insulation 

Calculations for the economic thickness of a thermal insulation are based on recommendations made by the 

U.S. Department of Energy, Office of Industrial Programs [18]. 

There are two methods widely used for determining the optimal economic thickness of an industrial 

insulation: the minimum total cost method and the incremental cost method. For the minimum total cost 

method, actual calculations for the cost of insulation and the cost of lost energy are determined at each 

insulation thickness. The thickness producing the lowest total cost is the optimal economic solution. Due to a 

large number of tedious calculations involved, this method is not very practical. On the other hand, the 

incremental (or marginal cost) method is much simpler for determining the optimal thickness. With this 

method, the optimum thickness is determined to be the point where the last dollar invested in insulation 

results in exactly one dollar in energy cost savings. At a thickness greater than that point, a dollar invested 

will result in less than one dollar in energy cost savings. For a given situation both methods will yield the 

same optimum thickness solution. 

Economic Thickness Determination 

The economic thickness was determined using the incremental cost method. It used the cost of heat and the 

cost of insulation to obtain the optimum thickness based on the life of the insulation project. Using the graphs 

and the worksheets [18] prepared by the U.S. Department of Energy, Office of Industrial Programs, the 

economic thickness is determined to be less than one inch, but the specific thickness cannot be determined. 

To determine the exact thickness mathematical calculations are found to be more suitable than using 

pre-determined graphs [18]. Table 3 lists the basis for economic thickness calculations. 



Using certain assumptions and cost, the optimum economic thickness was determined by the incremental cost 

method. The most economic thickness is determined to be 10.1 mm (0.4 in.) based on an apparent thermal 

conductivity value of 0.089 watts/mK. 

Conclusion 

The objective of this investigation was to develop and evaluate needlepunched nonwovens as thermal 

insulation for textile wet processing machinery. This purpose has been fulfilled within the limitations of the 

experimental setup. A novel needlepunched insulation has been developed by sandwiching a PBT meltblown 

web between two carded webs of PET. One side of this insulation (which is to be in contact with the textile 

wet processing machinery) is then layered with a carded Kevlar® web. The purpose of the Kevlar® is to 

prevent oxidation and degradation of the PET fibers since Kevlar® has superior thermal stability. The 

thermal insulation thus developed showed lower apparent thermal conductivity than a variety of other 

needlepunched structures studied. A cost analysis of this insulation (based on a five-year project life return of 

investment) determined the optimum thickness of such an insulation to be less than half an inch (10.1 mm), 

which is well below the industry norm. This means that the last dollar invested in the insulation project would 

be recovered by savings in energy bills after five years. The optimum thickness for a specific textile plant will 

depend upon the cost of energy, local labor rates and prevailing material costs. The tensile properties were 

also found to be adequate for commercial applications. The implementation of such an insulation project by a 

textile wet processing industry would however depend upon the competition, insulation cost, capital 

available, etc. 

The investigation into the effect of various fabric parameters such as bulk density, air permeability, etc., 

which was intended for this investigation has also been completed. For needlepunched nonwovens the bulk 

density is found to be the most significant factor determining its heat blocking properties. At higher bulk 

densities, the fabrics have higher apparent thermal conductivities, i.e. in the range of bulk densities 

investigated, lower bulk densities represent better thermal insulation. This must be balanced, of course, with 

the structural integrity requirements of the application. 

Thermal conductivity properties do not correlate with air resistance values. The thickness of the web 

however, affects the apparent thermal conductivity. At higher thicknesses, the apparent thermal conductivity 

is reduced as compared to thinner webs. This is due to a decrease in convective and radiative heat transfer 

through the web at higher thicknesses. The effect of thickness on apparent thermal conductivity of the 

needlepunched insulation was not taken into account when calculating the economic thickness of the 

insulation. Incorporation of the meltblown PBT web in the structure of the needlepunched web significantly 

reduced the apparent thermal conductivity of the nonwoven batt. This is the most significant finding of this 

investigation. Utilizing this finding can lead to superior insulation at lower cost. 

Bibliography 

1. Morris, G.J., "Thermal Properties of Textile materials," Journal of the Textile Institute, pp. T449-475, May 

1953. 

2. Wijeysundersa, N.E., and Hawlader, M.N.A, "Effects Of Condensation And Liquid Transport On The 

Thermal Performance Of Fibrous Insulations," International, J. of Heat and Mass Transfer 35, pp. 

2605-2616, Oct.1992. 

3. Bales E., "Research for Thermal Insulation," J. of Heat Transfer 90, pp. 44-45, March 1968. 

4. Bankvall, C., "Heat Transfer In Fibrous Material," J. of Testing and Evaluation, pp. 235-243, May 1973. 

5. Bomberg, M., and Klarsfeld, S., "Semi-Empirical Model of Heat Transfer in Dry Mineral Fiber 

Insulations," J. of Thermal Insulation 6, pp. 157-173, Jan 1983. 

6. Fricke, J., and Caps, R., "Heat Transfer In Thermal Insulations - Recent Progress And Analysis," 

International Journal of Thermophysics 9, pp. 885-893, May 1988. 



7. Degen, K.G., Rossetto, S., and Reinchenauer, T., "Investigation Of Heat Transfer In Evacuated Foil Spacer 

Multilayer Insulation," J. Thermal Insulation 16, pp. 140-152, Oct, 1992. 

8. Horton, C.W., and Rogers, F.T., "Convection Currents in a Porous Medium," J. Applied Physics 16, pp. 

367-370, June 1945. 

9. Kowalski, G. J., Mitchell, J.W., "An Evaluation And Experimental Investigation Of The Heat Transfer 

Mechanism Within Fibrous Media," ASME publication 79-WA/HT-40. 

10. Pelanne, C.M., "Heat Flow Principles In Thermal Insulations," J. Thermal Insulation, pp. 50-81, July 

1977. 

11. Wang, K.Y., and Tein, C.L., "Thermal Insulation In Flow Systems: Combined Radiation And 

Convection Through A Porous Segment," J. Heat Transfer 106, pp. 453-459, May 1984. 

12. Pierce, F.T., and Rees, W.H., "The Transmission Of Heat Through Textile Fabrics-Part II," Journal of the 

Textile Institute, pp. T181-T202, Sept. 1946. 

13. Speakman, J.B., and Chamberlain, N.H., "The Thermal Conductivity Of Textile Materials And Fabrics," 

Journal of the Textile Institute 29, pp. T29-T53, 1929. 

14. Rees, W.H., "The Transmission Of Heat Through Textile Fabrics," Journal of the Textile Institute 32, pp. 

T149-T165, Aug. 1941. 

15. Caps, R., Umbach, K.H., "Optimizing Polyester Nonwoven Fabric Thermal Insulation," Melland English, 

pp. E 201, May 1990. 

16. Martin, J.R., and Lamb, G.E.R., "Measurement Of Thermal Conductivity Of Nonwovens Using A 

Dynamic Method," Textile Research Journal, pp. 721-727, Dec 1987. 

17. Lee, Y.M., and Barker, R., "Thermal Protective Performance Of Heat-Resistant Fabrics In Various High 

Intensity Heat Exposures," Textile Research Journal, pp. 123-132, March 1987. 

18. "Economic Thickness for Industrial Insulation U.S. Department of Energy," U.S. Office of Industrial 

Programs, Fairmont Press Inc., Atlanta, GA, 1983. 



—INJ 



Trends In Latex Emulsions 


Comparison Of Trends In Latex 

Emulsions For Nonwovens and Textiles: China and the 

United States 

By Pamela Wiaczek, Project Manager, Polymers and Materials, 

Kline & Company, Inc., Little Falls, New Jersey, USA 

Abstract 

The U.S. and Chinese markets for synthetic latex polymers in the nonwoven and textile markets reached 

337,000 dry tons (or 744 million dry pounds) in 1996. Overall, the demand for latex polymers in these 

two market segments will grow to 377,000 dry tons (or 831 million dry pounds) in 2001. Latex usage in 

nonwovens in these two regions will reach an estimated 202,000 dry tons (or 445 million dry pounds) in 

2001, representing average annual growth of 2.2% a year. Likewise, demand in the textile market will 

grow to 175,000 dry tons (or 386 million dry pounds) in 2001. It is critical to understand that the demand 

for latex polymer in both markets in the United States will follow that of a more mature market, growing 

at approximately 2% a year. Demand in China, however, will grow by an estimated 6% a year, but from 

a very small base. 

Future demand for latex polymers in the nonwovens market will be driven by such factors as: 

● Consumer discretionary income and preference 

● The continued development of specialty niche applications 

● Capacity changes in nonwoven products 

Introduction 

"Synthetic latex polymers" are defined as aqueous emulsions that are sometimes referred to as "colloidal 

dispersions." They are applied primarily as film formers and binding agents throughout a broad range of 

end uses. 

Discussion 

Nonwovens are described as flat, flexible, porous sheet or web structures produced by binding and 

interlocking fibers, yarns, or filaments by mechanical, thermal, chemical, or solvent means. Synthetic 

latex polymers act as binders in the chemical bonding process. 

Textile materials are produced from natural and synthetic fibers having a finite length or filaments of 

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continuous length. These fibers are processed in three stages: 

● yarn manufacturing 

● fabric production, and 

● finishing. 

Latex polymers may be utilized in the fabric construction stage, however, the majority is consumed in 

textile dyeing and finishing. They serve as backcoats, hand builders, pigment binders, and flocking 

adhesives in textiles. 

Market Size 

The nonwovens markets in the United States and China are very different in both size and process 

technology. The worldwide production of nonwovens is estimated at 2.2 million tons to 2.5 million tons 

(or 4.8 billion pounds to 5.5 billion pounds) in 1994. The United States represented 43% of the 

nonwoven production, while Asia represented 27% [1]. Of the 15% of the total nonwovens market 

categorized as "other" regions of the world, Kline's estimates place the total production of nonwoven 

products in China at 160,000 tons in 1995. Nonwoven producers in China number more than 400 

companies with approximately 800 production lines [2]. 

In the United States, nonwovens production is estimated at approximately 2.3 million tons (or 5 billion 

pounds). U.S. Department of Commerce data indicates that the value of nonwoven product shipments is 

$4.3 billion in 1996. Approximately 170 nonwovens manufacturing establishments exists in the United 

States [4]. 

Historically, the U.S. nonwovens market first developed around the drylaid process technology. Over the 

last half-century, other process technologies have been successfully developed with spunbonding now 

representing about one-third of the U.S. market. In China, the market is geared more evenly toward 

spunbonding, needlepunching, and carding. 

The textile market in the United States and China is also very different in scale and structure. The value 

of U.S. textile product shipments is cited at $79.1 billion in 1995 [5]. Approximately 5,900 

establishments in the United States participate in the textile market [6]. In China, textile production in 

1995 totaled 24,576 million meters. State-owned textile mills represent an estimated 75% of the total 

production in China, however, the number of local, country-owned enterprises is growing. This is 

particularly true in the textile dyeing and printing industries in China. 

Types of Emulsions Consumed 

The types of emulsions utilized in nonwoven and textile applications in both the United States and China 

are similar, however, the degree to which the products are utilized in each country varies. Pure acrylics 

are among the major products in both countries. Likewise, styrene-acrylics are second tier latexes for 

nonwoven applications in both countries. 

Several dissimilar characteristics also exist between the two countries, as follows: 

• Scale: Emulsion consumption in the U.S. nonwovens market totals 164 thousand tons (or 362 million 

dry pounds) versus the Chinese market at 17 thousand dry tons (or 37 million dry pounds), so the United 

States is approximately 10 times larger than China. 

• Vinyl-acrylics, polyvinyl acetate (PVAc), and styrene-butadiene (SBR) are major products for 



nonwovens in the United States, but only minor products in China. 

• Vinyl acetate-ethylene (VAE) latexes are major products for nonwovens in the United States, yet are 

not consumed in China. In addition, the more specialty products such as polyvinyl chloride (PVC), 

polyurethane (PUR), acrylonitrile-butadiene, and ethylene-vinyl chloride (EVCL) are only seen in the 

United States. 

• Scale: Emulsion consumption in the U.S. textile market totals 140 thousand tons (or 310 million dry 

pounds) versus the Chinese market a 16 thousand dry tons (or 35 million dry pounds), so the United 

States is approximately nine times larger than China 

• PVAc latex is a major product for textiles in the United States, but only a minor product in China 

• SBR latex is a major product for textiles in the United States, yet not consumed in China. In addition, 

the more specialty products such as PVC, PUR, and polyolefins are only seen in the United States 

Emulsion Pricing 

In general, market prices of latex polymers in China are higher than those in the United States. The 

average price for the nonwovens market in China was about 10% higher than the United States in 1996. 

In the textile market, average prices in China are approximately 33% higher than in the United States. 

The higher prices in China can be attributed to several factors including: 

• The higher quality level of emulsions locally produced by the multinational companies in China versus 

the local producers, and the resulting gap in prices. 

• The smaller sizes, typically in the range of 30 kg to 200 kg in China, versus truckloads in the United 

States. 

• Different terms of credit coupled with the fact that many purchases in China are made on a spot basis to 

serve short-term needs 

Function of the Latex Polymer in Nonwovens 

As previously noted, latex polymers are the primary binding agent in nonwovens. As such, they are often 

referred to as "chemical binders." One of the important attributes offered by latex polymers in nonwoven 

applications is the hand of the finished product. Latexes offer the ability to modify the softness or 

stiffness of the nonwoven. The range of hand characteristics of the nonwoven is impacted by the 

selection of the latex type. Generally speaking, acrylics offer a wide range in hand from soft to stiff. 

PVAc latex possesses inherent stiffness. Other latexes such as VAE, SBR, and vinyl-acrylics impart hand 

qualities that range between the two extremes. 

Latex polymers are largely responsible for the tensile strength of the nonwoven product. In addition, 

latexes also impact other properties such as tear, grab, burst, and seam strength. As a rule of thumb, the 

latex polymers that are not self-cross-linking yield good dry strength but redisperse on exposure to water. 

Likewise, the emulsions that are self-cross-linking offer good wet strength. 

Color fastness of the nonwoven is also largely impacted by the selection of the latex polymer. Acrylic 

latexes offer the best results in terms of color fastness. At the other extreme, both PVAc and SBR latex 

polymers have poor color fastness. PVAc experiences issues with fading after washing, while SBR tends 

to yellow upon exposure to heat and light. 



Mechanical properties such as flexibility, stretch and crease recovery, and abrasion resistance, among 

others, are important attributes in nonwovens. Acrylic and SBR latex polymers typically are known for 

their good flexibility, while PVAc is viewed as more brittle. 

Other important attributes impacted by the choice of latex polymer include absorbency, flammability, 

and permeability. 

Function of the Latex Polymer in Textiles 

The function of latex polymers in the textile industry is generally categorized as coatings/backcoatings, 

hand builders, pigment binders, or flocking adhesives. In coatings, the latex polymer enhances fabric 

tensile strength, surface abrasion resistance, and stiffness. In backcoating applications, the latex provides 

strength, durability, and wear resistance. 

The selection of the latex type impacts the hand-or manner in which the textile fabric feels-by softening, 

stiffening, or adding body to the product. PVAc latex polymers typically stiffen and add body to textiles, 

while polyethylene (PE) latexes soften the products. Acrylics can be manufactured to offer a wide range 

of hand characteristics, depending upon the application. 

In pigment processes, latex polymers such as acrylics are combined with the dyes and other additives and 

then applied to the fabric surface. The latex serves to hold the color into the fabric for processes such as 

screen and engraved roll printing. 

Finally, latex polymers serve as a binder or "flocking adhesive" to adhere fibers to a cheesecloth in the 

production of imitation velour fabrics. This process is typically seen in such market segments as 

upholstery and ribbons. 

Latex Consumption 

Overall, China is an emerging market for latex emulsions. The consumption of latex emulsions in 

nonwovens and textiles in the United States is approximately 10 times larger than in China. However, as 

previously noted, the types of emulsions utilized in nonwoven and textile applications in both the United 

States and China are somewhat similar. Pure acrylics are the major products in both countries. In fact, the 

dominance of acrylic latexes in China compared to that in the United States is striking. In addition, the 

percentage of the total demand in each region represented by vinyl-acrylic emulsions is almost identical. 

As previously noted, VAE demand in the United States is significant while it is not seen at all in China, 

Finally, specialty emulsion products are consumed in the United States but not in China. 

Channels of Distribution 

The channels of distribution for supply of latex emulsions differ in the United States and China. In the 

United States, the level of captive production and imports of emulsion polymers to serve the nonwoven 

and textile markets is very minor, if it exists. In China imports are significant, representing 22% of the 

total Chinese demand in these two markets. 

Leading Suppliers 

One of the largest suppliers of latex emulsions to the nonwoven and textile markets in the United States 

and China is Rohm and Haas. In addition to Rohm and Haas, the United States is also served by three 

other significant suppliers and a host of other minor producers of latex polymers. Other leading suppliers 

of latexes in China include Union Carbide and Lan Zhou Petrochemical. 

Major Trends in the United States 



Several processing changes have impacted the U.S. nonwovens market in the past, of which some 

continue today. Among them: 

Thermal bonding: Beginning in the 1980s, the U.S. nonwovens industry saw a change from drylaid 

processing of polyethylene terephthlate (PET) to thermal bonding of polypropylene (PP) in the diaper 

coverstock segment. This negatively impacted the demand for latex polymers in this market segment in 

the 1980s and early 1990s. In addition, in the recent two to three years, the apparel interlinings and 

automotive markets have also shifted to thermal bonding, resulting in a decline of latex demand for these 

applications. 

Spunbonding: Overcapacity in the spunbonding segment of the U.S. nonwovens market, combined with 

the economics of this process, has also negatively impacted latex demand in recent years. The 

spunbonding process offers advantages in that the latex cost is cut entirely, while the fiber cost can be 

reduced by approximately one-half due to the product form. 

Spunlace: In some segments of the towels and wipes market, spunlace products are beginning to see 

acceptance. However, the major brands such as Handi Wipes and Chicks had remained with 

latex-bonded technology as of late 1996. 

Despite the negative impact of some of these changes, several niche applications exist which are viewed 

as offering a brighter potential for latex polymers in the U.S. nonwovens market. Among these is the 

baby wipe market, which is a strong consumer of VAE latexes in airlaid processes and is one of the faster 

growing segments of the nonwovens market. On the positive side, acrylic latex demand has been 

impacted by a strengthening in the market for latex-bonded acquisition layers for diapers which replaced 

tissue paper. However, even this segment is thought to be at risk for a potential shift to thermal bonding 

technology in the future. In addition, the imitation leather sector offers opportunities for PVC and PUR 

specialty latex polymers. Finally, the roofing membrane market offers opportunities for SBR and acrylic 

based latexes. 

Opportunities also exist in niche segments of the U.S. textile market. As a result, much of the new 

product and application development by latex producers centers around these new opportunities. For 

example, Para-Chem has developed a new acrylic copolymer that improves strength yet offers softness 

for backcoating applications. Para-Chem is also promoting a new acrylic copolymer with flame-retardant 

properties for both nonwovens and textiles. Likewise, Scott Bader is promoting a blend of acrylic and 

acrylonitrile polymers for better color values in pigment dyeing. Finally, VAE latex has found success in 

flocking of polyolefin ribbons. 

Consolidation has occurred in the nonwovens industry as a means of addressing changing market 

conditions and growing share. Examples include the merger of Kimberly-Clark and Scott Paper Co. in 

diapers, Proctor & Gamble's acquisitions in Europe and South America in diapers and feminine products, 

and Tyco's acquisition of medical products manufacturer Kendall, among others. 

Major Trends in China 

Similar to the United States, some process changes are occurring in both the nonwoven and textile 

markets in China that will impact the demand for latex polymers. Among them: 

• In nonwovens, a shift in processing from drylaid technologies has occurred in the last 10 to 12 years. 

The result is that the percentage of nonwovens production represented by needlepunched drylaid 

products has declined significantly and chemical-bonded drylaid products have marginally declined 



while spunlaid and melt blow processing has increased [7]. The primary impact of these technologies 

upon latex polymer demand has been that such newer technologies do not always utilize latexes. 

• In the textile industry, China is being severely impacted by loss of business to other regions, including 

Indochina, the Indian subcontinent, and the Middle East. Part of the shift is attributed to substandard 

product quality from textile materials manufactured in China. The technology employed in a number of 

textile processes is not as well developed in China as in other regions of the world. Investments in new, 

higher quality processing technologies have not been sufficient to stem the tide of competition. 

The outlook for the nonwoven and textile industries in China is varied. In the nonwovens market, 

opportunities for spunlaid technologies are viewed as greater than that for traditional products. However, 

the overall Chinese market for chemically bonded nonwovens is still viewed as a high growth potential 

from its current base. Thus, latex polymer demand for existing and new chemically bonded products will 

be strong. On the other hand, the textile market in China is not expected to grow a great deal over the 

coming five years and the potential exists for continued declines in some segments. The longer-term 

prospects will be more promising if state-owned textile mills are able to invest in new technologies to 

make themselves more competitive. In terms of segments of the market where latex polymers are 

consumed, some growth in pigment binding is anticipated. 

Opportunities for more specialized product developments exist in China. In the nonwovens market, some 

technical development has been directed at formulating products with a suitable cost versus performance 

balance for applications in the domestic market where dry cleaning practices are not as common or 

severe. In another nonwoven application, low formaldehyde products are being used in certain clothing 

types such as baby wear and undergarments. 

Conclusions 

What does all of this mean for latex emulsions? In general, the nonwoven and textile markets will 

continue to be important to demand for latex polymers. Opportunities for growth exist in both the United 

States and China. Overall, the demand for latex polymers in these two market segments will grow to 377 

thousand dry tons (or 831 million dry pounds) in 2001. Latex usage in nonwovens in these two regions 

will reach an estimated 202 thousand dry tons (or 445 million dry pounds) in 2001, representing an 

average annual growth of 2.2% a year. Likewise, demand in the textile market will grow to 175 thousand 

dry tons (or 386 million dry pounds) in 2001. 

So, growth will occur in both market segments, albeit at different paces for the two countries. 

Consumption of synthetic latex polymers in the U.S. nonwoven and textile markets will reach 333 

thousand dry tons (or 734 million dry pounds) in 2001. This represents average growth of 1.8% a year in 

the coming five years in the United States, typical of a more mature market. 

Demand for latex polymers in the Chinese nonwoven and textile market will increase from 33 thousand 

dry tons (or 72 million dry pounds) in 1996 to 44 thousand dry tons (or 97 million dry pounds) in 2001. 

This is representative of a 6.1% a year growth rate for China, but from a very small base. 

References: 

1. Smith, T., and Smith, D., Nonwoven Markets 1996 International Factbook and Directory, Miller 

Freeman, Inc., San Francisco, 1996, p. 7. 

2. China Nonwoven Association 

3. 1995 Annual Survey of Manufacturers, U.S. Department of Commerce, Washington, DC, January 



1997, p. 2-11. 

4. 1992 Census of Manufacturers, U.S. Department of Commerce, Washington, DC, May 1995 p. 

22E-10. 

5. 1995 Annual Survey of Manufacturers, U.S. Department of Commerce, Washington, DC, January 

1997, p. 2-10 and 2-11. 

6. 1992 Census of Manufacturers, U.S. Department of Commerce, Washington, DC, March and May 

1995, p. 22A-9, 10; 22B-12, 13, 14; 22C-9, 10, 11; 22D-9; 22E-9, 10, 11. 

7. China Nonwoven Association 

This paper was originally submitted for publication in the TAPPI_Journal. The INJ_editors and 

publishers wish to express their appreciation to TAPPI_for their support and encouragement. 



- INJ 





Fiber Renaissance For 

The Next Millennium 

By Arun Pal Aneja, Dacron® Research Laboratory, DuPont Company, Kinston, NC 

Abstract 

As we enter 21st century, technical advances are dramatically influencing the world of fibers, fabrics and 

textiles. Today, technology can provide us with fabrics that imitate and actually improve upon nature's best 

fibers. In the next millennium, textiles will not just be an extension or simple alternatives to natural or 

synthetic fibers, but will provide superior functionality in broad and emerging sectors of the economy from 

space to super conductivity and agriculture to geotextile. This will be accomplished through modern business 

strategies for enhanced stakeholder value and highly efficient production schemes with no adverse impact on 

the environment and development of precisely specified molecules for new textile platforms. 

Introduction 

We are living in a world in which technology is advancing at such an astonishing rate that most of us have 

difficulty comprehending the overall impact it has, and will continue to have, on our lives. Cloning of adult 

mammals, World Wide Web, smart materials, high-speed processors and wonder drugs continue to dazzle us 

almost on a daily basis. The textile industry has kept pace and technology today can provide fabrics that go 

well beyond the best that nature has to offer. It is, indeed, a narrow view to think of textiles as a fixed 

discipline of making "strings." It is much more diverse than that and most importantly, it is in a state of flux 

in response to changing needs of society and new innovations. The inherent characteristics of new textiles 

underpin the functional and aesthetic qualities of these many and varied applications from the world of 

fashion to agriculture, medical, aerospace, reinforced composites and architecture. There has been rapid 

growth in polymer, material, information and biological sciences. The advance, in these adjacent sciences 

and their inevitable interface, will catalyze the reconceptualization of tomorrow's textiles. This concept of 

interdisciplinary research, development and product innovations will lead to new textile platforms for the 

next millennium. 

Looking back on the history of fibers, you will find that most natural fibers originated in Asia. Cotton and 

silk are native to China and India, while wool was first put to practical use in Central Asia. It is widely 

known that the Silk Road was opened by the strong desire of Western peoples to acquire silk products 

originating in China 

Meanwhile, the history of man-made fibers began with the invention of rayon in the late 19th century. 

file:///D|/WWW/inda/subscrip/inj99_2/fiber.html (1 of 7) [3/21/2002 5:08:37 PM]


Figure 1 

GLOBAL GROWTH OF MAN-MADE FIBERS 

OVER THIS CENTURY 

Following the invention of nylon in 1935 by Wallace 

Hume Carothers at DuPont, acrylic and polyester 

fibers were developed [1], leading to increased 

research activities for a variety of new materials 

comprised mainly of these three major synthetic 

fibers. New fiber-making technologies suitable for the 

new materials were invented. New high-performance 

fibers including, among others, carbon and aramid 

fibers, are also beginning to mature. Thirty-five years 

after the invention of nylon, world-wide synthetic 

fibers surpassed man-made cellulose. Today, 

synthetic fibers have surpassed natural fiber 

production (Figure 1). 

Trends and Current Concerns 

Over the last 60 years the textile business has enjoyed 

rapid growth in synthetic fibers, fueled largely by 

seminal discoveries in polymer and fiber science. Fiber and textile manufacturing facilities also have 

undergone enormous improvements in automation and simplification where large volume fiber production 

facilities today may require only tens (instead of hundreds) of personnel for their operation. 

Fibers that have ease of care and natural-like 

aesthetics have been major themes in recent decades, 

with high performance and specialty fibers taking on 

particular significance. Fiber and fabric tests, critical 

to product quality have relied largely on destructive, 

off-line methods. Advances in testing and quality 

control promise to have a major impact on first pass 

product yields and product quality. 

Figure 2 

DISCOVERY OF TEXTILE FIBERS 

(The fibers discovered by DuPont or in collaboration 

with DuPont are to the right of the worldwide 

synthetic fiber growth curve. The fibers discovered 

by the rest of the world are to the left of the curve) 

DuPont pioneered the fiber revolution of the 20th 

century (Figure 2). Looking to the next millennium, 

the textile industry stands in stark contrast to its 

preeminent position of just 20 years ago. Many of the 

synthetic fiber products that once fueled the rapid 

growth of the industry have become mature 

commodity products now characterized by low 

growth and lower profit margins. Intense global cost 

pressures, higher consumer expectations, a highly 

diverse customer base and reduced R&D spending 

have all contributed to the current state of affairs. The 

challenge for the future is to revitalize the industry - a 

fiber renaissance - through technological innovations 

in products and manufacturing and to reevaluate business practices in a global context. 

Ecological Factors 

The delicate balance that exists in the planet's ecosystem is well understood around the world and grassroots 

organizations exist in most countries for its preservation. There is also increased awareness of the harmful 

environmental effects of most manufacturing processes. If textile industry is to survive, it too must take a 



leading role in "environmentalism." Indeed, companies researching new textiles are making ecology a 

primary concern. Some, in fact, will not develop new products unless they can be made safely and without 

deleterious impact to the environment. The companies are fully aware of the fact that world's resources will 

soon be depleted unless major changes are implemented in manufacturing systems. These are: 

● Waste elimination 

❍ Reduce 

❍ Reuse 

❍ Redesign 

● Energy conservation 

● Reclamation 

● Recycle 

All steps of the textile processing value chain from raw material conversion to fabric disposal must be 

environmentally friendly. We must close the recycling loop (polymer, fiber, product to landfill) for all 

polymers with no material ever entering the landfill. 

Processes of the Future 

Commodity fibers technology is generally mature and broadly available to investors. Hence, competitive 

advantages in process technology around the world are shrinking fast. The progress in process technology for 

the future will mainly be driven by the following factors: 

● Knowledge intensity 

● Highly competitive market with resultant ultra-high quality products and productivity 

● Fiber production by a few large companies with availability of diverse fibers 

● Strong business alliance for ease of market access 

● Capacity rationalization and decentralized business structures for shareholder value 

● Strategic shifts for competitiveness and reduced risk 

● Collapsed value chain with control moving downstream 

● Consistent global pricing 

● Rapid information exchange 

The last decade in the textile sector has seen major reduction in cost and productivity improvement. This is 

due to innovations in processing technologies of automation, increased spinning speed, production capacity 

and process simplification. The production cost variance of fiber manufacturers is governed by two factors: 

(1) investment cost per ton of fiber dictated by economy of scale and (2) price advantage of basic feedstock. 

The investment cost for new plants are determined by raw material conversion cost (size of reactor), 

operating speeds of spinning, drawing and texturing, and quench technology to obtain the desired fiber 

morphology. 

Future fiber manufacturing technology must also accommodate mass customization in the market place. 

Hence, a system of specialized product variants for small-lot production will provide high value-added 

products to the consumer. The challenge for the future will be the development of efficient small-scale 

production technology for such products. 

Biotechnology 



The route to new polymer platforms will most likely emerge from biological synthesis of polymeric 

materials for the precise synthesis of modular building blocks for polymeric materials. The need for exquisite 

tailoring and uniformity of macromolar structure has never been greater. Macromolecular synthesis of 

polymers by biological route will take on increasing importance and traditional chemicals will be made 

through biotechnology. It is no longer necessary to start with a barrel of oil to produce chemicals. Corn, 

beets, rice - even potatoes - make great feedstocks. Yeast, grain and water can be used to make a fine quality 

ale, or for that matter, other molecules. Comfortable, easy-care apparel may soon be made with fibers spun 

from chemicals that have been fermented from sugar. [2] 

DuPont is building a pilot plant that uses genetically altered microorganisms to produce basic chemicals that 

are not made from petroleum. Biotechnology will ferment glucose and produce intermediates that can then 

be used to make nylon and polyester. The process is less expensive and kinder to the environment than 

traditional chemical methods. Our progress is far exceeding our expectations. If the pilot goes well, the 

process could be commercialized in the near future. 

Figure 3 

PRECICELY SPECIFIED MOLECULES — 

BIOSYNTHETIC SCHEMATIC 

The transformation of sugars into alcohol by 

microscopic organisms has been known for 4000 

years. With the advent of genetic engineering, we can 

now harness the sophistication of biological systems 

to create molecules that are difficult to synthesize by 

traditional methods. 

For example, the polymer polytrimethylene 

terephthalate (3GT) has enhanced properties as 

compared to traditional polyester (2GT). Yet the 

commercialization has been slow because of the high 

cost to make one of 3GT's intermediates. Through 

recombinant DNA technology, DuPont and Genecor 

Figure 4 

UNIQUE STRESS-STRAIN PROPERTIES 

OF SPIDER SILK 



have created a single microorganism with all the 

enzymes to convert cornstarch to sugar into this 

intermediate. This breakthrough is opening the door 

to low-cost, environmentally sound, large-scale 

Figure 5 

MATERIALS REVOLUTION OF THE 21ST 

CENTURY 

production of this enhanced polyester that will eventually approach the cost of traditional polyester. With 

two decades of research, DuPont is making an ambitious push in biotechnology that may transform DuPont 

and the textile industry. Today, we have two classes of materials in man-made fibers: man-made cellulosics 

made from natural sources such as pulped wood, cotton or vegetable materials; and true synthetics made 

from products of the petrochemicals and natural gas industries. Tomorrow, we will have a new class of fibers 

- natural synthetics made from agricultural crops - and new polymer and fibers that we have not even 

conceived. 

The success of our initial demonstrations in creating synthetic spider silk illustrates the new materials 

revolution that will be ushered into the 21st century. By using recombinant DNA and learning exactly how a 

spider makes its silk, DuPont scientists have created synthetic spider silk as a model for a new generation of 

advanced materials. For spider silk, we use advanced computer simulation techniques that design a 

molecular model to integrate all the information available to date about the structure of this amazingly strong 

and elastic fiber. Synthetic genes are then designed to encode gene matching the silk proteins (Figure 3). 

These genes are inserted into yeast and bacteria to produce the silk proteins. The protein is dissolved and 

then spun into biosilk fibers. 

Spider silk is the most dramatic example of a sizable family of biopolymers possessing a combination of 

properties that synthetic materials cannot yet approach. With its lightweight, tough and elastic properties, our 

learnings from biosilk may improve the properties of our existing products such as Lycra® and nylon. 

Synthetic spider silk may help create super-performing garments of the future (Figure 4). More importantly, 

the new generation of advanced materials from spider silk and biotechnology research have the potential to 

transform our lives in countless ways we can scarcely imagine. 

Engineered/Smart Performance Fibers 

The degree to which it is possible to engineer textiles today is truly astonishing. There is an increasing need 

for fabrics that can combine strength, functionality, fabric handle/tactility and enhanced mill value; all of this 

at competitive cost. Natural fibers, which dominated textile commerce until a few years ago, can be 

identified as the first generation (Figure 5). Synthetic fibers such as nylon, polyester and polypropylene, 

which were in response to improvements in natural fibers and currently dominate, are the second generation. 

The third generation textiles and beyond are not simply alternatives to natural or synthetic fibers but must 

provide superior functionality in broad emerging sectors of the economy from space to super conductivity 

and agriculture to geotextiles. 

Table 1 

PRODUCT TRENDS - 'SUPER' FIBERS 

Modulus gpd/(Gpa/gm/cm 3 ) Strength gpd/(Gpa/gm/cm 3 ) 

Theoretical Observed Theoretical Observed 

PET 1023/1.12 160/0.18 232/0.25 9.5/0.01 

Nylon 6 1406/1.53 50/0.06 316/0.35 9.5/0.01 

PAN 833/0.91 85/0.09 196/0.21 5/0.006 

As the interface between polymer science and biotechnology merges, textiles will evolve to adaptive 

technology-textiles that adapt to the environment around you. [3,4] Today's clothing is essentially passive. 



Table 2 

PRODUCT TRENDS - FUNCTIONAL FIBERS 

Textile Functions Application 

Thermal 

High Temperature Insulation 

Electrical 

Grounding, Signal Transmission 

Optical 

UV Protector, Light Refraction, 

Communication 

Acoustic 

Sound Absorbing 

Magnetic 

Magnetic Filaments 

Separation/Absorption Gas/Water Purification, 

Medical Applications 

Adhesion 

Hot Melt Adhesion, Concrete 

Reinforcement 

Materials 

Anti-Bacteria 

Barrier Properties 

Stretch 

Pillows, Geriatric/Baby Clothing 

Waterproof, Water-Perishable 

Comfort, Fit 

you cooler. This places a whole new meaning to smart, intelligent garments. 

Your clothing reacts only 

after your body does 

something. With Lycra®, 

your clothing stretches and 

moves as you move. With 

Coolmax®, your clothing 

wicks moisture away after 

your perspire. The 

clothing of the 21st 

century will be active. 

Your clothing will 

recognize the environment 

surrounding you and adapt 

to that environment. 

Instead of waiting for you 

to become hot and 

perspire, your clothing 

will sense that it is hot 

outside and adapt to make 

With the advent of high-strength fibers, we can now aspire to approach the theoretical limit in a whole host 

of functionalities. The strength of existing synthetic fibers can be increased many times (Table 1). Fiber 

functionality will be improved (Table 2) to yield novel applications in the future. 

Conclusion - The Emerging Paradigm 

The essence of new product development in fiber 

science during the 20th century has followed a 

relatively narrow and perhaps limited route of 

development. Fibers are made from either 

condensation or addition-type polymer platforms. The 

fiber may have polymer modifications, contain 

additives or be altered on the surface. This has 

resulted in textiles from nylon and Dacron® which 

may be cationic dyeable, flame retardant and with 

whitener/delusterant features available in a variety of 

cross section and surface treatments. 

The next century, however, will demonstrate the 

seemingly unlimited power of the synergy of diverse 

disciplines as borders between material science, 

Figure 6 

EMERGING PARADIGM FOR 

TEXTILE FIBER SCIENCE 

biological science and information science blur and erode (Figure 6). Today the breadth of complementary 

technologies is far greater. In the future fiber molecules will be designed, engineered and produced more 

efficiently than ever before due to advances in combinatorial chemistry, robotics, nanotechnology, 

bioinformatics, spectroscopy, and high-throughput screening. 

We will continuously seek to express a desired property in a molecule or a material, whatever be the 



composition and the structure, and develop strategies towards building precise molecules with desired 

properties and functions [5,6]. This will finally result in smart textile materials with attributes of selectivity, 

sensitivity, shapability, self recovery, self repair, self diagnosis, self tuning and switchability. 

References 

1. Hiratzuka, S. 1996. "Present Situation and Future Outlook for Technological Developments in Man-Made 

Fibers," JTN, July, 1996, pp. 56-76. 

2. Siegel, D&S. Birk 1998. "Fiber Development in 21st Century," Mark & Spence Lingerie Conf., UK. 

3. Aneja, A. P. 1994. "Wear No One Has Made Before," Chemtech, August, 1994, pp. 48-52. 

4. Aneja, A. P. and Popper, P. 1997. "Trends in U.S. Fiber Technology," Proceedings of the International 

Conference on Advances in Fiber and Textile Science and Technology, Mulhouse, France, April, 1997. 

5. Aneja, A.P. and J.P. O'Brien. 1999, "21st Century Fibers." Int. Fiber J., August 1999. 

6. O'Brien, J.P., and Aneja, A.P., 1999. "Fibers for the Next Millennium." J. of Soc. of Dyers and Colourists, 

U.K. Accepted for publication. 

—INJ

1999 - Volume 2 - Journal of Engineered Fibers and Fabrics

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