2001 - Volume 2 - Journal of Engineered Fibers and Fabrics

Nonwovens
INTERNATIONAL
Journal
A Science and Technology Publication
Volume 10, No. 2 Summer, 2001
Wet Process Drainage — Effects of White Water Chemistry
and Forming Wire Structures
Effects of Water On Processing and Properties of
Thermally Bonded Cotton/Cellulose Acetate Nonwovens
Microstructural Analysis of Fiber Segments In Nonwoven Fabrics
Using SEM and Image Processing
The Role of Structure On Mechanical Properties of Nonwoven Fabrics
Studies on the Process of Ultrasonic Bonding of Nonwovens:
Part 1 — Theoretical Analysis
Pira Abstracts ... Patent Review ... Researcher’s Notebook ...
Technology Watch ... Director’s Corner ... The Association Page
Sponsored By

Joint INDA-TAPPI Conference
Major Merger!
Big Success!
At the request of the
industry, INDA and
TAPPI combined their
technical conference to
produce the largest
nonwovens technical
conference in the world.
A total of 550 people
from around the world
attended INTC-2000.
Leading Edge
Information:
• Polymers & Fibers
• Properties & Performance
• Process Technologies
• Filtration
• End-uses
• Binders & Additives
• Wetlaid
• Absorbents
• Barriers
• Melt Extrusions
• Hydroentangling
• Airlaid
• Mats
• Biodegradable Polymers
• Sustainable Polymers
• Multi-component Fibers
• Microfibers
• Composites & Laminates
• State of the Art Information
Executives from
Around the World
Will Attend INTC
... The Place
to Network:
• Nonwoven Fabric
Producers
• Converters of Nonwoven
Fabrics
• Suppliers to Nonwoven
Fabric Producers
For Managers with
Responsibility for:
• New Product Development
• Research & Development
• Technical Marketing & Sales
• Testing & Quality Control
Please complete and return to INTC or fax to 919-233-1282.
Yes, please send me more information on: ❏ Attending ❏ Tabletops
Name: __________________________________________________________ Title: _________________________
Company: _____________________________________________________________________________________
Address: ______________________________________________________________________________________
City _________________________________________________________________________________________
State _________________________________ Country ________________ Zip/Postal Code ____________________
Telephone: ________________________
Fax: ________________________ e-mail: ___________________________
Return To: INDA, P.O. Box 1288, Cary, NC 27512-1288, 919-233-1210, Ext. 0, Fax 919-233-1282, www.inda.org

Nonwovens
Nonwovens
INTERNATIONAL
Journal
A Science and Technology Publication
Vol. 10, No. 2 Summer, 2001
The International Nonwovens Journal Mission: To publish the best peer reviewed research journal with broad
appeal to the global nonwovens community that stimulates and fosters the advancement of nonwoven technology.
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
856-256-1040
rjnonwoven@aol.com
D.K. Smith
480-924-0813
nonwoven@aol.com
Association Editors
Cosmo Camelio, INDA
D.V. Parikh, TAPPI
Teruo Yoshimura, ANIC
Production Editor
Michael Jacobsen
INDA Director of Publications
mike@jacorpub.com
ORIGINAL PAPERS
Wet Process Drainage — Effects of White Water Chemistry
and Forming Wire Structures
Original Paper by Daojie Dong, Owens Corning
Science and Technology Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Effects of Water On Processing and Properties of Thermally Bonded
Cotton/Cellulose Acetate Nonwovens
Original Paper by Xiao Gao, K.E. Duckett, G. Bhat and Haoming Ron,
University of Tennessee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Microstructural Analysis of Fiber Segments In Nonwoven Fabrics
Using SEM and Image Processing
Original Paper by E. Ghassemieh, H.K. Versteeg and M. Acar, Wolfson School
of Mechanical and Manufacturing Engineering, Loughborough University . . 26
The Role of Structure on Mechanical Properties of Nonwoven Fabrics
Original Paper by H.S. Kim and B. Pourdeyhimi, Nonwovens Cooperative
Research Center, College of Textiles, North Carolina State University . . . . . 32
Studies on the Process of Ultrasonic Bonding of Nonwovens:
Part 1 — Theoretical Analysis
Original Paper by Zhentao Mao and Bhuvenesh Goswami,
School of Textiles, Clemson University . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
DEPARTMENTS
Guest Editorial 3
Researcher’s Toolbox 4
Director’s Corner 7
Technology Watch 10
Nonwovens Web 12
Nonwovens Patents 48
Worldwide Abstracts 53
The Association Page 56
Meetings 57
EDITORIAL ADVISORY BOARD
Cosmo Camelio
INDA
Roy Broughton Auburn University
Robin Dent Albany International
Ed Engle
Fibervisions
Tushar Ghosh
NCSU
Bhuvenesh Goswami Clemson
Dale Grove
Owens Corning
Frank Harris HDK Industries
Albert Hoyle Hoyle Associates
Marshall Hutten Hollingsworth & Vose
Hyun Lim E.I. duPont de Nemours
Joe Malik
AQF Technologies
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
NCSU
Art Sampson Polymer Group Inc.
Robert Shambaugh Univ. of Oklahoma
Ed Thomas
BBANonwovens
Albin Turbak
Retired
Larry Wadsworth Univ. of Tennessee
J. Robert Wagner Consultant
INJ Spring 2001 1

The International Nonwovens Journal is brought to you from
Associations from around the world. This critical technical publication
is provided as a complimentary service to the membership
of the Associations that provided
the funding and hard work.
PUBLISHER
INDA, ASSOCIATION OF THE NONWOVEN FABRICS INDUSTRY
TED WIRTZ
PRESIDENT
P.O. BOX 1288, CARY, NC 27511
www.inda.org
SPONSOR
TAPPI, TECHNICAL ASSOCIATION OF THE PULP AND PAPER INDUSTRY
WAYNE H GROSS
EXECUTIVE DIRECTOR/COO
P.O. BOX 105113
ATLANTA, GA 30348-5113
www.tappi.org

GUEST EDITORIAL
CONTINUE THE
JOURNEY
By Wayne Hays
Former INDA Chairman and Recipient of the
IDEA 01 Lifetime Achievement Award
Conventional wisdom suggests that
Research and Development is essential
to the creation and ongoing success of
an industry as well as individual companies
within an industry. The nonwoven
industry is a prime example of the role
that R&D has played in nonwoven’s brief
history of some
60 years.
I have spent
almost 50 years
associated with
nonwovens and
have had a ringside
seat in the
dynamic growth
of the business
from its infancy to a major business segment.
It is my intent to hit some of the
highlights of this growth with a special
emphasis on the role that R&D played.
My use of the term R&D is in its broadest
sense, which includes process invention,
modification and control; product
invention and modification; and market
research and sales development. Perhaps
nonwoven technology growth is a better
term than R&D since I look at the whole
chain of events as the end result of technical
development.
My introduction to nonwovens came at
Callaway Mills, La Grange, GA, in 1953.
I was happily involved in R&D with a
broadly diversified textile firm when the
boss called me to his office and informed
me that “We are going into nonwovens
and you have the project.” I knew nothing
of nonwovens beyond the word, but within
a year submitted a proposition to
install a pilot line using Rando Webbers
to produce industrial nonwoven fabrics. I
was then “thrown out” of R&D and transferred
to a production unit that grew to
four lines. Our plans centered on automotive
products (backing for vinyl coatings),
chaffer fabrics for tires, shoe findings
and interlinings.
At this time in history, there were four
or five nonwoven producers in the country
(Pellon, Chicopee, and West Point-
Pepperell being the major players); all
were using proprietary technology
invented and modified for specific markets.
Total sales were around $5 million.
Great secrecy surrounded the “business.”
As Technical Director of a small production
unit, I found that I had to invent the
product, develop the process and then go
out and sell the product since our industrial
sales force was unable to handle this
“new product.” In fact, we had to invent
the market and then invent the customers.
In 1960, I joined Kendall in Boston,
which had been a pioneer in nonwovens
for over 20 years. Their output came from
three proprietary lines making specialty
products for the electrical, graphic arts
and dairy industries. A “Nonwoven
Division” was formed in 1960 with total
sales of a little over $3 million! By 1970
this “new” division was approaching
$100 million in sales!
So what happened to make this sleepy
little business explode during the 1960s
and ’70s? Major new products were
invented and marketed using nonwovens.
Prime examples include: disposable
diapers by P&G, followed by many
imitators; surgical packs and gowns plus
a host of other hospital products from
Kimberly-Clark, J&J, DuPont and
Kendall; and major new industrial fabric
markets created by DuPont and others.
These new markets were a direct result
of a bewildering array of new technologies
introduced by companies both outside
and inside the textile industry. It
seemed that everyone was getting into the
act! The paper industry introduced both
wet and dry nonwovens; Kimberly-Clark
brought forth Kaycel and Kimlon.
DuPont developed flash spun and spunbond
nonwovens, Monsanto developed
chemical spun products, and Exxon
invented melt blown nonwovens. It
became obvious that hundreds of millions
of dollars were being spent by
diverse industries to get a piece of the
burgeoning nonwovens industry. In 1968,
we established a trade association
(INDA) to encompass this wide array of
interests to promote the business.
The slow, simple, inexpensive textile
equipment that started the nonwoven
business underwent massive technical
innovation to stay in the game in face of
the assault from outside. In 1962, Kendall
helped P&G invent the disposable diaper
topsheet. We used a 40-inch card line
running 20 yards/minute. By 1964, we
were “stretching” a 40-inch card web to
60 inches and running at 60 yards/min.
By 1966, we “stretched” a 40-inch card
web to 90 inches and ran at 90 yards/min.
This stretched web was an innovation
that forecast the high-speed randomizing
cards specifically designed for nonwovens.
Today, reportedly, there are fivemeter
wide card lines capable of operating
speeds up to 1000 meters per minute!
Since I entered the industry, the nonwovens
business in North America has
grown from approximately $5 million to
the current $3.8 billion and 25.6 billion
yards (INDA 2000 Estimates). Vast technology
changes have occurred.
So, is it all over? Of course not! Fifty
years from now, the industry will be as
different and advanced from today as
today is from when I started in 1953.
Leading the charge to make this happen
will be the hundreds of R&D people currently
working on nonwovens and the
hundreds that will follow to keep the revolution
going.
Have a nice journey!
— Wayne Hays
INJ Summer 2001 3

INJ DEPARTMENTS
RESEARCHER’S
TOOLBOX
Useful Microwave Technology
In a few short years, the handy
microwave oven has become very ubiquitous
(ubiquitous: adj, seeming to be
present everywhere). In view of its
speed, economy, efficiency and convenience,
it is not too surprising that this
tool has made its way out the kitchen
into a wide variety of other applications.
The adaptation of microwave technology
to applications within the textile
and nonwovens industries has been
somewhat slow and still rather limited.
Through the efforts of several groups,
however, this situation is changing, and
the microwave system is finding its way
into numerous uses in the production
plant and also in the laboratory.
The first commercial use of
microwave heating for a textile drying
unit operation was probably the application
to drying rayon filament yarn
bobbins. In this application, the wet,
freshly spun and washed filament bobbin
was placed on a conveyor that slowly
passed through a zone of microwave
radiation. Each individual bobbin was
rotated on its axis as it slowly traversed
its path through the drying zone.
Bobbins of dry filament were removed
from the unit.
The first use of a microwave system
in the laboratory was undoubtedly the
drying of small textile fabric samples as
a part of the determination of moisture
content. For this application, the speed
and convenience were unparalleled by
other methods. However, this method
and other similar trial efforts highlighted
a major problem with the microwave
systems available — uniformity of the
treatment. In the kitchen microwave
oven, the target is often on a turntable to
provide multiple passes in front of the
source to hopefully even out randomly
occurring hotspots. Unless the treatment
is done uniformly, hotspots can
develop, resulting in over-heating in
some areas and under-heating in others.
To correct this problem, recent work
has focused on the use of “waveguides”
to serpentine the microwave energy
back and forth across whatever material
is being treated. With proper design of
the waveguides and supporting equipment,
a specific environment for the
particular wavelengths can be created to
provide a controlled distribution of the
microwave energy, making it possible to
achieve uniform exposure to any material
moved though a channel or space. In
some designs, the waveguide itself acts
as the treatment space and the positioning
(top, bottom, middle) of the material
as it travels through the space can
provide additional control over the
energy picked up by the material.
With this improved uniformity in distribution,
some amazing results can be
achieved. Two different fabrics can be
passed through a carefully designed
channel or oven plenum, the one fabric
entering wet and the other being dry. On
emerging, both of the fabrics are at an
equal level of dryness, with no overheating
of the dry fabric. This is the
type of result that technologists have
hoped for from microwave technology,
and now it appears to be available.
One company that has been a leader
in this work is Industrial Microwave
Systems (IMS) of Morrisville, NC
(IMS, 3000 Perimeter Park Drive,
Morrisville, NC; 919-462-9200;
www.industrialmicrowave.com). Their
patented design concept is called the
“Planar Drying System” and it uses
microwave energy focused at specific
angles to achieve various treatment possibilities.
Some of their applications
have involved treating tubular knits,
sheets of individual yarns in yarn sizing
applications, and others. In a system
designed for terry towel drying, faster
production speeds were possible with
the uniform treatment. An additional
benefit in this case was that the fabric
had good softness, even though a chemical
fabric softener was not employed.
This method has also ben applied to
the drying of carpet tile. In this application,
uniform drying can be achieved
without damaging the backing or substrates,
and there was no heat degradation
of the carpet material.
Significantly, substantially increased
drying speeds can also be achieved.
Installations have been made up to 30-
feet wide and material can be treated in
a thickness up to two inches.
This company has recently become
involved in several nonwoven applications,
one of which has been assisted by
a grant from the federal Department of
Energy, which is interested in the energy
saving possibilities with this type of
system. This has involved direct drying,
drying of printed webs and coated
webs, as well as treatment and drying of
composite and laminated structures.
The system has also been applied to
thermosol dyeing; in this case the excellent
uniformity has virtually eliminated
the usual liquor migration in the treated
fabric, resulting in more uniform dye
distribution. With a suitable design,
microwave drying in a dye beck or jet
dyeing unit can be achieved with a temperature
variation within the fabric rope
of only 0.1 0 C.
The beauty of the microwave system
is the fact that the energy absorption can
be controlled to a rather fine degree.
The oscillating microwave energy is not
absorbed to any degree by nonpolar
materials. This includes most polymeric
4 INJ Summer 2001

RESEARCHER’S TOOLBOX
materials and most fibers of interest to
the textile and nonwoven industries.
The polar water molecules held within a
nonpolar matrix do absorb the energy
very efficiently, as they attempt to oscillate
in a synchronous manner to the
microwave oscillations. Because of the
velocity of the oscillations, the water
molecules become heated, putting them
in an ideal condition to be evaporated
from the substrate.
As soon as the substrate has lost its
water content, no further absorption of
the microwave energy occurs, and so
the substrate does not heat up, but can
actually begin to cool. As a consequence,
the energy absorption can be
very specific to water if the proper system
is employed.
Other molecules in addition to water
will absorb microwave radiation, so
applications beyond drying are also
possible. Metals absorb energy from a
microwave source. This feature results
in some limitations, but also in some
unique applications. For example, fine
metal powder can be suspended in an
inactive medium, which is printed onto
a substrate. Only the printed pattern is
heated as the substrate traverses a treating
system. Many other variations have
been conceived for exploitation of the
system.
Numerous laboratory uses for
microwave treatment are evolving and
finding utility in a variety of applications.
These will be discussed further in
a subsequent issue of the International
Nonwovens Journal.
Nonwoven Processing Equipment at
Texas Tech
A frequently encountered problem in
nonwoven development work: A good
concept needs further work and some
pilot trials, but the necessary equipment
is not available!
One of the most effective solutions to
this dilemma is to seek the necessary
equipment elsewhere and to make
arrangements to use the equipment on a
temporary basis. In these circumstances,
the facilities at various universities
is often the answer. Such facilities
can generally be leased or otherwise be
made available on a fee basis. This can
frequently be accomplished, with the
added bonus that skilled operating personnel
can also be obtained. When the
right location is identified, this can be
an elegant solution to the problem.
A few years ago, INDA organized a
PORTABLE SPECTROSCOPY OFFERS A SOLUTION
TO AN AGE-OLD RESEARCH PROBLEM
Every now and then laboratory scientists are given a problem where they
wished they could take their laboratory into the plant, the customer’s operation,
or some other remote location to study a particular situation. The scientist
has often been convinced that if only they could get the infrared unit or some
other equipment into a particular location, the answer could be easily obtained.
A sizeable step forward in making that wish come true is the advent and
advances associated with portable spectroscopy units. Feature articles in this
Department in previous issues of the International Nonwovens Journal have
dwelt with the advances being made in equipment to assist in identifying plastic
materials slated for recycling efforts. Now, further powerful equipment and capabilities
have advanced beyond, with the development of portable spectrometers
with broad capabilities and even portable FTIR equipment.
The Tristan line of spectroments typifies some of these advances. This particular
product line is the development of an alliance of three German companies
that brought their specific talents together to develop this sophisticated system.
The company m-u-t GmbH brings their engineering and development experience
on R&D operations to the alliance. Photon Technology International Inc (PTI)
has broad experience in spectroscopy, as does PhotoMed GmbH, with special
skills in applications.
Together, the group has developed the portable and versatile Tristan unit, which
can measure absorption, reflection, transmission and fluorescence by measuring
the wavelengths and intensities of light emission. It can rapidly and simultaneously
detect the entire spectral output of light from ultraviolet to the near infrared,
along with an extended-red sensitive version. The unit includes the light sources,
probes, sample handling accessories, optics system, computer for control and
recording of spectra. Developed applications include analysis of ingredients and
raw materials, textile color control, identification of plastics, glass and other recyclates.
A power source allows eight hours of remote operation. (Photon
Technology International, 1009 Lenox Drive, Suite 104, Lawrenceville, NJ
08648; 609-896-0310; Fax: 609-896-0365; www.tristan-home.com)
Portable FTIR technology has been used for a wide variety of analyses, including
organic chemicals, inorganic materials, clays, soils, paints and other coating
materials, petrochemicals, petroleum products, adhesives, plastics and others. An
interesting application that has quite fully exploited the potential of this portable
equipment is in connection with the examination of paintings, sculpture and
other art objects.
In this case, the on-site capabilities, as well as the non-destructive character
and the adaptability to extremely small sample size have been significant advantages.
This has allowed art conservators and experts to authenticate art objects
and also to eliminate fraud and counterfeit items. Further, this technique has
been very useful in examining deterioration and guiding restoration efforts. One
additional interesting use for portable FTIR has been in examining petroglyphs
on stone walls and in caves at some remote archeological sites.
Maybe that difficult problem out in the plant can be studied and solved with
FTIR analysis after all.
INJ Summer 2001 5

RESEARCHER’S TOOLBOX
INTC 2001: A GREAT TOOL FOR BOTH THE
INDA AND TAPPI TECHNICAL COMMUNITY
The 2nd Annual International Nonwovens Technical Conference
(INTC) 2001, co-sponsored by TAPPI & INDA, will be held
September 5-7, 2001 at the Renaissance Harborplace Hotel in Baltimore,
Maryland. Over 80 technical papers will be presented in 14 sessions,
making INTC 2001 one of the largest technical conferences ever in the
nonwovens industry.
Combining the TAPPI Nonwovens and INDA technical conferences
has worked out for the better of the technical nonwovens community. One
example is found in the Properties and Performance session. Norm
Lifshutz will present results on the development of a fiber length test
method conducted in a TAPPI Fiber Length task force, while Mike
Thomason will present INDA test methods on behalf of the INDA Test
Methods Committee.
Other sessions of focus are: Absorbents, Barrier, Binders & Additives,
Filtration, Finishes & Surfaces, Mats & Insulation, On-Line Measurements,
Polymers & Fibers, Properties & Performances, Sustainability, and four sessions
have been devoted to new process technologies.
INTC 2001 will once again offer attendees the nonwoven tutorial
taught by industry veterans, Roy Broughton, of Auburn University, Terry
Young, Procter & Gamble, and Alan Meierhoefer, Ahlstrom Fibers. Other
returning favorites include the Student Paper session, the New
Technologies Showcase and the evening tabletop event and reception.
The six technical committees of the TAPPI Nonwovens Division —
Properties and Performance, Process Technology, Building and Industrial
Mat, Binders and Additives, Polymers and Fibers, and Filtration — will
meet during the lunch sessions on September 5th and 6th.
Written papers are due to INDA by June 26 and presentations in electronic
form are due to TAPPI by August 1.
For conference or registration information regarding INTC 2001, visit
INDA’s website at www.inda.org or call 919-233-1210.
survey of the nonwoven process and
testing equipment available at the major
universities in the US; a report of the
facilities available at that time was prepared.
Material from this report is currently
available at www.inda.org.
With an announcement coming out of
Texas Tech, a new location and their
new process equipment now needs to be
added to this roster. Texas Tech
University in Lubbock, TX has recently
added some advanced needling equipment,
which puts them in a potent position
to become deeply involved in nonwoven
technology. This equipment is
being added to the International Textile
Center at Texas Tech, under the direction
of Dr. Seshadri Ramkumar, Adjunct
Professor at Texas Tech.
The Nonwoven Laboratory at the
International Textile Center will be the
first facility in the U.S. to have this
needling capability. It is based on the
state-of-the-art Fehrer H1 Technology
needlepunch loom. The principle of the
H1 Technology and of this equipment is
the special properties that can be
obtained by oblique angled needle penetration.
This unique capability is
achieved by means of an asymmetrically
curved needling zone, accompanied
by a straight needle movement. Because
of this design, some fibers are punched
or inserted at an angle rather than in a
vertical direction. According to the
design developer, the advantages of this
new technology include the following:
1. The longer needle path results in
better fiber orientation and fiber entanglement
than the conventional needle
machine.
2. Superior web properties can be
obtained with fewer needle penetrations.
3. It greatly enhances the construction
of composite and hybrid products.
4. It delivers increased productivity
versus conventional needlepunch
looms.
The processing line includes units for
complete processing, from bale to finished
fabric. A Tatham Card fitted with
a three-roller/seven-roller design is fed
by a Tatham Single Automatic Feeder,
Model 503; this latter unit is equipped
with a volumetric delivery system. A
Microfeed 2000 unit is included in the
line to monitor the fiber delivery from
the chute section of the volumetric hopper
and to speed of the card feed rollers;
this compensates for any discrepancy
between the pre-programmed “target”
weight and the continuously monitored
“actual” weight. Thus, the Microfeed
unit ensures extremely accurate fiber
delivery into the card unit. The web
from the card is delivered from the single
doffer section of the card to a
Tatham conventional design crosslapper.
The line is equipped with an AC
Inverter-controlled drive system.
A research program focusing on this
new line has been supported by a
research contract from the Soldier and
Biological Chemical Command of the
U.S. Department of Defense. The major
objective of this research program is to
develop special protective fabrics that
can be used by the Command to provide
advanced textile materials to all branches
of the military.
Additional information can be obtained
from Dr. Seshadri S. Ramkumar, Texas Tech
University, International Textile Center, Box
45019, Lubbock, TX 79409; 806-747-3790,
ext. 518; Fax: 806-747-3796; s.ramkumar@ttu.edu;
www.itc.ttu.edu/ram.htm.
— INJ
6 INJ Summer 2001

INJ DEPARTMENTS
DIRECTOR’S
CORNER
Success In Innovation Projects
A research center within the Wharton
School of Business at the University of
Pennsylvania focuses on innovation and
entrepreneurship. The Sol C. Snider
Entrepreneurial Research Center is
staffed with world-renown scholars and
researchers and has done some farreaching
research in the correlation of
innovation with other business and economic
factors.
A recent study was directed toward
the effects on innovation team performance
of three underlying elements of
management organization and operation.
The three elements studied in
detail were as follows:
• Task Structure: The physical organization
of the innovation team.
• Project Framing: Delineation of the
project goals and methodology.
• Team Deftness: Team effectiveness
as assessed by past performance and
other factors.
The study used a total of 138 innovation
projects for analysis, projects in
which the ultimate success and effectiveness
could be quantified.
The results of this study suggested
that the absence of Project Framing in
terms of clearly specified goals and
responsibilities had a negative correlation
with team performance. Clearly
defined goals and clean-cut responsibilities
are critically vital to the innovative
success of the team. Any uncertainly in
these two factors were manifestly operative
in detracting from the performance
of the innovation team.
The factor of “Team Deftness” correlated
with performance of the team, and
also had an impact on Project Framing.
The researchers suggested that this factor
had a moderating effect on the total
performance, and could help to modify
some of the problems associated with
Project Framing. This suggested that
experienced and capable innovators
could overcome, to a certain extent, the
shortcomings of management in not
clearly defining the goals and team
assignments. In essence, the experienced
innovators sensed the need and
filled this missing factor themselves.
The researchers concluded that the
often-assumed positive relations
between organization of the team and
its success is valid, but only for relatively
high levels of organization and on
complex projects.
The message: Organize your team
well; provide very clear-cut objectives
and responsibilities; and use capable
and experienced people on your innovation
team.
Attracting Laboratory Technicians
Some concerted thinking and action
is being devoted to the position of laboratory
technician. In the past, many of
the individuals who are lab technicians
have come into the laboratory without
experience; it often has been the responsibility
of the employer to train such
individuals and to equip them for the
responsibilities they will eventually be
given.
Such “home-grown” talent may have
sufficed in the past. Certainly, some
outstanding people have come up
through the ranks in this fashion. More
than a few patents covering nonwoven
technologies have the name of an outstanding
lab technician as a co-inventor.
However, training of laboratory technicians
is being done more and more by
trade schools, community colleges and
even universities. A capable lab technician
can be a real asset to a R&D establishment.
Consequently, more thought
is being given to the proper training and
development of such talent. The
Partnership for the Advancement of
Chemical Technology recently conducted
a Research Profile Study to assess
the personality traits, attitudes, learning
styles and values of quality lab technicians.
The study, sponsored by the
National Science Foundation, covered
not only such individuals, but also students
studying for such a career, as well
as instructors involved in their training.
The study found these individuals to
be highly collaborative and only moderately
independent or competitive. The
students also tend to be more introverted
than the general class of students,
and they are nontraditional, with many
older than 30.
In focusing on the ideal instruction
for these individuals, the study revealed
that curriculum designers should consider
including group problem-solving
activities and roundtable discussions in
their courses for lab technicians. These
are the skills and environmental features
involved in this type of work, and
so appropriate training should be provided.
Also, the study showed that almost
half of the technician students have a
friend who works in a laboratory or
similar job, suggesting that current lab
workers are a good conduit for getting
the word out to prospective students.
Further, greater efforts should be made
to assure these students that the careers
available put them in a good position to
truly become professional researchers.
R&D Return On Investment
A sizeable portion of the industries
throughout the world would consider
themselves to be a part of a vast
research-driven enterprise. Certainly
those in the nonwovens industry would
consider their activities to fit into this
classification. (Note the message in the
editorial in this issue.)
Such research-driven companies
almost invariably believe or at least pay
lip service to the concept that money
invested in R&D activities provide a
payback. Proof of such a return, however,
is always difficult to establish, espe-
INJ Summer 2001 7

DIRECTOR’S CORNER
cially if inadequate accounting practices
are employed. Too frequently the evidence
is ephemeral, a “gut feeling,” or
anecdotal in nature. Many business
leaders want a more precise and defendable
basis for the annual agonizing decisions
involved in approving the R&D
budget.
Surely the $419 billion chemicals
industry in the U.S. is a research-driven
affair. And yet, even this business segment
struggles with the Return On
Investment for the R&D budget.
Noteworthy is the fact that the chemical
industry portion of the total U.S. R&D
investment has been declining for years,
from 11% in 1956 to about 8% in the
past decade.
The exact reason for this decline is
uncertain; perhaps the percentages are
skewed by the fact that the computer
and related research-oriented industries
have grown so much in the past decade
and chemicals are just a smaller piece of
the whole. Undoubtedly another factor
is that no one has exactly quantified
what kind of bang these companies get
for their research buck.
A new report from the Council for
Chemical Research (CCR) addresses
this problem by analyzing data from
more than 80 publicly traded chemical
companies. From this study the conclusion
was drawn that, on the average,
every dollar invested in chemical R&D
today yields $2 in operating income
over six years. This has apparently confirmed
many of those gut feelings.
In the next phase being pursued by
this program, CCR will evaluate results
from specific types of R&D. It is hoped
this study will lead to techniques, topics
and evidence that will further validate
these concepts. This should materially
help to further sharpen the business
communities view of R&D expenses in
the chemical industry. It is sincerely
hoped that similar forces are acting
within the nonwovens industry.
Getting the Message Out
One of the most difficult responsibilities
for a Research Director is to get out
the numerous messages associated with
MEETING STAFFING NEEDS WITH SENIORS
Although conditions change quite rapidly, there does seem to be continuing
problems with research organizations filling all of their staff needs. The
Research Administrator feels this is especially true when it comes to filling the
empty slots with “good people.”
One potential source that may be overlooked in this search is the labor pool of
older workers and even senior citizens. Of course, most of these slots require
special skills. However, such special skills are not unknown amongst the reservoir
of such older people.
Some universities have done an excellent job with this approach, enlisting the
services of experienced and seasoned professionals. Sometimes the position is
created with a specific individual in mind, perhaps to teach a special course or
assist with a special project. The position of “Adjunct Professor,” “Adjunct
Research Scientist” or similar is often used to designate and exploit such talent.
There are several notable examples of this approach within academe at the present
time, in both the practical as well as the theoretical domain.
However, virtually all levels of technical, scientific and business activities can
be considered for this approach. A second career, even at a lower level and a
somewhat different arena, may be attractive to individuals with talent, skills and
experience. The old wisecrack about the person who retired and then went seeking
a job after six weeks likely has a solid basis in fact.
This is borne out by data from the recent U.S. Census. The number of
Americans 65 and older working or seeking work increased 10% between March
1999 and March 2000 to 4.5 million, the Census Bureau said in a recent report.
These data indicated that there was a 22% increase in seniors in administrative
support positions, including clerical jobs, and an 18% increase in sales job.
The Alliance for Retired Americans, in pointing to these increases, indicates
there are 32.6 million in the age group over 65, 1% more than in the previous
year. Not all of these people want to work, obviously, but an increasing portion
apparently do want to continue to work.
It is interesting that a recent Wall Street Journal article (May 23, 2001)
described an effort by the American Association of Retired People. This organization
wanted to select the “Best employers for workers over 50.” They mailed
invitations to 10,000 companies to provide information to assist in the selection.
Only 14 companies responded!
Many companies indicated they had not given that aspect of their Human
Resources efforts any consideration. It seemed to be an area where the average
employer was largely out of step with the aging of the work force.
There are some companies that are exceptions, of course; they obviously are
exceptional. At CVS drugstore chain, for example, 15% of the employees are
over 55; CVS actively recruits older workers. It says they stay with the company
longer and show more commitment.
There are obstacles to some of these practices, including phased-retirement,
where an employee goes from a full-time status to employment that is less than
full-time. Some of the obstacles are related to retirement, taxation, pension benefits,
etc. These obstacles may require federal legislation to correct. Working conditions,
flexibility and a desire for autonomy may be other factors to consider.
Overall, however, this is an employee pool that will receive more consideration
by managers in the future. After all, during the year of 2001, the number of
workers who are 40 and above will surpass those under 40 for the first time.
Good Hunting!!
8 INJ Summer 2001

DIRECTOR’S CORNER
safety, accident prevention, pollution
control and the like. It is a task that is
never finished; it has so many aspects,
and yet can be critically important,
especially in retrospect following an
“event.”
Pity the plight of the poor Safety
Manager/Industrial Hygienist/Environmental
Manager who must deal with
such motivational things all the time.
The problem is to continuously get
the messages out to all personnel, get
them to read or study the materials at
regular intervals, and then repeat and
reinforce the messages unceasingly.
That’s quite a challenge.
One enterprising Safety and Hygiene
officer within the Procter & Gamble
organization chose a rather unusual
approach that has proved to be quite
effective. He acknowledges that he did
not get prior management approval for
the technique, undoubtedly because he
was rather confident that such approval
would not be forthcoming. Nevertheless,
he moved ahead with determination
by regularly posting his safety messages
in the bathroom stalls at the P&G
Health Care Research Center in Mason,
Ohio. To ensure sufficient time for the
entire message to be read and studied,
the postings were made adjacent to the
toilet commode, where they would be
easily available to every occupant.
The safety-related items were soon
referred to as “potty postings,” also
called “toilet tabloids.” The manager
confessed that there was a certain
amount of resistance to the approach at
first, but the message was getting out!
One associate complained that “Our last
bit of privacy is being invaded by safety
messages!” Another asked the question,
“Is no place sacred?”
Undaunted, Allan Bayless, the Safety
Manager, persevered in the program and
was rewarded within a few weeks when
the grousing subsided and some positive
comments began to emerge. He reported
that some colleagues even began to
offer suggestions and to request new
postings if the current ones stayed up
too long.
He now has management approval,
and reports that the approach is being
tried at other P&G locations. His experience
has shown that popular topics
include a range of rather violent events.
Apparently everyone loves an accident,
a flood, a fire or a reaction gone crazy.
He always tries to exploit the described
event by discussing what went wrong
and what should be done to correct the
situation. Bayless found this approach
to be much more effective than simple
e-mailing individuals. After all, an e-
mail can be discarded with a key stroke!
If this approach sounds useful and
further information in desired, Bayless
can be contacted via e-mail at
bayless.av@pg.com.
An Environmental Policy
The peoples of this earth have come a
long way in developing an environmental
conscience and doing the “right
thing.” The past 40 years have seen a
large portion of the population grow
from disinterest into a strong concern for
the world’s environment and the legacy
that will pass to future generations.
The effort has had its distracters of
course. On the one side there have been
the adamant resisters and the obscene
polluters. On the other side have been
the eco-extremists and eco-thugs.
Despite this situation, progress has been
achieved.
An interesting policy statement on the
environment and their relationship to it
has recently come from one of the nonwoven
industry’s major members —
J.W. Suominen Oy, Nakkila, Finland.
While Suominen’s Environmental
Policy statement is simple and straightforward,
it clearly provides a basis for
decisions both large and small. It can be
readily understood by top management,
board members, middle managers and
employees at all levels, as well as by
customers, competitors and the general
public. It would seem that all sectors of
the industry would benefit from a similar,
simple statement or credo that
would guide all phases of a company’s
operations.
An example of Suominen’s
Environmental Policy statement appears
ENVIRONMENTAL POLICY
J.W. Suominen develops, produces
and supplies nonwovens profitably
according to customers’ needs, such
that the activity’s adverse environmental
impacts are as slight as possible.
JWS’s key environmental aspects are:
• Prevention of pollution.
• Continual improvement so that
environmental loading, in relation to
production volume, decreases annually.
• Environmental loading is monitored
and measured comprehensively
and the results are public.
in the box on this page.
To decrease environmental loading,
JWS uses BATNEEC (Best Available
Technology Not Entailing Excessive
Costs), minimizes the waste and recycles
where feasible. JWS commits to
fulfill relevant environmental legislation,
regulations and other obligations.
Top management establishes the environmental
objectives and appropriate
resources for their implementation and
monitors their performance.
Supervisors are responsible for implementation
of environmental targets
related to their area of responsibility and
continually aim to consider the
improvement of environmental performance
while developing activities and
working practices.
Personnel’s commitment, as well as
the recognition of their own responsibility,
is ensured by systematic training,
communication and encouragement.
While it may not be perfect, it is concise
and understandable! — INJ
INJ Summer 2001 9

INJ DEPARTMENTS
TECHNOLOGY
WATCH
Tracing Water Pollution Sources
In the past, water polluters have benefitted
from the fact that water pollution can be
clearly identified, but the source of pollution
is much more difficult. That situation
may be changing somewhat, with the
advent of a DNA “fingerprinting” test to
trace the source of water pollution.
This test, which was developed at the
University of Missouri-Columbia, is based
on tracing the water pollution back to its
sources by using the DNA from bacteria.
The presence of fecal E. coli bacteria —
microbes that live in the intestines of their
host until they are excreted — commonly
is employed to establish if the pollution is
due to human or animal wastes. While
these organisms of themselves are nonpathogenic,
their presence in a water gives
a warning of the potential presence of other
disease-producing strains of E. coli, salmonella
or hepatitis virus that can also be
found in human and animal waste.
The method utilizes a technique known
as DNA pattern recognition, or ribotyping.
This novel approach takes advantage of the
fact that each host species harbors specific
types of E. coli in the intestinal tract that
have specific DNA patterns, or “fingerprints.”
The DNA results are then compared
to known DNA patterns from known
host species. This then gives an indication
of possible sources of the contamination.
At the present time, the method can be
used to clearly identify contamination
coming from eight common hosts:
humans, cows, pigs, horses, dogs, chickens,
turkeys and migratory geese. Further
work is being carried out to expand the
DNA database of hosts and to further
refine the technique to identifying characteristics
of pollution sources. Current
chemical analysis, of course, can provide
very precise information on the presence of
organic and inorganic pollutants; these
dates, coupled with water flow and movement
patterns, can generally pinpoint the
sources with convincing results.
Active Antibacterials
The use of antibacterial agents in a host
of consumer, medical and industrial products
has exploded in the past few years.
Seven times as many antibacterial products
were produced in 1998 than in 1992.
Antibacterial finish has become the standard
finish in some textile product categories.
Nonwoven products have participated
in this action is a significant way,
especially in nonwoven wipes.
The practice has become sufficiently
widespread that consideration has been
given to legislation to stiffen controls on
the use of such materials. Some warnings
have been put forth by the medical profession,
arising from the concern that such
materials can kill beneficial germs as well
as deleterious ones. Also, there is concern
that resistance to such agents can develop
and could lead to a range of super-germs.
Despite such concerns, the use of these
agents is proliferating.
Most such agents act by leaching from
the material to which they are originally
applied, and then contact the microorganisms
and kill them by such contact. These
are the “leaching” type agents.
Their effectiveness diminishes as the
leaching continues, of course, and the
leaching can lead to excessive skin contact
or even to the crossing of the skin barrier;
such behavior can lead to a variety of
problems.
Another class of antibacterial agents is
actually bound to the substrate by molecular
or other forces. Such “bound” materials
usually have hydrophilic or other
groups in the molecule which can penetrate
the microorganism, allowing quaternary
ammonium groups or other groups
to rupture the organism’s cell wall, leading
to expiration. This bound type of
material can kill when the organism
resides on the substrate; hence, it is more
limited in scope.
An interesting class of durable agents
was recently described with the added
feature of being capable of regeneration
of the active chemical moiety. In this
agent, one functional group is used to
attach the molecule permanently to cellulose
fiber via a molecular bond. The functional
group also contains a cyclic hydantoin
group, which can be easily chlorinated
to form the reactive cyclic chlorohydantoin
group. This latter group is an
effective disinfecting agent that is widely
used in swimming pools and other similar
applications. As the disinfecting
action continues, the chloro-group is converted
back into the unsubstituted hydantoin
group. This latter group can be easily
converted back into the active chlorohydantoin
form; such chlorination can be
done simply by treating the fabric with a
chlorine bleach. Hence, the regenerable
feature.
Very recently a special polymer has
been developed at Massachusetts
Institute of Technology that is claimed
to have special germicidal properties.
When the polymer is coated onto a hard
surface, the developers claim that it is
there permanently and can guard against
infections commonly spread by sneezes
and dirty hands. The materials is
described as hexyl-PVP (PVP-polyvinyl
pyridine).
The PVP portion has been known to be
active in solution, but attempts to immobilize
the material on a surface seemed to
render the polymers totally inactive. The
researchers found that the addition of the
alkyl chain (3-6 carbon atoms) eliminated
the inactivation. It is claimed that this
material in a coating form is able to kill up
to 99% of Staphylococcus, Pseudomonas,
and E. coli, all common disease-causing
organisms. The killing action is stated to
be via a powerful chemical-electrical
action. The researchers have hypothesized
that the addition of the polymer side chain
of the right length provides flexibility for
the coating material to penetrate the bacterial
cell wall envelope on contact and do
its job. These are the first engineered surfaces
that have been shown to kill airborne
microbes in the absence of any liquid
medium. This work suggests a new
possible approach to engineer a solid surface
to provide bacteria-killing action.
The major markets for most types of
10 INJ Summer 2001

TECHNOLOGY WATCH
biocides is for water treatment, paint protection,
wood preservation and similar
applications. Use in textile and fiber materials
is significant, however, and is continuing
at a fast pace.
Another somewhat related development
in chemical/biological activity of
textile fibers concerns cotton wipes that
can be used to decontaminate nerve
agents on contact. This work involves
covalently linking an enzyme to cotton
fiber. The enzyme, organophosphorus
hydroxylase from Pseudomonas diminuta,
is the only enzyme known to detoxify
a wide range of nerve agents. The modified
fabric rapidly hydrolyzes the agent
Paraoxan (a nitrophenyl ester), indicating
the immobilized enzyme retains it activities.
The fabric can also convert the infamous
nerve gas, Sarin, along with others,
as well as the toxic insecticides parathion
and methylparathion, to harmless byproducts.
The fabric doesn’t irritate
human skin and retains 70% of its original
enzyme activity after two months, either
refrigerated or stored at room temperature.
Modified fibers and fabrics can obviously
be made to do wondrous feats.
More Chemical Scares
A recent action by a government-sponsored
panel of scientists and environmentalists
has the potential of creating a superabundance
of chemical scares in the future.
If the course outlined by this panel is following,
research administrators are in for a
rough ride ahead.
The problem centers around a report by
a National Toxicology Program panel,
which concluded in May, 2001, that some
chemicals can affect laboratory animals at
very low levels, well below the “no effect”
levels.
This rather shocking, self-contradictory
conclusion violates a fundamental principle
of toxicology — namely that “the dose
makes the poison.” This principle asserts
that all substances can act as poisons in sufficiently
high amounts, even such benign
substances as water, sugar and salt; you
name it. However, below their “toxic
doses,” such substances are considered not
to be poisons.
The government panel concluded that
there is “credible evidence” of the effect of
some chemicals on laboratory animals at
such very low levels. The evidence seems
to flow from concern with so-called
SYNTHETIC PAPER SHOWING EXCEPTIONAL GROWTH
Originally introduced into Japan several years ago, synthetic paper is starting
to show exceptional growth in a variety of markets and applications.
This product consists of thin plastic sheet material containing a filler or a special
coating to give it the printing characteristics of conventional paper. The base
for a synthetic paper may be polyethylene, polypropylene, polystyrene or polyethylene
terephthalate; suitable fillers are titanium dioxide, calcium carbonate or
various silicas. typical paper coatings based on clay, calcium carbonate or other
materials can be employed to provide a good printing surface.
The growth of this type of material is expected to be in excess of 8% per year,
from a current base of about $200 million; this will result in a 166 million pound
market by the year 2005, according to one recent study.
The use in specialty label applications is the largest current market for these
materials. However, it is anticipated that growth in other related markets will
exceed the growth in labels; these other market applications include commercial
printed products, such as greeting cards, menus, maps, books and covers, signage
and point-of-purchase displays. In the label market segment, significant applications
include pressure sensitive labels, in-mold labels, and unsupported tags.
At the present time major producers include: PPG, Oji Paper (Japan) through
their subsidiary Yupo, Nan Ya Plastics, ExxonMobil, and Arjobex (a three-way
joint venture of BP, Arjo Wiggins (London), and Appleton Papers). Some of
these properties and markets suggest possible usage of nonwoven materials.
endocrine disruptors, also referred to as
environmental estrogens. These materials
are described as hormone-like chemicals in
the environment that can disrupt normal
hormonal processes and cause everything
from cancer to reproductive problems to
attention-deficit disorder.
The public concern with these possibilities
began with claims based on
research work by the University of
Missouri researcher Frederick vom Saal
and a book he published, entitled “Our
Stolen Future.” He carried out experiments
on laboratory mice that purportedly
showed that very low doses of some
chemicals increased prostrate weight in
male mice and advanced puberty in
female mice. The doses employed were
thousands of times lower than current
safe standards.
Reportedly, no other laboratory has been
able to reproduce vom Saal’s work; reproducibility
of experiments is necessary, of
course, before a conclusion can be accepted.
However, vom Saal all but guaranteed
that his work will never be reproduced. His
experiments involved a unique strain of
mice that he inbred in his laboratory for
about 20 years. When the mice stopped
producing the results he wanted, he killed
them.
However, the results he promoted were
embraced by others who felt they matched
their environmental and political agenda.
The panel given the assignment to assess
this situation was apparently loaded with
such individuals.
In any event, the panel recommended
that the EPA consider changing its guidelines
for assessing risk of reproductive and
developmental effects from chemicals.
According to some experts this recommendation
is likely to spread to other
national and international regulatory agencies.
The low-dose theory could put virtually
every industrial chemical and many consumer
products at risk of being stringently
regulated or banned without a scientific
basis. This development bears watching by
anyone concerned with chemicals and
products. Further information can be
obtained at several websites, including
www.junkscience.com. — INJ
INJ Summer 2001 11

INJ DEPARTMENTS
THE NONWOVEN
WEB
12 INJ Summer 2001
Distance Learning
It used to be that a remote location precluded
a number of activities for a person
who was so unfortunate. An opportunity
to study and continue one’s education
was certainly one of those factors
that had to be sacrificed. No More!!!
If the men and women serving in the
U.S. Navy aboard a ship at sea anywhere
in the world can continue their graduate
education, location is no longer an insurmountable
barrier. The solution is what
is referred to as “Distance Learning.”
That is not learning about how far “far”
is, but rather it signifies learning that can
be done at virtually any distance from
the source of the teaching.
A growing number of universities and
colleges are beginning to offer an
expanding selection of courses that are
presented via the Internet. This arrangement
is not the same as a correspondence
course, as the student can virtually be
present in the usual class setting and
have direct and instantaneous contact
with the instructor and fellow students,
all by means of a computer terminal and
a communications link.
Many universities are working to convert
their classroom materials into a form
most suitable for this medium.
Professors and teachers are learning how
the usual teaching methods can be most
effectively converted into the cyberspace
classroom. Some adaptation of methods
and materials must be made, of course,
but the transition is being mastered.
At the government level, the Small
Business Administration (SBA) has
introduced the new SBA Small Business
Classroom, which brings electronic business
courses to anyone with a standard
Internet connection. This virtual classroom
provides interactive, easily accessible
courses on the topics most in demand
by small-business owners. Typical classes
include: “The Business Plan” (in
English and Spanish) or “How to Raise
Capital For a Small Business.” At the end
of each lesson, students can participate in
a scheduled chat room, or call a toll-free
number to talk with a counselor
(www.sba.gov and then select SBA
Classroom).
Not a part of Distance Learning, there
were recent press reports on several campuses
involving enterprising students
putting today’s lecture notes on the web
for the benefit of friends who missed the
class. Some professors objected strenuously
to this practice, even claiming that
notes from their lectures were akin to
copyrighted material. In direct contrast
to that attitude is the recent announcement
by Massachusetts Institute of
Technology (MIT) that over the next 10
years, the university will post materials
for almost all of its courses on the World
Wide Web, accessible to one and all at no
charge. Materials posted will include
course outlines, reading lists, lecture
notes and assignments.
As ambitious as this approach is (estimated
cost is $10 million per year), it is
probably not the same as getting an MIT
education for free. Unlike Distance
Learning programs, which involve regular
exchanges between faculty and students,
there will be no course credit or
degrees offered to people who access
Open-CourseWare, as it is being called.
Nevertheless, the early response to the
MIT move has been very positive. Not
only in developing countries, but in
advanced nations as well the benefits of
Distance Learning are being appreciated
and used. This activity will undoubtedly
further increase concern with the
“Digital Divide,” which separates those
who do not have access to the Internet
from those who do.
Some professional societies are
becoming involved in the process. The
Society of Dyers and Colourists in the
UK has presented a Distance Learning
module on “Principles of Engineering”
and “Coloration Theory.” Future plans
call for additional modules on Color
Physics, Colorant and Polymer
Chemistry, Coloration Technology, and
Organization and Management.
Within the nonwoven technology sector
some steps in this direction have been
SPAM VS. spam
Even a novice on the Internet is familiar with the junk E-mail that virtually
abounds on the net and goes under the name of “spam.” Such unsolicited
mail is a fact of life on the Internet and it is a rare netizen who hasn’t experienced
it.
On the other hand, there is a well-known spiced lunch meat made of pork
shoulders and ham that is known worldwide, and considered a choice delicacy in
many parts of the world. This product of Hormel Foods Corporation goes by a
brand name that is considered a very valuable piece of intellectual property —
“SPAM” registered trade mark for the meat product.
For several years Hormel fought against the use of the word “spam” to designate
the wrong kind of e-mail. They worked diligently to protect their name and
to police the mounting misuses. After this valiant effort, the company has finally
acquiesced to a compromise, as outlined on their official SPAM website
(www.spam.com/ci/ci-in.html). Hormel says it no longer objects to that other
designation, as long as it is spelled in small letters — spam, that is. However, for
this concession, they expect their trademarked product to be spelled in capital
letters — SPAM brand of meat product.
Seems like a reasonable compromise.

THE NONWOVEN WEB
made and more are being taken. Access
to specific nonwoven technology training
is becoming available from some universities.
Problems still exist, such as the
matter of oversight and quality control,
as expressed by some committees within
various universities. Also, there is the
question of the more subtle interactions
between student and teacher which naturally
arise from questions and answers,
and by other means.
However, as more experience is
gained, the processes will undoubtedly
improve. After all, a telephone call to a
colleague can be a form of Distance
Learning.
Electronic Signatures
The electronic signature law went into
effect in June of 2000. This law gives
digitally signed documents the same
legal weight as those with physical signatures.
In essence, this allows a person
to simply click a box and accomplish the
same results as signing a document with
pen and ink.
It may come as no surprise, however,
to learn that individuals and companies
have been slow to stamp their signature
on business transactions via electronic
means. Even with companies that could
use this method to a great extent, such as
financial services and legal firms, there
has been a reluctance to use the method.
One roadblock to the acceptance of
electronic signatures is obviously the
problem with the ability to verify the
signer’s identity in court. It is rather difficult
for an individual to deny a signature
when it is there in ink on a document;
it is considerably easier to deny it
when done by an electronic keystroke,
especially if there was no one around at
the time.
There have been attempts to use
advanced technology to eliminate this
factor, and companies are offering security
means to eliminate this uncertainty.
Unfortunately, these means are rather
expensive, especially for a single or only
a few signatures.
Where there are repetitive transactions
between two companies that have a continuing
relationship, or transactions within
a small, closed trading community, the
concept may be very viable.
Some of these problems are very similar
to those encountered on the Internet,
where a great deal of effort has been
expended to establish secure boundaries
around business transactions. Anonymity
is an inherent feature of the net and electronic
space. This characteristic is
acceptable for some interactions, but certainly
not for others. For now, most companies
are taking a “wait-and-see” attitude
toward the electronic signature.
Sci/Tech Web Awards 2001
One of the very interesting websites on
the Internet is that of the science journal,
Scientific American (www.scientificamerican.com).
The site provides a
Table of Contents of current and past
issues, and even posts the full text of
some of the articles.
The publication also conducts an annual
search of scientific sites and selects
five sites from 10 different categories to
receive their “Sci/Tech Web Award
2001.” The sites are selected for a variety
of reasons, as the selections are “an
eclectic mix — from the practical to the
academic to the downright silly.”
The categories covered by their search
include Archaeology and Paleontology;
Earth and Environment; Astronomy and
Astrophysics; Engineering and
Technology; Biology; Mathematics;
Chemistry; Medicine; Computer
Science; and Physics
Some very interesting websites arise
from the list of their selections. There is
a site that gives a listing of a vast number
of acronyms, listed alphabetically or by
topic, along with definitions for thousands
of the most current IT-related
words (www.whatis.com). The medical
category has an online version of the
classic reference book, Gray’s Anatomy,
with 1,247 engravings from the original
1918 publication (www.bartleby.com).
The Engineering and Technology category
offers an interesting web page that
highlights bad product designs resulting
in items that are hard to use because they
do not follow human factors principles
(www.baddesigns.com ).
The variety in the sites selected for the
award gives an appreciation of the diversity
of material that is posted on the web.
Computer Viruses
A new version of the computer virus
has struck the Internet. This recent virus,
called “sulfnbk,” doesn’t do much harm
to your system, but it sends you on a wild
goose chase to find and eradicate an
obscure and innocuous utility file (sulfnbk.exe)
in Windows 98/Me before a supposed
expiration/explosion date.
When dealing with such matters, it is
very helpful to be able to call on some
expert advice and help. Again, the
Internet comes up with the answer. One
source of such assistance is a computer
information resource (www.geek.com).
This site has a variety of useful information,
including a consumer warning area
that can be of real help in a situation of
this type.
Also, another site can be a useful
resource when it comes to “computer
virus myths, hoaxes, urban legends, hysteria”
and such. This site
(www.vmyths.com) is dedicated to providing
the truth about computer virus
myths and hoaxes. This site includes
information on new viruses as well as old
ones, as it points out that “Old hoaxes
never die, they just get a new life cycle.”
Relatively New Stuff
This phrase is the byword for a website
that is an online marketplace for used and
discounted scientific equipment. The site
(www.einsteinsgarage.com) offers used
and still-in-the-box, brand-name instruments,
equipment, supplies, chemicals,
safety apparatus, protective clothing,
teaching aids and more. Their motto is
“The theory of relatively new stuff,” a
take-off from the original Einstein.
The items offered cover a range of
products from well-known equipment
manufacturers. They are offered on an
auction basis, although users can sell,
auction and advertise surplus equipment
as well. Einsteinsgarage is a
member of Alchematrix, a wholly
owned e-commerce subsidiary of
Fisher Scientific.
— INJ
INJ Summer 2001 13

ORIGINAL PAPER/PEER-REVIEWED
Wet Process Drainage — Effects of
White Water Chemistry and
Forming Wire Structures
By Daojie Dong*, Senior Scientist, Owens Corning Science & Technology Center,
Granville, OH 43023
Abstract
This paper reports the effects of white water characteristics
and forming wire parameters on wet process drainage. By
employing a recently developed lab tester, the present investigation
conducted drainage experiments of long (32 mm)
fiberglass in polyacrylamide (PAM)-based white water with a
real (commercial) forming fabric in position. The forming
wires under investigation cover air permeability from 465 to
715 CFM and drainage index from 9.5 to 22.
Drainage experiments show that both PAM concentration
and shearing (mixing) effect can strongly affect wet process
drainage. So, white water of fixed composition, but with a different
mixing history may behave very differently, and an
increase in input mixing energy usually results in a substantial
increase in drainage.
Mat basis weight also strongly influences wet process
drainage. Although an increase in basis weight always reduces
the rate of drainage regardless of wire structure, its impact is
much stronger on the wires with a high air permeability and a
low drainage index than the ones with a low air permeability
and a high drainage index.
Another important finding of this study was that drainage
index did not predict the performance of a forming wire, and
the main causes were believed to be the fundamental differences
between the wet-formed glass mat (WFGM) and
papermaking processes. Also, correlation between air permeability
and wet process drainage was found very complex:
while air permeability may be used as an empirical parameter
to predict drainage for light weight mats at low PAM concentrations,
however, the higher the web basis weight and the
higher the PAM concentration, the more likely it would fail.
Key Words
* The author is currently a Senior Engineer with Decillion,
LLC, Granville, Ohio
Wet process, drainage, forming wire, drainage index, air
permeability, polyacrylamide, basis weight, shearing effect
Introduction
Drainage is one of the critical process variables in a wet
process (the wet-formed glass mat process or the WFGM
process). Wet process uses higher viscosity white water and
operates at low slurry consistencies. Its drainage operation is
usually more challenging than in a typical papermaking
process, which is the primary reason that an inclined delta former,
instead of a Fourdrinier machine, is normally used in a
wet process to dewater fiberglass slurries.
Wet process drainage is a complex process depending on
both the physical characteristics of a fiber slurry and the
detailed structure of a forming fabric. The slurry characteristics
encompass fiber content, fiber length and diameter, and
white water chemistry, etc. The wire parameters may include
at least air permeability and drainage index, etc. Since
drainage has great influence on both the sheet properties [1-4]
and the mill performance, the paper industry has consistently
devoted a great deal of resources to gain fundamental understandings
in this area [5-12]. Several experimental methods [6,
13, 14] have been developed to measure the drainage, or freeness,
of papermaking furnishes, among which the Canadian
Standard Freeness (CSF) test [14] is the most common one.
Though various lab drainage testers have been successfully
used to characterize the drainage characteristics of papermaking
furnishes, they are generally not applicable to the fiberglass
slurries used in a wet process [15]. It is also worth noting
that these lab drainage testers are limited to estimate only
the drainage characteristics of furnishes and are not capable of
evaluating the effects of forming wire parameters [15]. In reality,
a drainage process is controlled by the combination of
white water characteristics and the parameters of a forming
fabric. Therefore, it would be very important to measure the
drainage rate under the combined conditions of all these para-
14 INJ Summer 2001

meters.
Recently, a wet process mimic device (WPMD) has been
developed at the Owens Corning Science and Technology
Center that is capable of measuring the drainage rate of wet
process slurries with real (commercial) forming fabrics in
position. The detailed information about the WPMD structure
and developmental work can be found elsewhere [15].
In the present investigation, the WPMD was used as a tool
to study the effects of both fiberglass slurry characteristics and
forming wire parameters on wet process drainage. The rate of
drainage was measured under a simulated line speed and correlated
to various parameters, such as, PAM concentration of
white water, mixing effect, web basis weight, fabric air permeability
and wire drainage index. The approaches used were
very practical, and the reported results are expected to have
close correlation to real wet process operations. Theoretical
modeling of the drainage process is out of the scope of this
paper, but might be addressed in the future.
Experimental
Apparatus
Drainage experiments were carried out using a wet process
mimic device (WPMD) as shown in Figure 1. The detailed
structure and operation procedures of the WPMD were reported
elsewhere [15]. Briefly, the WPMD consists of three stainless
steel chambers and two functional blocks, the drainage
functional block (DFB) and the fiber bleed-through functional
block (FBTFB). As shown in Figure 1, the three chambers are
vertically arranged to create a gravitational flow field. The
DFB block is positioned in between the top and middle chambers,
while the FBTFB block connects the middle and bottom
chambers together.
The DFB, the heart of this tester, is primarily composed of
Figure 1
WET PROCESS MIMIC DEVICE
(1) a gate (or shutter),
(2) a piece of
20 X 20 inch (51
X 51 cm) forming
fabric mounted on
a holder, (3) a
movable “forming
bed” (MFB) consisting
of a series
of supporting bars,
(4) a driving and
control system that
controls the movement
and speed of
the MFB, and (5) a
flow control system
that provides
initial settings for
drainage experiments.
With forming wire
A (as defined in
Table 1) in position,
the reported
Table 1
FORMING WIRE SPECIFICATIONS
Wire ID A B C
Mesh (top) 56 X 26 65 X 52 107 X 54
Mesh (bottom) 65 X 38 107 X 28
Layers 2 2.5 2.5
Caliper (inches) 0.080 0.075 0.0435
FSI 36.0 48.4 86.0
AP(s) (CFM) 750 660 490
DI(s) 10.0 18.6 22.2
AP (CFM) 715 630 465
DI 9.5 17.8 21.1
WPMD has a maximum pure water drainage rate of about 145
gallons per minute per square foot of forming area (gpm/ft 2 ) in
a gravitational field. In the present work, drainage experiments
were not carried out at its maximum capability. Instead, a set
of parameters on the WPMD were chosen so that wire A provided
a pure water drainage rate of ~85 gpm/ft 2 . The rest of
experiments were all conducted under these fixed conditions.
Forming Wires
As reported earlier [15], one of the special features of this
WPMD lies in its capabilities of measuring drainage rate using
real (commercial) forming fabrics. In the present study, three
commercial forming wires were selected (from three different
suppliers) and some of the wire parameters were summarized
in Table 1. These wires have similar structures and all fall in
the double layer category. But, their meshes, strand diameters
and weaving patterns are very different from each other.
In Table 1, the fiber support index (FSI) and caliper data were
obtained from respective wire manufacturers. The AP(s) and
the DI(s) are the specified air permeability in cubic feet per
minute per square foot (CFM) and the specified drainage index,
respectively. The wire samples were measured for air permeability
at the Owens Corning Science and Technology Center
before testing and the results were 715, 630 and 465CFM for
wires A, B and C, respectively. Due to the changes in air permeability
value, the corresponding drainage indexes were
recalculated as 9.5, 17.8 and 21.1, respectively. In the section of
Results and Discussion, the measured air permeability (AP)
and the recalculated drainage index (DI), the data in the last two
rows of Table 1, were used to correlate to drainage.
To study the effect of wire parameters on drainage rate, 20
X 20 inch wire samples were installed into the DFB block for
drainage testing, and all the comparisons were made under
identical experimental conditions.
Materials
Drainage experiments were conducted with Owens Corning
786M 1.25 inch fiber, Cytec Superfloc A1885, and Rhone-
Poulenc Rhodameen VP-532 SPB. The 786M is a chemically
sized fiberglass with a mean diameter of 16 microns. The
Superfloc A1885 is an anionic, high molecular weight polyacrylamide
(PAM) and functions as a viscosity modifier. The
INJ Summer 2001 15

Rhodameen VP-532 SPB is an ethoxylated fatty amine, a surface
active molecule, and functions as a dispersant. In addition,
a small amount of defoamer was also used to control
foam and assist the experiments.
Drainage
It is known that the PAM viscosity modifier is sensitive to a
shearing effect. The received PAM was first diluted to 0.5
wt.% and agitated for 30 minutes. The same batch of diluted
PAM was used for the entire experimental work to avoid possible
variations in raw material and in dilution procedure.
The drainage volume was fixed as 20 gallons (of pure water,
or white water, or fiber slurry). For white water (without
fibers) testing, 20 gallons of water was fed into the top chamber,
followed by a predetermined amount of PAM and 5 drops
of defoamer. The formulated white water was then agitated
under specified experimental conditions before drainage.
A two step procedure, similar to a thick-thin stock procedure,
was used in the preparation of fiberglass slurries. First,
10 gallons of water were charged into the top chamber, followed
by 10 drops of dispersant and 5 drops of defoamer.
Then, the mixer (agitator) was turned on and a pre-weighed
amount of fiberglass was added immediately. In the meantime,
a timer was started to record mixing time. After one
minute of mixing, a predetermined amount of PAM was
added, and additional water was fed to make up a total volume
of 20 gallons.
While the slurry (or white water) being prepared, the movable
forming bed (MFB) was set in motion at a desired speed, and
other drainage parameters were also set at desired values. When
the slurry was ready for testing, the gate (or shutter) was opened
instantly and the drainage process began. The time duration of
drainage was recorded and the average drainage rate was calculated
based on the known parameters of the WPMD. In this
work, a unit of gallons per minute per square foot forming area
(gpm/ft 2 ) was selected for the rate of drainage.
A dual-propeller mixer driven by an air motor was
employed for agitation. The mixer was positioned at the center
of the chamber with its lower and higher propellers 2 3/8”
(6 cm) and 11 5/8” (29.5 cm) above the top surface of the
forming fabric. The mixing (shearing) effect was controlled by
the inlet pressure of compressed air to the air motor.
Figure 2
EFFECT OF PAM CONCENTRATION ON
WHITE WATER DRAINAGE
rate of pure water was ~83 gpm/ft 2 , and the presence of 66 and
165 ppm PAM has reduced the drainage rate by ~35% and
55%, respectively. For wire C, the presence of 66 and 165 ppm
PAM has reduced the drainage rate of pure water by ~50% and
74%, respectively.
The presence of PAM also significantly reduced the
drainage rate of fiberglass slurries as shown in Figure 3. The
nine data points used in the figure had a same consistency of
0.012%, and each slurry was agitated for 5 minutes with a
pressure setting of 28 psig on the driving air motor.
Interestingly, the three wires responded similarly to the changes
in PAM concentration. The drainage rate dropped sharply when
the PAM concentration was increased from 10 to 65 ppm. As the
PAM concentration was further raised to 165 ppm, the drainage
rate continued decreasing, but with a much lower slope.
Basis Weight
Figure 3
EFFECT OF PAM CONCENTRATION ON
FIBERGLASS SLURRY DRAINAGE
Viscosity
White water viscosity was measured with a Brookfield
Model DV-II+ viscometer.
Results and Discussion
PAM Effect
Figure 2 shows the influence of polyacrylamide concentration
on the drainage of white water (without fibers). All the
white waters used in Figure 2 were mixed for 5 minutes with
a compressed air setting of 28 psig. So, PAM concentration
was the only variable, which ranged from 0 to 165 ppm with
“0” representing pure water.
As indicated in Figure 2, the presence of PAM significantly
reduced the rate of drainage. For wires A and B, the drainage
16 INJ Summer 2001

Gravity drainage, in essence, is a filtration process with the
pressure defined by the gravity head of suspension over a
formed web [9] supported on the forming wire. It is obvious
that the web thickness and its degree of compression will
affect the rate of drainage. Since the primary focus of this
paper is to deal with the practical aspects of drainage in wet
process, the web effect on drainage rate was treated with
respect to mat basis weight in pounds per hundred square feet
(pounds/CSF).
Three consistency values of 0.008%, 0.012% and 0.018%
were purposely designed to study the web effect on drainage
rate. These values, based on the particular parameters of the
WPMD, correspond to the formed webs with “fiber basis
weight” of 0.81, 1.30 and 1.86 pounds per hundred square feet
(pounds/CSF), respectively. If a 19% of loss on ignition (LOI),
a typical number for fiberglass roofing mats, is also accounted
for, the three consistency values would correspond to the finished
wet process mats with basis weight of 1.00, 1.60 and
2.30 pounds/CSF. In Figures 4 and 5, drainage rate was plotted
with respect to mat basis weight for the convenience of
readers in the nonwovens industry. The fiberglass slurries used
in Figure 4 were all prepared at a fixed PAM concentration of
165 ppm, and in Figure 5 at a fixed PAM concentration of 66
ppm.
As indicated in Figures 4 and. 5, the rate of drainage was
reduced as the basis weight was increased from 1.0 to 1.60 and
2.30 pounds/CSF. However, the degrees of change were different
among the three wires. For example, at a fixed PAM
concentration of 165 ppm (Figure 4), the drainage line for
wire A has the highest slope, the line for wire B is less steep,
and the line for wire C has the lowest slope. As a result, wire
B has reached comparable drainage rates to wire A at basis
weights above 1.60 pounds/CSF, though its rate of drainage
was ~20% lower than wire A at a basis weight of 1.0
pounds/CSF. Figure 4 also indicated that the difference in
drainage rate between wire C and the others was gradually
Figure 4
EFFECT OF BASIS WEIGHT ON DRAINAGE RATE
(PAM = 165 PPM, DISPERSANT = 2 PPM,
AND DEFOAMER = 1 PPM)
Figure 5
EFFECT OF BASIS WEIGHT ON DRAINAGE RATE
(PAM = 66 PPM, DISPERSANT = 2 PPM,
AND DEFOAMER = 1 PPM)
reduced as the increase in mat basis weight.
At a fixed PAM concentration of 66 ppm (Figure 5), the
same trend seemed to hold. Wires A and B had similar
drainage rates at all three basis weights. Wire C, again, never
reached comparable drainage rates to wires A and B, though
the difference was gradually reduced as the basis weight was
increased.
Shearing (Mixing) Effect
Figures 6 and 7 show that the PAM-based white water was
very sensitive to shearing (mixing) effect. All the slurries used
in the two figures had exactly the same composition: 165 ppm
of PAM, ~2 ppm dispersant, ~1 ppm defoamer and a fiberglass
consistency of 0.012%. The variations in drainage rate were
caused solely by different shearing (mixing) history. In Figure
6, all the slurries were prepared with a fixed mixing time of 5
minutes, but, mixing pressure on the air motor was varied
from 14 to 60 psig. In Figure 7, all the slurries were prepared
with a fixed mixing pressure of 40 psig, but mixing time was
varied from 5 to 200 minutes.
Figure 6 indicates that, as mixing pressure was increased
from 14 to 60 psig, the viscosity of white water was reduced
slightly (from 2.5 to 2.24 cps, ~10% reduction), however, the
rate of drainage was increased by ~70%. Both wires A and B
responded to the shearing effect similarly.
At a fixed mixing pressure of 40 psig, as illustrated in
Figure 7, the prolonged mixing dramatically increased the rate
of drainage. As the mixing time was extended from 5 to 30,
67, and 200 minutes, the rate of drainage was increased by
~90%, 130% and 220%, respectively. In the meantime, the
white water viscosity was reduced from 2.29 to 2.20, 2.05 and
1.78 cps, respectively.
In Figure 8, all the data points in Figures 6 and 7 were combined
and replotted against the viscosity of white water. It
clearly indicates that the two sets of data (from Figures 6 and
7) followed a similar trend with respect to the white water vis-
INJ Summer 2001 17

Figure 6
EFFECT OF MIXING PRESSURE ON DRAINAGE.
(CONSISTENCY 0.012%, PAM 165 PPM,
DISPERSANT 2 PPM, DEFOAMER 1 PPM,
MIXING TIME 5 MIN.)
Figure 8
DRAINAGE RATE VERSUS
WHITE WATER VISCOSITY
(CONSISTENCY 0.012%, PAM 165 PPM,
DISPERSANT 2 PPM, DEFOAMER 1 PPM)
Drainage index, as defined in Eqn. 1, is a calculated value [16,
17] that takes into account for both the structural parameters
and air permeability of a forming fabric.
Where, AP is the air permeability in cubic feet per
minute (CFM) per square foot, Nc is the CD (cross or transverse
direction) mesh count, and b, as defined in Eqn. 2, is the
CD support factor on the sheet side.
Although drainage index is usually believed to be a more
(1)
(2)
Figure 7
EFFECT OF MIXING TIME ON DRAINAGE.
(CONSISTENCY 0.012%, PAM 165 PPM,
DISPERSANT 2PPM, DEFOAMER 1 PPM,
MIXING PRESSURE 40PSI)
cosity. The two wires A and B, again, responded similarly to
the mixing effect. The results in Figure 8 indicated that the
strong mixing (shearing) effect has broken the PAM molecular
structures, resulting in a reduction in flow resistance.
Forming Wire and Drainage
As mentioned earlier, wet process drainage is a filtration
process and depends on both the characteristics of white water
chemistry and the structures of a forming fabric. In the paper
industry, air permeability (AP) and drainage index (DI) are the
two parameters that are believed closely related to the
drainage performance of a forming fabric. Air permeability is
an experimentally determined value that measures the air flow
rate in cubic feet per minute (CFM) per square foot of fabric.
accurate prediction for the drainage capability of a forming
fabric on a paper mill, there have been only a few reports [16,
17] that correlated the rate of drainage to drainage index. On
the other hand, there have been no known reports that
addressed how drainage index and air permeability of a forming
fabric affect the rate of drainage in a WFGM process. The
following discussion would provide some interesting results.
Air Permeability
Figure 9 is a plot of drainage rate versus the wire air permeability
under various experimental conditions. The results
shown in Figure 9 included pure water, white waters with different
PAM concentrations, and fiberglass slurries at various
consistencies. The legend “water” stands for pure water; the
“WW” for white water with the last three digits representing
the PAM concentration in parts per million; and the “X-Y” for
a fiberglass slurry in white water, in which the first number, X,
represents the mat basis weight and the second number, Y, the
PAM concentration in parts per million. For instance, the legend
“WW033” represents a white water with a PAM concentration
of 33 ppm, and the legend “1.60-165” stands for a
18 INJ Summer 2001

drained faster than pure water, and a white water of 33 ppm
PAM drained faster than pure water with a coarse wire of air
permeability above 600 CFM. This was due to the streamingline-forming
characteristics of the polymer at very low concentrations
[15,18], which facilitated the drainage process.
Drainage Index
Figure 10 shows the dependence of drainage rate on
drainage index under various experimental conditions, and the
legends used in the figure are exactly the same as those in
Figure 9.
Drainage index is usually believed to be a more accurate
prediction for drainage in the paper industry, because it characterizes
both the sheet support (the b and Nc) and the initial
flow resistance (the AP) of a forming fabric. However, Figure
10 indicates that drainage index failed to predict the rate of
drainage in the WFGM process. It was expected that for the
three fabrics used in this investigation, the drainage rate would
monotonically increase with the increase in drainage index. As
shown in Figure 10, however, none of the drainage lines
showed monotonic increase with drainage index. Some of the
drainage lines decreased monotonically and the others
increased first, but then decreased as the drainage index was
increased.
There are no known answers at this time why the drainage
Figure 9
EFFECT OF WIRE AIR PERMEABILITY
ON DRAINAGE
Figure 10
EFFECT OF WIRE DRAINAGE INDEX
ON DRAINAGE RATE
fiberglass slurry that has a PAM concentration of 165 ppm and
would form a mat of 1.60 pounds/CSF after being dewatered.
Figure 9 indicates that for pure water and the white waters
at various PAM concentrations, air permeability was a good
prediction for the rate of drainage. The drainage line for pure
water and the four lines for white waters (WW010, WW033,
WW066, and WW165) all increased monotonically as air permeability
was increased from 465 to 715 CFM, and drainage
rate closely followed the air permeability of the forming fabrics.
For fiberglass slurries, however, the drainage responses
were more complex, and air permeability seemed unable to
predict the drainage rate of a forming wire. As shown in
Figure 9, the four drainage lines of 1.00-66, 1.60-66, 1.00-
165, and 1.60-165 increased monotonically with the increase
in air permeability. However. the other two lines of 2.30-66
and 2.30-165 first increased, but then decreased as the air permeability
was raised. Also, most drainage lines of the fiberglass
slurries tended to flatten out from AP 630 to 715 CFM,
though they increased sharply as the AP was increased from
465 to 630 CFM. It seems true that the higher the mat basis
weight and the higher the PAM concentration, the more likely
the air permeability would fail to predict the rate of drainage.
It is also worth noting that in Figure 9 the entire line of
WW010 and part of the line of WW033 are above the drainage
line of pure water, meaning that a white water of 10 ppm PAM
INJ Summer 2001 19

index failed to predict the rate of drainage of fiberglass slurries.
It is believed that the fundamental differences between
the WFGM and the papermaking processes are among the
probable causes, assuming that drainage index correlates well
in a papermaking process. A paper furnish typically uses short
cellulose fibers with high content particulate fillers at relatively
high consistencies, while a wet process slurry usually consists
of very long glass fibers with nearly zero percent particulate
substances at very low consistencies. A high concentration
of long molecular chain polyacrylamide in the white
water also makes the wet process different from the papermaking
processes. Johnson conducted [16] simulated experiments
with fiber lengths of 1 to 4 mm and reported that [17]
drainage was proportional to the fabric drainage index in a
papermaking process. In this study, the input materials were
~100% 1.25 inch (~32 mm) glass fibers with no particulate
additives at all. The PAM concentration was also higher than
in a papermaking process.
Conclusion
Wet process drainage is a complex filtration process
depending on both the characteristics of a fiberglass slurry and
the structures of a forming fabric. By employing a recently
developed wet process mimic device, a lab tester, the present
investigation has successfully conducted drainage experiments
of fiberglass slurries under simulated dynamic conditions
with a real (commercial) forming fabric in position. The
effects of wire parameters and white water characteristics
were examined.
The drainage experiments have shown that in a typical polyacrylamide
(PAM) white water, a higher PAM concentration
significantly reduced the rate of drainage, presumably due to
a higher viscosity. The PAM-based white water was also very
sensitive to shearing (mixing) effect. So, an increase in input
mixing energy, either by a higher mixing speed (RPM) or by
a prolonged mixing time, has reduced the white water viscosity,
and resulted in a substantial increase in wet process
drainage.
Mat basis weight also had a strong impact on wet process
drainage. Although an increase in mat basis weight has always
reduced the rate of drainage, its influence was stronger on the
wires with a higher air permeability and a lower drainage
index than on the wires with a lower air permeability and a
higher drainage index.
Another important conclusion of the study was that
drainage index did not predict wet process drainage, and the
main causes are believed to lie in the fundamental differences
between the WFGM and papermaking processes.
This investigation has also showed that the correlation
between air permeability and wet process drainage was complex.
While the drainage rate of pure water and of the wet
process white water (without fibers) correlated well to the initial
flow resistance (the air permeability) of a forming fabric,
for fiberglass slurries, however, the correlation failed under
some circumstances. It is generally true that while air permeability
may be used as an empirical parameter for light weight
mats at lower PAM concentrations, the higher the web basis
20 INJ Summer 2001
weight and the higher the PAM concentration, the more likely
it would fail to predict wet process drainage
Acknowledgements
The author would like to acknowledge Howard Ruble for
his assistance on the drainage experiments. He also wishes to
thank David Mirth, Thomas Miller, Robert Houston, David
Gaul and Warren Wolf for their support to publish this work.
References
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6. Unbehend, J.E., 1990 Papermakers Conference Proc.,
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7. Estridge, R., Tappi J.: 45(4), 285 (1962).
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15. Dong, D, “Development of Wet Process Mimic Device,”
Tappi Proc. 1999 Nonwovens Conference, Orlando, Florida,
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16. Johnson, D.B., Pulp Paper Canada, 85(6), T167 (1984).
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18. Bird, R.B., R.C. Armstrong and O. Hassager,
“Dynamics of Polymeric Liquids,” 2nd Ed., Wiley-
Interscience, New York, 1987.
— INJ

ORIGINAL PAPER/PEER-REVIEWED
Effects of Water On Processing
and Properties of Thermally
Bonded Cotton/Cellulose
Acetate Nonwovens
By Xiao Gao, K.E. Duckett, G. Bhat, Haoming Rong, University of Tenessee, Knoxville, TN
Abstract
Environmentally friendly nonwoven fabrics can be formed
through thermal bonding of cotton and cellulose acetate fiber
blends at reduced bonding temperature with the aid of a plasticizer.
Water has been introduced as an external plasticizer to
lower the softening temperature of cellulose acetate fibers and
to enhance the tensile strength of cotton/cellulose acetate web.
It has been found that water can significantly increase the tensile
strength of cotton/cellulose acetate thermally-bonded webs
at reasonable bonding temperatures. In addition, water can
enhance web bonding to essentially the same degree as an acetone
treatment does. The mechanisms of water effect are considered
and optimal processing conditions are proposed.
Introduction
More and more nonwovens are used in everyday life, but the
environmental impact of disposable products remains a major
concern [1, 2]. Manufacturers are seeking ways to produce
biodegradable textile products by using biodegradable fiber and
cotton becomes an obvious choice for the nonwoven industry
because of its biodegradability, softness, absorbency and vapor
transport properties [13]. However, cotton is a non-thermoplastic
fiber and requires the addition of a thermoplastic binder fiber
for the fusion of the fibers at relatively low temperature. Most
cotton-based nonwovens products are processed with binder
fibers using thermal calendering, which is a clean and an economical
process. Synthetic fibers such as low melting polyester,
polyester copolymer, polypropylene and polyethylene can be
used as binder fibers [3-7]. Cellulose acetate fiber also has been
used as the biodegradable binder fiber, since it is a thermoplastic,
hydrophilic and a biodegradable fiber. A solvent treatment
has been introduced in order to modify the softening temperature
of cellulose acetate fiber and to lower the calendering temperature,
while maintaining enhanced tensile properties.
Duckett, Bhat and colleagues [8, 9] have examined the effect of
acetone vapor pre-treatment and of 20% acetone solution pretreatment
on cotton/cellulose acetate thermally bonded webs.
The results showed that these solvent treatments could decrease
the softening temperature of cellulose acetate fiber and produce
comparatively stronger webs. However, from a practical standpoint,
manufacturers do not like a process involving the use of
acetone because acetone evaporates easily, and is flammable
and toxic. These detrimental factors create major problems in
manufacturing and pollute the working environment. Also, consumers
may prefer not to buy acetone-treated products, which
they think may contain toxic substances. In our research, the
desire was to decrease the softening temperature of cellulose
acetate without the aid of acetone treatment by applying water
treatment – a treatment noted previously at Celanaese Acetate
[10] – prior to thermal bonding. Additionally, an industrially
modified (plasticized) cellulose acetate fiber was studied as an
alternative choice as binder fiber.
Experimental Procedures
The cotton fiber used in this research is a scoured and
bleached cotton fiber provided by Cotton Incorporated.
Properties include a 5.2% moisture regain value, 5.4 micronaire
value and an upper-half-mean fiber length at 2.44 cm.
Celanese Corporation provided both ordinary cellulose acetate
(OCA) and plasticized cellulose acetate (PCA). An ultra-light
fabric with basis weight around 35 g/m 2 (1 oz/yd 2 ) was chosen
for this research.
The experiment was a four-factor design with two replications.
The factors included were:
CA type: Ordinary CA (OCA) and Plasticized CA (PCA)
Temperature: 150 0 C, 170 0 C, 190 0 C
Blend Ratio: 75/25 and 50/50 (by weight) Cotton/Cellulose
Acetate
INJ Summer 2001 21

Pre-treatment: Without Water Treatment (nw)
Water Dip-Nip Treatment (dn)
20% Aqueous-Acetone Dip-Nip Treatment
A Saco-Lowell carding machine, with a collector drum circumference
of 142.2 cm (56 in.) and a drum width of 22.2 cm
(8.75 in.) was used to form the webs. The carded webs were cut
away from the drum and placed between two sheets of paper to
await pretreatment and thermal calendering. An H.W.
Butterworth & Sons padding machine was used for the dip-nip
pretreatment. The carded webs were placed between two fine
mesh screens and passed through a tray containing water or
acetone solution prior to going through padding rolls to
squeeze out excess liquid. Following this procedure, the webs
were ready to be thermally calendered using a Ramisch
Kleinewefers 60 cm (23.6 in.) wide five-roll calender. Only the
upper two rolls were used. The top calender roll had an
engraved diamond pattern resulting in 16.6 % bonding area and
the bottom roll was smooth. Both were made of stainless steel.
The rolls were heated by circulating oil and the nip roll pressure
was set at 25 KN. Roll feed speed was fixed at 10 m/min.
All pretreated webs were placed in a standard atmosphere for
24 hours before testing. Five 1 X 10 inch test specimens were
cut from the web along the machine direction and the tensile
properties were obtained using ASTM D 1117– 80 Standard
Test Method for Tensile Testing of Nonwoven Materials. A
Hitachi S-800 SEM provided information on bond structure
and fiber morphology. The SEM was set at 1 Kev, 7 mm working
distance, and magnification of 80X and 250X, respectively.
Results and Discussion
In previous studies [11-13], a water spray treatment had been
used and there resulted a gradual increase in the peak strength
with each increasing bonding temperature compared with those
having no water spray treatment. This suggested the possibility
that water will act as a plasticizer to enhance fabric tensile
properties at reduced bonding temperature.
Figure 1
TREATMENT EFFECT ON THE
PEAK STRENGTH OF C/OCA WEBS
Treatment Effect
The effect of three different treatments on the tensile strength
of cotton/ordinary cellulose acetate (C/OCA) is shown in
Figure 1 for a 50/50 blend ratio.
From statistical analyses and visual observation, it is clear
that a water dip-nip treatment can significantly increase the
bonding strength of cotton/cellulose acetate thermally bonded
webs. Possible mechanisms that are responsible for this
strength enhancement are:
1. Water molecules penetrate the whole web with the assistance
of the padding machine and are attracted to the cellulose
acetate molecules by hydrogen bonding. Thus, the intermolecular
forces of cellulose acetate are reduced, and the mobility of
the polymer chains is improved. The polymer becomes elastic
and more flexible, with the result of a lowered softening temperature.
Hence, the softening temperature can be lowered by
the external plasticizer-water dip-nip treatment, providing
increased cellulose acetate molecular mobility and reducing the
necessary thermal energy required to bond the fibers at fiber
contact points. This makes it possible to bond at a lower temperature,
with the aid of a water dip-nip pre-treatment.
2. Due to the hydrophilic nature of the partially crystalline
structure of cellulose acetate, it can take up substantial water.
Above the softening temperature, the fiber swells as a result of
molecular chain relaxation and becomes sufficiently tacky to
provide some bonding with other binder fibers and with the
base fiber. The swelling, which provides greater free volume
for the polymer, will increase the surface area and enhance contact
with the other fibers. This might be expected to increase
bonding strength by providing more bonding area at the bonding
point.
3. When the web is passed through the nip of the pattern and
smooth rolls of the thermal calender, heat and pressure are
applied to the web. The web at that time is composed of cotton
fiber, cellulose acetate fiber and water. Water has very good
thermal conductivity – about 10 times that of either cotton or
cellullose acetate – and this enables additional heat transfer in
the short interval of time when web and rolls are in contact.
Thus, enhanced heating produces more polymer flow and better
bonding.
The external plasticizer-water bonds physically to the polymer
rather than chemically (covalently), which lowers the softening
temperature of cellulose acetate. In combination, this
enables more heat and polymer flow at the cross-over points of
fibers in the bonding region, providing enhanced tensile properties
to the web under lower bonding temperature.
From the graph, it can be clearly seen that there is no significant
difference between the two different kinds of external plasticizer
– water or 20% aqueous solution of acetone when applied
to the web by dip-nip pretreatment. Both plasticizations, however,
do increase the bonding strength of cotton/cellulose acetate
thermally bonded webs. These results suggest that water can
replace a 20% acetone concentration and can be used as the
external plasticizer in the pre-treatment of cotton/cellulose
acetate web, without a reduction in web strength.
Cellulose Acetate Type Effect
The effect of an internal plasticizer on the peak strength of
22 INJ Summer 2001

Cotton/PCA blend was examined, also. The results are shown
in Figure 2, separately by blend ratio and without any external
treatment.
It is clearly observed that the web containing plasticized cellulose
acetate (PCA) binder fibers has a significantly higher
peak strength than those comprising ordinary cellulose acetate
(OCA) binder fibers. The tensile strength rises uniformly to
9.00mN/tex for C/PCA-50/50 webs. This is to be compared to
0.85mN/tex for C/OCA-50/50 webs at the upper temperature of
190 0 C. This clearly demonstrates that the internal plasticizer
enhances the bonding and strength of a thermally bonded cotton/cellulose
acetate web.
All webs using PCA as binder fiber have significantly higher
peak strengths than those using OCA as binder fiber, except
for the 75/25 C/CA web bonded at 150 0 C. That may be due to
the low number of binder fibers (inhomogeneous fiber distribution)
and the lower bonding temperature, whereby the web
could not get sufficient heat flow and polymer flow to cause
suitable bonding. The effect may also be a statistical or processing
fluctuation, since the differences are so small.
Combination of PCA and Water Treatment Effect
When the water treatment is applied to Cotton/Plasticized
Cellulose Acetate (PCA) webs, the results are as shown in
Figure 3.
It is seen from the two figures that the cotton/plasticized cellulose
acetate webs have higher peak strength when treated
with an external plasticizer-water than those cotton/plasticized
cellulose acetate webs without water dip-nip treatment. The
possible exception may be for C/PCA-50/50-190ºC webs,
where there is little difference between the two treatments at the
highest bonding temperature.
The combination of internal and external plasticizer has a
significant effect in lowering the bonding temperature for
improved peak strength of cotton/cellulose acetate webs compared
to cotton/plasticized cellulose acetate webs, alone.
However, when the bonding temperature reaches 190 0 C, the
external plasticizer offers no significant benefit to the web
strength compared to the internal plasticizer effect alone. The
reasoning is that, at lower temperature, the internal plasticizer
helps decrease the softening temperature of cellulose acetate by
increasing the polymer chain mobility. The interaction between
neighboring polymer chains is still very high at low temperature
and more polymer chain flexibility and polymer flow are
required for effective bonding. When the external plasticizer –
water – is introduced into the web, it can decrease the interaction
between polymer chains, giving more mobility of the polymer
chain, thereby increasing the bonding surface area and
conducting more heat to induce the polymer flow to achieve
better bond strength.
When the bonding temperature reaches 190 0 C, the heat transfer
from the calender roll is sufficient for the polymer flow
around the other binder fiber or cotton fiber. If water is applied
at this time, the thermal dynamics of water may change considerably.
More heat may be taken away by evaporation than
the heat being conducted by water through the web. In this situation,
the water may not be as helpful to web bonding as at
Figure 2
CELLULOSE ACETATE FIBER EFFECT ON THE
PEAK STRENGTH OF C/CA WEBS
Figure 3
THE EFFECT OF COMBINATION OF PCA WITH
WATER ON THE PEAK STRENGTH OF WEBS
INJ Summer 2001 23

lower temperature. The web peak strength may decrease as a
result.
Temperature Effect
The bonding temperature is one of the most important factors
that directly affect bonding behavior. For C/OCA webs
without an external plasticizing treatment, the temperature has
no significant effect on web peak strength. Because the temperature
in the experimental range has not reached the softening
temperature (around 200 0 C) of ordinary cellulose acetate,
there is limited motion among segments in the polymer chain.
The mobility of polymer chains is simply not enough to move
out of the intermolecularly constrained structure to bond with
surrounding fibers.
When the water dip-nip treatment is applied to the C/OCA
web, there is no significant difference in the tensile strength in
the range of 150 0 C and 170 0 C. The peak strength increases substantially
only after the bonding temperature approaches
190 0 C. Water brings down the softening temperature of the cellulose
acetate. But at the higher temperature, the water increases
the heat flow into the bonding points and enhances bonding.
The same trend is observed when there is only an internal
plasticizer. The higher the bonding temperature, the stronger is
the web. When the C/PCA webs have been thermally bonded
with the aid of water pre-treatment, the softening temperature
of cellulose acetate can be further reduced by decreasing the
intermolecular forces in the polymer and increasing the mobility
of the polymer chain. Good bonding strength can be
achieved even at 170 0 C.
Blend Ratio Effect
The flow of heat into the fiber blend matrix is affected by
fiber distribution and blend ratio. However, based on statistical
analysis, there is no significant blend ratio effect on the C/OCA
web peak strength when other factors are kept the same.
For C/PCA webs bonded at 150 0 C and 170 0 C, there is a significant
blend ratio effect on the peak strength of the web that
is treated by the 20% aqueous solution of acetone. The reason
is apparently that the acetone treatment plays a much more
important role on increasing polymer chain mobility in cellulose
acetate at lower temperature, when compared to the temperature
effect. This goes along with the larger portion of
binder fibers that are available; thus, the polymer chain movement
and bonding effects are enhanced. At 190 0 C, significant
differences in peak strength are observed for different blend
ratios of C/PCA webs when there is no water treatment. The
bonding is enhanced as the binder fiber content is increased,
when the temperature is appropriate.
Bond Structure
Bonding points taken from C/PCA-50/50 webs were examined
and the effect of water treatment on bonding morphology
was characterized. From the SEM photos taken on C/PCA-
50/50 web bond areas (Figure 4), it is clearly seen that at the
same bonding temperature the integrity of bonding points was
enhanced with water dip-nip treatment. The edges of the bonding
points became much sharper and the fibers became much
flatter, thereby increasing the surface contact area and contributing
to better bonding. Solvent treatment improves the web
bonding structure at lower temperature, also.
In Figure 4, A3 and A4 show bonding points taken from
C/PCA-50/50 webs bonded at 190 0 C. These two bonding
points show less difference between treatment than those bonded
at 150 0 C. Both bonds are quite good and clearly visible. The
reason for the similarity is that the temperature is already high
enough for the CA fiber to stick to the surrounding fibers, irrespective
of treatment or no treatment.
The same conclusions can be drawn from examining the
fiber morphology inside the bonding areas at higher magnification
(Figure 5).
The fibers inside the bonding points without treatment look
rounder and less altered. However, the fibers inside the bonding
points, which have been water pretreated, look much flatter
and the edge of the fiber is not very clear. They have been
well integrated with surrounding fibers. The fibers became flatter
and softer with the water treatment. In the photo taken from
acetone treated bonding points, it is difficult to distinguish the
fiber inside the bonding point because the acetone treatment
has caused part of the cellulose acetate fiber to dissolve, thereby
preventing the fiber to retain its integrity. The fibers are well
bonded, but the previous comments help explain why acetone
treatment did not surpass water treatment as expected. That is,
some of the binder fibers were dissolved; therefore, the web
strength is decreased.
Figure 4
SEM PHOTOGRAPHS OF BOND POINTS
A1: 150 0 C-No Water A2: 150 0 C-Water DN A3: 190 0 C-No Water A4: 190 0 C-Water DN
24 INJ Summer 2001

No Water Water Dip-Nip 20% Acetone Solution
Figure 5
FIBER MORPHOLOGY OF C/PCA-50/50-150 0 C WEBS
BONDED UNDER DIFFERENT TREATMENTS
When SEM photos at different temperatures are compared
(Figure 4), it is observed that the bonding points become much
better defined with temperature increase, and the bonding
points look more uniform along the edge. It is easier to account
for the differences caused by the temperature, especially when
one compares the photos showing bonds at 150 0 C with those at
190 0 C.
Conclusions
1. Water as an external plasticizer, when applied to the web
by a dip-nip pretreatment, can significantly increase the tensile
strength of cotton/cellulose acetate thermally bonded webs at
reduced calender-roll temperatures.
2. Water can enhance the cotton/cellulose acetate web bonding
to essentially the same degree as an aqueous acetone treatment
and provide a good, safe and more economical choice for
industrial manufacturing of nonwovens.
3. The higher the calender roll temperature, the greater the
tensile strength of cotton/cellulose acetate thermally bonded
webs.
4. Plasticized cellulose acetate as binder fiber provides significantly
higher tensile strength to the cotton/cellulose acetate
thermally bonded webs than those incorporating ordinary cellulose
acetate as binder fiber.
5. The use of internal and/or external plasticizer can provide
choices of binder fiber and plasticizing treatment for better
bonding with acceptable physical properties. Two choices are:
• Cotton/Plasticized Cellulose Acetate-50/50-170 0 C – with
water treatment
• Cotton/Plasticized Cellulose Acetate-50/50-190 0 C – without
water treatment
References
1. John W. Bornhoeft, “The Development of Nonwoven
Fabrics and Products that are Friendly to the Environment,”
TAPPI Proceedings, 1990 Nonwovens Conference, p1
2. A. F. Turbak, “Nonwovens: Theory, Process, Performance,
and Testing,” TAPPI, Atlanta, GA, 1993
3. K.E. Duckett; Larry Wadsworth, “Tensile Properties of
Cotton/Polyester Staple Fiber
Nonwovens,” TAPPI Proceedings,
1987 Nonwoven Conference,
1987, p121-127
4. K.E. Duckett and L.C.
Wadworth, “Physical
Characterization of Thermally
P o i n t - B o n d e d
Cotton/Polyester Nonwovens,”
Proceedings of the 1988 TAPPI
Nonwovens Conference, 1988,
p99-107
5. Jerry P. Moreau, “Cotton
Fiber for Nonwovens,” June
1990 TAPPI Journal, 1990,
p179-184
6. K.E. Duckett and L.C.
Wadworth, and V. Sharma,
“Comparison of Layered and Homogeneously Blended Cotton
and Thermally Bonding Bicomponent Fiber Webs,” TAPPI
Journal, 1995, p169-174
7. Hsu-Yeh Huang and Xiao Gao, “Spunbond Technology,”
http://trcs.he.utk.edu/textile/nonwovens/spunbond.html, 1999
8. Greta Marie Heismeyer, “Biodegradable Staple Fiber
Nonwovens Calendered with the Assistance of An Aqueous
Solvent: Their Fabrication, Properties, and Structural
Characteristics,” Thesis, University of Tennessee, December,
1997
9. K.E. Duckett, G. Bhat, H. Suh, “Compostable Nonwovens
From Cotton/Cellulose Acetate Blends,” TAPPI Proceedings,
1995 Nonwovens Conference, p89-96
10. E. J. Powers, Celanese Acetate, private communication.
11. Gajannan Bhat, Kermit Duckett, and Xiao Gao,
“Processing and Properties of Cotton-Based Nonwovens,”
Proceedings of the Ninth Annual TANDEC Conference, Univ.
of Tenn.-Knoxville (Nov. 11, 1999)
12. K.E. Duckett, G.S. Bhat, X. Gao, H. Rong, and E.C.
McLean, “Characterization of Cotton/Cellulose Acetate
Nonwovens of Untreated and Aqueous Pretreated Webs Prior
to Thermal Bonding,” Proceeding of INDA/TAPPI, 2000
13. K.E. Duckett, G.S. Bhat, X. Gao, H. Rong, “Advances in
the Thermal Bonding of Cotton/Cellulose Acetate Nonwovens
of Untreated and Aqueous Pre-treated Webs,” Proceeding of
2nd International Conference on Metrology in Textile
Engineering, Lodz, Poland, Nov. 23-24, 2000
14. Glenn P. Morton, R.L. McGill, “Thermally Bondable
Polyester Fiber Effect of Calendering Temperature,” TAPPI
Proceedings, 1987 Nonwovens Conference, p129-135 — INJ
INJ Summer 2001 25

ORIGINAL PAPER/PEER-REVIEWED
Microstructural Analysis of Fiber
Segments In Nonwoven Fabrics
Using SEM and Image Processing
By E. Ghassemieh, H.K. Versteeg and M. Acar, Wolfson School of Mechanical and Manufacturing
Engineering, Loughborough University, Loughborough, UK
Abstract
In this paper image analyzing methods are established and
presented to study the microstructural changes of the nonwovens
made by hydroentanglement process. Fast Fourier transform
is used to obtain the orientation distribution of the
fibers. The distribution of the length of the straight segments
of the fibers is evaluated by application of Hough Transform.
The microstructural changes are correlated with the tested
mechanical properties of the nonwoven fabrics.
Keywords
Nonwoven, Fast Fourier Transform, Hough Transform,
Microstructure, Scanning Electron Microscope
Introduction
Hydroentanglement is a nonwoven fabric bonding technology.
It uses very fine high-velocity jets of water that drive the
fibers into the thickness of a web, resulting in reorientation
and entangling of the fibers. Hydraulic drag forces cause the
fibers to twist, bend and rotate around themselves and other
fibers to form a series of small, interlocking entanglement.
Thus, the structure is bonded by friction, resulting in a soft
yet relatively strong fabric. In this way through this energy
transfer process the microstructure of the fiber assembly
changes and its mechanical properties are improved consequently.
The measurable characteristics of fiber segments include
length, thickness, curl and orientation. The distribution of
structural characteristics such as orientation and curl of fiber
segments in a nonwoven is very important when determining
the mechanical properties of the fabric. The response of the
fabric to the load, its modulus and strength directly depend
first on the physical properties of the fiber, such as fiber modulus,
diameter, length and cross section shape and secondly
on the arrangement of the fibers in the fiber assembly such as
the orientation, the curl and the friction of the fibers at the
points of the contact.
The initial fabric extension is mainly due to the taking up
of curled or slacked segments. The stress-strain property of a
nonwoven fabric is dictated by the orientation distribution of
fiber segments and the degree of slackness in the fiber network
as well. Fiber orientation distribution can also be used
as a measure of the anisotropy of the fabric. The length of the
straight segment of fibers is related to the level of the entanglement.
As the entanglement proceeds more knots and curls
and shorter lengths of free segments of the fibers are expected.
The energy of the water jet required to restructure the initial
web depends on the microstructure of the initial web that
goes under the process.
Therefore, measuring the microstructural parameters of the
fiber assembly can be of advantage in two different aspects.
The structural parameters resulted from image analysis of the
web can be used to identify the amount of energy needed to
entangle the fibers. Image analysis of the fabric estimates the
microstructural variables that can be applied to predict its
mechanical properties.
In this study we have investigated the microstructural
changes and mechanical property improvements in the fiber
assembly created by hydroentanglement. SEM micrographs
and the two dimensional Fourier analysis of the image is used
to estimate the fiber orientation distribution. In order to find
the distribution of the length of the straight segment of the
26 INJ Summer 2001

fibers the Hough transform of the image is evaluated. The
mechanical properties of the fabric are measured as well. The
relation of these microstructural variables and the mechanical
properties are analyzed.
Method Description
Estimation Of Fiber Orientation Using Fast Fourier
Transform
A Fourier transform decomposes an image from its spatial
domain of intensities into frequency domain with appropriate
magnitude and phase values. A higher rate of change in gray
scale intensity will be reflected in higher amplitudes. The frequency
form of the image is also shown as an image where
the gray scale intensities represent the magnitude of the various
frequency components. [1] A sample of the image of the
nonwoven fabric structure made by scanning electron microscope
is shown in Figure 1a. The two-dimensional Fourier
transform of this image results in a spectrum of Figure 1b.
A number of Fourier transform techniques are routinely
used in the field of image analysis. The most common
method is discrete Fourier transform. The Fourier transform
is useful in determining the rate at which intensity transition
occurs in a given direction in the image. Thus, if the fibers
are predominantly oriented in a given direction in a nonwoven
fabric, the spatial frequencies in that direction will be
low and the spatial frequencies in the perpendicular direction
will be high. We use this property of the Fourier transform to
obtain information on fiber orientation distribution in a nonwoven
fabric.
The transform is implemented by processing all rows one at
a time followed by all columns one at a time. The result is a
two dimensional set of values each having a magnitude and a
phase. By shifting the Fourier transform results the zero frequency
component is shifted to the center of the spectrum.
The quadrants one and three are swapped with quadrant two
and four. The image of the magnitude spectrum is then symmetrical
about the center of the image, and the center represents
the zero frequency. The magnitude of each frequency is
indicated by the intensity of the pixel at that location. Brighter
areas show higher magnitudes. Since the center of the spectrum
contains mostly the noise in the image, the magnitude
values of this section are zeroed and eliminated from the consequent
calculations.
In order to find the fiber orientation distribution, we first
select an annulus of width W at a radius r from the center of
the image. The cut-off size (the size of the central part that is
eliminated) and the width of the annulus W affect the results
and should be optimized.
The annulus is discretised to slices of about 10 degree. In
each slice, the energy or power spectrum is integrated to find
the total energy of the spectrum resulted from the fibers with
the orientation 90 0 degree offset in the range of that 10 0 . Since
the fiber orientation is limited to a range of 0-180 0 , the calculations
are in this range.
In integration process both the original slice and its symmetric
part are taken into account.
Figure 1a
Figure 1b
A SAMPLE OF SEM IMAGE OF THE FABRIC
AND ITS FFT SPECTRUM
Estimation Of Distribution Of Straight Segment of Fibers
Using Hough Transform
Hough transform is one of the most effective methods that
can be used in object detection in an image. Because it requires
that the desired features be specified in some parametric form,
the classical Hough transform is most commonly used for the
detection of regular curves such as lines, circles, ellipses, etc.
Here we use the Hough transform in detecting the straight segments
of the fibers in the fabric. The transform projects each
straight line in the image to a single point and any part of the
straight line is projected to the same point. [1]
A brief description of the procedure of applying the method
to our fabrics is followed. First, the pixel lines of the fibers are
detected by edge detection and then all the pixels with edge
magnitude higher than some threshold are considered as fiber
pixels. A binarised image is made of the original image with
maximum gray scale at the related fiber pixels and minimum
gray scale of the background. A sample of binarised image of
the fabric structure image is shown in Figure 2a.
The Hough space is discretised in both directions.
Descritisation of the new space parameters, change the con-
INJ Summer 2001 27

thickness and number of the fibers.
The results of the test samples show that our FFT (Fast
Fourier Transform) and post-processing method is able to
identify the fiber orientation distribution. The Hough transform
results of the test samples prove the validity of the
method in estimation of the length of the lines.
Test Results & Discussion
Figure 2a
Figure 2b
A SAMPLE OF BINARISED IMAGE AND
ITS HOUGH TRANSFORM SPACE
tinuous Hough space to a rectangular structure of cells called
accumulator array. Lines of fibers detected in the image cause
a high value of the corresponding cell in the accumulator
array. The cell values depend on the number of pixels or the
length of the line of fiber that relates to that cell. Therefore,
the line of the image can be detected by finding the maxima
in the accumulator space. The values of the cells can be correlated
to the length of the fibers. The number of the fibers in
the same range of length is counted and a histogram of the
fiber length distribution is obtained. The resultant Hough
transform analysis is presented in Figure 2b.
The main advantage of the Hough transform is that it is tolerant
of gaps in feature boundary descriptions and is relatively
unaffected by image noise.
Validation of the Method
In order to validate the developed method of estimating
fiber orientation distribution using Fast Fourier Transforms,
we have made some test samples. The test samples are images
made from simple lines with one of the graphic packages. In
these tests we investigated the effect of the orientation, length,
Tests On Image Formation and Pre-processing
The scanning electron microscope is used to make images of
the microstructure of the fabrics. The advantage of using SEM
in making the images is that SEM has a high depth of field
even at higher magnification. In some cases the depth of field
of the SEM can be considerably higher than an optical microscope.
Therefore, applying SEM has the advantage of bringing
more fibers in the fabric in focus. This results in including
more fibers of the depth of the fabric in the primary image. [2]
Different processing stages were tested to prepare the
images obtained from SEM for the FFT and Hough transform
analysis.
Several parameters in making the images at the stage of
using electron microscope and afterwards affect the image
processing analysis. Magnification and brightness are the
most important factors that are decided at the stage of making
SEM images. The frame shape, dimension and the format of
the image are factors that should be carefully chosen before
the transfer of the image to the processing stage. Each of these
parameters is studied and optimized through several tests.
The main parameters are described briefly as follows:
• Magnification-Sampling
The magnification and area covered in an image is an
important factor that can affect the results. These parameters
should be optimized to get an image which is representative
of the whole fabric and at the same time is recognizable to the
image processing methods. In our research we have tried to
use comparatively high magnification and for each fabric
more sample images have to be made and processed. The final
orientation distribution for each fabric is evaluated by summing
and averaging all the samples. In this practice each sample
result needs to be evaluated. The samples significantly different
from the average should be discarded.
• Image brightness
Our tests show whenever the brightness of the image is not
uniform, there is considerable error in the outcome of the processing.
Uneven brightness of the original image made by
SEM can occur because of overcharging of some parts of the
samples by long exposure to electron impact or by nonuniform
coating of the samples. A nonuniform brightness of the
image results in unequal contribution of different part of the
image in the image processing outcome. Therefore it is essential
to make the SEM images with uniform brightness.
• The image dimension and frame
The dimension of the image sent to the image analysis pro-
28 INJ Summer 2001

cessing has been modified to get the same width and height.
In this way fibers of all sizes and directions will have an equal
chance to be processed.
• Image Format
Another important factor in image analysis is the processing
of the initial image to be able to extract the necessary
information by various methods. Different processing methods,
such as threshholding and binarising images or skeletonizing,
have been tried. If the original image coming out of
SEM is of uniform brightness, the results of using the image
in its original state are very close to te binarised image. Since
both methods rely on the gray level differences and the
objects under investigation are the fibers, using binary images
that define the whole fibers as one level and the background
as the second level is reasonable.
Figure 3a
Fabric Test Results
Orientation Distribution
The fiber orientation distribution is evaluated using the
FFT method. Bonding of the fibers is provided through the
process of impacting the web with high-pressure water jets.
Each side of the fabric is processed through several passes.
The water jet reorients the fibers and migrates them from one
layer to the other layers. Through this process the number of
contact points on each fiber and in the whole fabric increases.
Consequently, a stronger fabric is made.
In this study two different fabrics are tested to see the effect
of the hydroentanglement process on the fiber orientation distribution.
(a) Viscose-Polyester fiber (70%-30%) with the 120 GSM
crosslaid web used as the supply for the first set of experiment.
The machine speed is 10 m/min. The pressure profiles
in different consecutive passes are shown in Table 1.
The first side of the fabric is processed through four different
passes and the second side is impacted by water jet in
three passes.
The results of the Fourier transform and fiber orientation
distribution estimated for the fabrics No. 1 and No. 3 are
compared in Figure 3a. The same comparison is made for
fabrics No. 5 and No. 7 in Figure 3b. As the starting web is
cross laid the main direction of the fibers is in the cross direction
which is 90 0 .
The results for fabrics No. 3 and No. 7 show a larger percentage
of fibers in the machine direction compared to No. 1
Table 1
VISCOSE–POLYESTER
(120 GSM)–CROSS LAID
Pressure(Bar)
First side pass No. Second side pass No.
1 2 3 4 5 6 7
60 100 130 130 110 130 130
Figure 3b
FIBER ORIENTATION DISTRIBUTION
VISCOSE-PET, 120 GSM, CROSSLAID
and No. 5, respectively. A more uniform fiber distribution is
achieved through the entanglement process. The changes of
the orientation distribution are more significant for the fabric
No. 3 compared to No. 1 than fabric No. 7 in comparison with
No 5. Since during the first side processing the fibers are
more easily reoriented because there is less bonding between
them. When the second side is impacted there are already
more entanglement points present between the fibers. This
makes the movement of the fibers more difficult. The relative
number of fibers in any direction correlates with the strength
and modulus of the fibers in that direction. The results of the
mechanical testing of these fabrics are shown in Table 2,
where CD is for cross direction, MD is for machine direction
and DD is about 45 0 which is about diagonal direction.
Table 2
VISCOSE–POLYESTER
(120 GSM)–CROSS LAID
Strength (MPa)
Modulus (Mpa)
CD MD DD CD MD DD
No. 1 1.31 0.33 0.42 1.08 0.13 0.28
No. 3 4.18 1.48 1.94 5.82 1.17 2.17
No. 5 6.41 2.49 3.35 9.76 2.18 4.76
N0. 7 6.49 2.96 3.73 12.23 2.99 5.22
INJ Summer 2001 29

Table 3
VISCOSE –POLYESTER (110GSM)–PARALLEL
Pressure(Bar)
First side pass No.
Second side pass No.
1 2 3 4 5 6 7
50 100 120 120 100 120 120
(b) Viscose-Polyester fiber (70%-30%) with the 110 GSM
Parallel web used as the supply for the second set of experiment.
The machine speed is 10 m/min. The pressure values in
different consecutive passes are shown in Table 3:
The first side of the fabric is processed through four different
passes and the second side is impacted by water jet in
three passes.
The fiber orientation distribution estimated for the fabrics
after the first and third pass No. 1 and No. 3 are compared in
Figure 4a. Fabrics No. 5 and No. 7 are tested to see the effect
of the water jet impact on the second side of the fabric. The
results of these tests are shown in Figure 4b. In this case for
a parallel web the main direction of the fibers is in the
machine direction. The maxima of all the bar charts occur at
0 0 and 180 0 degrees. As the results show, for both sides more
fibers migrate from the machine direction to the cross direction
as the entanglement process progresses. Although still
for each fabric there are more fibers aligned in the machine
direction compared to cross direction. For this fabric as well,
the results indicate that more reorientation of the fibers occurs
in the first side processing compared to the second side processing.
The results of the mechanical testing of these fabrics are
shown in Table 4.
The modulus results confirm the outcomes of the comparison
of the orientation distribution. The modulus in machine
direction is higher for all the cases. The modulus of cross
direction increases from fabric No. 1 to No. 3 and from No. 5
to No. 7. The rate of increase for the former is higher than the
latter.
Distribution Of The Length of Straight Segment of
the Fibers
The distribution of the length of the straight segment of
fibers for Viscose-PET 70/30 120 GSM made from cross laid
web is evaluated by applying Hough transform analysis.
Images of the fabrics after different passes are provided and
tested. The results of the Hough transform and post-processing
described earlier are shown in Figures 5a and 5b. The
pressure values at different passes are as mentioned in Table
1. Figure 5a shows the fiber length distribution for the fabric
No. 1, No. 2 and No. 3, which are the fabrics processed on the
first side. As the length distribution for these fibers verifies,
the length of the straight segment of the fibers in fabrics No.
2 and No. 3 is less than that of No. 1. The results of the second
side for the fabrics No. 5 and No. 7 are presented in
Figure 5b. The same trend of change is observed as the length
of the straight segment of the fiber decreases in fabric No. 7
Figure 4a
Figure 4b
FIBER ORIENTATION DISTRIBUTION,
VISCOSE-PET, 110 GSM, PARALLEL
compared to the No. 5.
It should be mentioned that the actual length of the fibers
does not change through the process and the web is made of
fibers of more or less equal length. However as the entanglement
process proceeds more fibers are moved from one plane
to other ones and at the same time they bend and curl. This
results in reduction of the length of the straight segment of
fiber that is detected by the Hough transform analysis.
Therefore the most frequent fiber length in each distribution
curve correlates with the degree of bonding achieved through
entanglement. The lower the most frequent fiber length, the
more entanglement is obtained.
Conclusions
Image processing techniques are established and used to
study the microstructural changes in the nonwoven fabrics
developed by the hydroentanglement process. The techniques
Table 4
VISCOSE–POLYESTER (110 GSM)–PARALLEL
Strength (MPa) Modulus (MPa)
MD CD MD CD
No. 1 2.58 0.51 2.73 0.19
No. 3 6.39 2.16 5.70 1.08
No. 5 7.49 2.60 10.25 1.79
No. 7 8.74 2.03 16.05 1.91
30 INJ Summer 2001

Figure 5a
Figure 5b
DISTRIBUTION OF THE STRAIGHT LENGTH OF
FIBERS, VISCOSE-PET, 120 GSM, CROSSLAID
have been validated by applying the method to sample images
with known properties. The key parameters at the stage of
making SEM images and afterwards that affect the image
analysis results are discussed. The distributions of the orientation
and length of straight segments of fibers are estimated
for Viscose-PET fabrics. Both parallel and cross laid webs
are tested. The results are in good correlation with the
mechanical properties of these fabrics.
Since the scanning electron microscope with a high depth
of field is used to make the images of the microstructure, the
methods can be applied to the heavy fiber assemblies of high
thickness. However, the image analysis methods established
can also be applied to the images of fibers obtained by other
microscopic techniques.
Acknowlegdements
The authors would like to acknowledge the financial support
that they received from EPSRC for this research.
References:
1. Image Processing, Analysis, and Machine Vision, M.
Sonka, V. Hlavac, R. Boyle, 1999, Brooks/Cole Publishing
Co.
2. Introduction to Electron Microscopy, C.E. Hall, 1966,
Mc-Graw Hill
— INJ
INJ Summer 2001 31

ORIGINAL PAPER/PEER-REVIEWED
The Role of Structure On
Mechanical Properties of
Nonwoven Fabrics
By H.S. Kim and B. Pourdeyhimi, Nonwovens Cooperative Research Center, College of Textiles,
North Carolina State University, Raleigh, NC
Abstract
The mechanical properties, namely, tensile modulus, maximum
stress in tension and elongation at maximum stress of
thermally point-bonded nonwoven fabrics with different
bonding temperature have been evaluated. Image acquisition
and analysis techniques have been used to quantify structural
parameters such as fiber orientation distribution function,
bond-region strain, and unit cell strain during controlleddeformation
experiments and to identify failure mechanisms.
We have shown that an in situ experimental visualization and
measurement of the structural changes occurring during controlled-deformation
experiments can help establish links
between mechanical properties and the structure properties of
nonwoven fabrics.
Introduction
The high rate of growth in nonwovens has led to a substantial
increase in research aimed at establishing links between
structure [1-2] and desired macroscopic properties of these
materials [3-6]. However, few attempts have been carried out
at the macro scale without a sufficient insight into the mechanisms
responsible for the deformation characteristics of
these fabrics [7].
We recently developed a new device for in situ monitoring
of the changes in the structure of a nonwoven fabric during its
deformation [8]. In this study, these structural and deformation
parameters such as fiber orientation distribution function,
bond-region strain, unit cell strain, etc., under tensile deformation
of the nonwoven fabric were explored to provide
directions for establishing appropriate constitutive relations
for mechanical behaviors as well as failure criteria. In this
summary paper, we outline the role of structure on the
mechanical properties of nonwovens.
bonding the fibers was varied from 140 0 C to 180 0 C in increments
of 10 0 C at a constant calendar roll pressure of 40 psi.
The nonwovens produced had a final weight of 24 g/m 2 .
Tensile Testing
Each nonwoven tensile-test sample measured 15 cm X 2.5
cm. The samples were tested on an Instron tensile testing
machine at an extension rate of 100%/min. The clamps used
were 5 cm wide and 2.54 cm high. The gage length used was
10 cm. Testing was carried out on samples cut at ten-degree
azimuthal intervals. The data represent the averages and the
standard deviations obtained from five measurements in each
case. The maximum stress, the elongation at maximum stress
and the secant modulus at 10% elongation were obtained
from the load-elongation data.
Image Acquisition During Tensile Testing
The components of the concurrent tensile testing and image
acquisition instrument are shown in Figure 1. The tensile unit
Figure 1
THE DEVICE FOR CHARACTERIZING
STRUCTURAL CHANGES IN NONWOVENS DUR-
ING LOAD-DEFORMATION EXPERIMENTS
Load
Cell
Material and Methods
The nonwoven fabric was made from staple, carded
polypropylene webs. The temperature of calendar rolls for
32 INJ Summer 2001

a = 0.50 mm
b = 1.01 mm
c = 2.26 mm
d = 1.51 mm
q = 34 0
58 spots/cm 2
Secant Modulus
(at 10% Elongation (N/mm)
Load Direction (Angle)
Figure 2
DETAILS OF UNIT CELL DESCRIPTIONS
Machine Direction
Figure 4
TENSILE SECANT MODULUS AS A FUNCTION
OF THE TEST STRIP DIRECTION
determined by using the Fourier method previously discussed
[5]. A typical ODF is presented in Figure 3.
Results and Discussion
% Frequency
Orientation Angle
Figure 3
TYPICAL FIBER ORIENTATION DISTRIBUTION
has been designed such that, for each strain increment, the jaws
move by an equal distance in opposite directions. This arrangement
is necessary to monitor the structural changes as a function
of deformation in the same test zone. The light source for
illuminating the structure employs a special directional transmitted
lighting similar to the one described previously [3]. For
a complete description of the instrument, refer to our earlier
paper [8]. The results reported here were obtained with images
that were digitized at 5% strain increments.
The properties of most nonwoven fabrics, especially those
produced from carded webs, are anisotropic, i.e., they vary
according to the direction in which the fabric is tested. In
order to establish the efficacy of the current instrument in this
regard, tensile testing was performed at 0 0 (machine direction),
±34 0 (bond pattern stagger angles), and 90 0 (cross direction)
for all nonwovens produced at bonding temperatures,
140, 150, 160, 170, and 180 0 C. In the point-bonded nonwoven
fabric of the present study, these directions allow easy identification
of the repeating unit of the bond pattern (see Figure
2). The fiber orientation distribution function (ODF) was
Tensile Properties
The tensile moduli obtained from these measurements are
summarized in Figure 4. It is clear that the properties change
significantly with the bonding roll temperature. As expected,
the azimuthal tensile properties exhibit a symmetry that is
consistent with the fiber orientation distribution (Figure 3),
regardless of the bonding temperature. Bonding temperature,
however, is expected to influence the mechanical properties of
the nonwoven. This is the expected consequence of the higher
degree of melting and fusing of filaments at the higher temperatures,
evident in the images displayed in Figure 5. These
180 o C 140 o C
Figure 5
CONFOCAL IMAGES OF BOND SITE
24um
40 um
INJ Summer 2001 33

Maximum Stress (N/mm)
Elongation at
Maximum Stress (mm)
Load Direction (Angle)
Load Direction (Angle)
Figure 6
MAXIMUM TENSILE STRESS, AS A FUNCTION
OF THE AZIMUTHAL TEST STRIP DIRECTION
images were obtained at different depths by using a laser confocal
microscope. The stiffness of the bonded domains, and
thus the fabric, would be expected to increase with bonding
temperature, primarily due to the reduced freedom of interfiber
motions.
Two aspects can contribute together to the embrittlement
that results from bonding at the higher temperatures, one that
corresponds to the aforementioned changes within the bond
regions and the other to the changes that occur at the periphery
of these regions, especially the significant flattening of the
interface. Figure 6 shows the maximum tensile stress
obtained from all the azimuthal tests. The tensile strength
increases to a maximum with partial melting and recrystallization,
and the consequent inter-fiber fusion, when bonding
is carried out in the lower temperature region of the melting
range of polypropylene. However, it decreases with the onset
of large-scale melting that would occur at the higher bonding
temperatures. It should be noted here that the mechanism of
failure also changes around the bonding temperature that
yields maximum strength. At temperatures below this transition,
failure is almost always caused by inter-fiber disintegration
within the bond region. At higher temperatures, failure
occurs primarily at the periphery of the bond spot where the
fibers break at the interfaces of the non-bonded and bonded
domains. At high bonding temperatures, a sharp morphological
gradient would be established at these interfaces, due the
rigid bond domains that result from almost complete fusion of
the filaments and the non-bonded regions that remain essentially
unchanged from their original structure. Such a steep
gradient has been observed by micro-Raman spectroscopic
measurement [9]. The consequently sharp gradient in properties
should lead to high stress concentrations and premature
failure at this interface.
As seen in Figure 7, the strain at maximum stress does not
mirror the results obtained for the previous graph. The lack of
a simply correlated behavior of the two arises from the fact
that, while the critical condition for failure is most likely to be
a stress-based criterion, the corresponding strain would be
Figure 7
ELONGATION AT MAXIMUM TENSILE STRESS,
AS A FUNCTION OF THE AZIMUTHAL TEST
STRIP DIRECTION
dictated by the combination of the stress and the compliance
of the material at this critical point.
Orientation Distribution Function (ODF)
From the images digitized during tensile testing at 0 0 , +34 0 ,
90 0 , and -34 0 directions, the fiber orientation distribution function
(ODF), bond spot strain and unit-cell strain in the
machine (length) and cross (width) directions, as well as
Poisson’s Ratio were measured. For a description of these
parameters, refer to Figure 2. The fiber orientation distributions
were obtained from the images by using the Fourier
Transform methods described by Pourdeyhimi et al. [5].
The ODF was measured from a series of such images captured
at regular intervals of deformation at each test direction.
The ODF results are summarized in Figure 8 for samples tested
in the machine and cross directions. The orientation angle
is with respect to the angle between sample axis and loading
direction. When the samples are tested in the cross direction
(90 0 ), the dominant orientation angle changes from its
Figure 8
ODF AS A FUNCTION OF THE FABRIC STRAIN
FOR SAMPLES TESTED AT 90 O
(CROSS DIRECTION) LEFT, AND 0 O
(MACHINE DIRECTION) RIGHT
34 INJ Summer 2001

Bond Width Strain %)
Bond Height Strain %)
Figure 9
SCHEMATIC DEMONSTRATING STRAINS DUE
TO BOND SITE STRAIN AND FIBER STRAIN
tions and fiber deformations would be different. The reorientation
appears to be dictated by the anisotropy of the structure
and the bond pattern and may be responsible for the different
compliance values observed as shown in Figure 4.
The reorientation due to the test deformations imposed at
34 0 and -34 0 also show similar changes in the dominant orientation
angle, but of a much smaller magnitude than that
obtained at 90 0 .
It may be noted that the reorientation is similar for the fabrics
produced at different bonding temperature except that the
failure points are different. A rigid bond will result in premature
failure partly because of the high stress concentration
and thermal damage of fibers at the bond fiber interface while
low bonding temperatures yield more flexible bonds. As
shown in Figure 9, in the case of a flexible bond site, the
strain Dl comes from the strain of bond site. However, in the
case of a rigid bond site, the strain Dl mainly comes from the
strain of fiber. This phenomenon will be significant with
respect to the mechanical properties of the material, but it
does not significantly contribute to the structure changes
because of relatively lower stain of bond site than fibers
themselves.
Changes at the Bond Site
In the fabrics used in the present study, the diamond bond
geometry and the bonding pattern are such that the long
dimension (width) of the bond is along the cross direction and
the short dimension (height) is along the machine direction,
the preferred direction in the fiber ODF. The strains in the
bond along various directions are shown in Figure 10 as a
function of the fabric strain for all samples.
It is evident that, when the sample is tested in the machine
direction (0 0 ), the bond shape (width) changes significantly.
This occurs because:
(1) The compression or tensile stiffness of bond site in the
machine direction where the fibers are mainly oriented is
much higher than that in the cross direction.
(2) In the case of samples tested in the cross direction (90 0 ),
many of the fibers in the bond site are under little or no load
in the machine direction because both repositioning of the
bond sites and reorientation of the fibers towards the load
direction (cross direction) occur with relative ease.
Unit Cell Width Strain %)
Figure 10
BOND WIDTH STRAIN AS FUNCTION OF
FABRIC STRAIN (LEFT) AND BOND HEIGHT
STRAIN AS A FUNCTION
OF FABRIC STRAIN (RIGHT).
Figure 11
UNIT WIDTH STRAIN AS FUNCTION OF FABRIC
STRAIN (LEFT) AND UNIT HEIGHT STRAIN AS
A FUNCTION OF FABRIC STRAIN (RIGHT)
Consequently, the bond site appears to be much more compliant
in the cross direction than along the machine direction
at all bonding temperatures.
Changes in the Unit Cell
The strains in the unit cell along the cross and machine
directions, which result from macroscopic tensile deformation,
are reported as a function of macroscopic fabric strain in
Figure 11. As noted earlier, the significant fiber reorientation
and a substantially higher degree of compliance of the bond
site in the cross direction result in higher strains in the unit
cell in the cross direction. Bonding temperature appeared to
have little or no effect on this behavior.
The propensity for shear deformation along the direction of
preferred fiber orientation is also manifested in these tests.
The unit-cell shear deformation results are shown in Figure
12. It is clear that application of a macroscopic tensile strain
produces a significant shear deformation along the initially
preferred direction in fiber ODF, except when the two directions
are either parallel or normal to each other for all nonwovens
produced at different bonding temperatures. The
samples subjected to tensile testing at 34 0 and -34 0 , exhibit
substantial shear deformation. An important consequence of
this effect is in the failure process, which shows a propensity
Unit Cell Height Strain %)
INJ Summer 2001 35

Shear Angle (Degree)
Poisson’s Ratio
1mm
Figure 12
SHEAR ANGLE AS FUNCTION
OF FABRIC STRAIN
42.5%
47.5%
52.5%
Fabric Strain %)
Figure 13
IMAGES CAPTURED DUR-
ING TENSILE TESTING IN
THE -34 O DIRECTION
SHOWING SHEAR FAILURE
for its propagation in
the shear mode along
the dominant fiber orientation
direction,
unless the macroscopic
tensile stress is applied
along, or close to, 0 0 or
90 0 (Figure 13). The
latter cases lead to failure
in the tensile mode.
Similar to other data
presented above, the
bonding temperature
has little or no effect on
the shear behavior.
Again, the effect of the
structure is dominant.
The Poisson’s Ratio
calculated from the unit
cell strains of all fabrics
produced at different
bonding temperature is
reported in Figure 14. It
may be noted that the
Poisson’s Ratio for the
samples tested in the
cross direction (90 0 )
appears to reach a maximum
followed by a
plateau while the
Poisson’s Ratio for the
samples tested in the
machine direction (0 0 )
goes through a maximum
followed by a
decrease. When the samples are tested in the machine direction,
the structure reorientation in the machine direction
(Fabric Strain %)
Figure 14
POISSON’S RATIO AS FUNCTION OF FABRIC
STRAIN AND LOADING DIRECTION
reaches a maximum rapidly and little or no change in the
transverse direction occurs thereafter. When the samples are
tested in the cross direction, however, the large deformation
occurring in the cross direction is accompanied by much
smaller strains in the transverse direction. The structure reorientation
as well as bond strain contributes to the total structure
deformation. Much of the transverse strain is related to
the compressible mobile structure of nonwovens with spatial
regions not occupied by fibers. In the case of samples tested
in the machine direction, the relatively high compression
forces and high stiffness in the cross direction result in structure
jamming at low levels of strain. This is demonstrated in
Figure 15.
Conclusion
The symmetry in the fiber ODF is, as expected, reflected in
the mechanical properties of nonwovens. However, the
dependence of these properties on the azimuthal angle may
not be a weighted function of the fiber ODF. It is important to
recognize that the ultimate properties of a nonwoven would
be dictated not only by the structural features and properties
of the pre-bonded fabric, but also by the conditions of the
bonding process.
The data suggest that failure of thermally bonded nonwoven
structures is likely to be governed by critical-stress based
criteria. They also point to a change in the failure mechanism,
from fiber/fiber interfacial failure within the bonds at lower
bonding temperatures to failure initiated at the bonded/nonbonded
interfaces at higher bonding temperatures. It has also
been revealed that, while failure can follow different modes,
it is likely to be dictated, under most conditions, by shear
along the preferred direction of fiber orientation.
A substantial deformation-induced reorientation occurs in
the fiber ODF, especially when deformation of the fabric is
carried out normal to the direction of preferred fiber orientation.
This reorientation-assisted deformation, requiring relatively
low forces, also results in a high overall strain-to-failure
even when failure occurs at a relatively low stress. To that
36 INJ Summer 2001

Figure 15
IMAGES CAPTURED AT 50% FABRIC TENSILE
STRAIN WITH A SAMPLE TESTED IN THE
CROSS DIRECTION (LEFT) AND
MACHINE DIRECTION (RIGHT)
5. Pourdeyhimi, B., R. Dent, and H. Davis, “Measuring
Fiber Orientation in Nonwovens, Part III: Fourier
Transform,” Textile Research Journal, 67, 143-151, (1997).
6. Pourdeyhimi, B., R. Dent, A. Jerbi, S. Tanaka and A.
Deshpande, “Measuring Fiber Orientation in Nonwovens,
Part V: Real Fabrics,” Textile Research Journal, 69, 185-92,
(1999).
7. Thorr, F., J.Y. Drean, and D. Adolphe, “Image Analysis
Tools to Study Nonwovens,” Textile Research Journal, 69,
162-168 (1999)
8. Kim, H.S., Deshpande, A., Pourdeyhimi, B., Abhiraman,
A.S. and Desai, P., “Characterization of Structural Changes in
Point-Bonded Nonwoven Fabrics During Load-Deformation
Experiments,” Textile Research Journal, In Press.
9. Michielsen, S., NCRC Semi-Annual Report, October
2000. — INJ
bonded interfaces at higher bonding temperatures. It has also
been revealed that, while failure can follow different modes,
it is likely to be dictated, under most conditions, by shear
along the preferred direction of fiber orientation.
A substantial deformation-induced reorientation occurs in
the fiber ODF, especially when deformation of the fabric is
carried out normal to the direction of preferred fiber orientation.
This reorientation-assisted deformation, requiring relatively
low forces, also results in a high overall strain-to-failure
even when failure occurs at a relatively low stress. To that
end, it has been shown that bonding temperature (a most
important processing parameter) has little or no effect on the
structure reorientation.
Acknowledgements
This work was supported by a grant from the Nonwovens
Cooperative Research Center (NCRC), North Carolina State
University. Their generous support of this project is gratefully
acknowledged.
References
1. Kim, H.S., Pourdeyhimi, B., Abhiraman, A.S. and Desai,
P., “Angular Mechanical Properties in Thermally Point-
Bonded Nonwovens, Part I: Experimental Observations,”
Textile Research Journal, In Press.
2. Lee, S.M. and A.S. Argon, “The Mechanics of the
Bending of Nonwoven Fabrics, Part I: Spunbonded Fabric
(Cerex),” Journal of the Textile Institute, No. 1, 1-11, (1983).
3. Pourdeyhimi, B. and B. Xu, “Characterizing Pore Size in
Nonwoven Fabrics: Shape Considerations,” International
Nonwovens Journal, 6, (1), 26-30, (1994).
4. Pourdeyhimi, B., R. Ramanathan and R. Dent,
“Measuring Fiber Orientation in Nonwovens, Part II: Direct
Tracking,” Textile Research Journal, 66, 747-753, (1996).
INJ Summer 2001 37

ORIGINAL PAPER/PEER-REVIEWED
Studies on the Process of
Ultrasonic Bonding of Nonwovens:
Part 1 — Theoretical Analysis
By Zhentao Mao 1 and Bhuvenesh C. Goswami 2 , School of Textiles, Fiber & Polymer Science
Clemson University, Clemson, South Carolina, USA
Abstract
A model has been developed to predict the bonding behavior
of nonwovens during the ultrasonic bonding process. The
model includes the following subprocesses: mechanics and
vibrations of the web and horn, viscoelastic behavior of webs
and heat generation, and heat transfer. Each subprocess was
modeled first and then combined together with the boundary
conditions to develop an overall process model. The compressional
behavior and thermal conductivity of webs will be
discussed and their appropriate equations have been chosen
for model. A Finite Element Method (FEM) was used to solve
the above coupled model. Subsequently, the heat generation
rate and the temperature change during the bonding process
were calculated.
Introduction
Ultrasonic bonding of nonwoven fabrics is accomplished
by applying high frequency vibrations to the webs to be welded
together. Thermal energy can be generated in a web that
can cause the web temperature to rise so high that it can be
sufficient to soften and weld the fibers at the bonding sites
and to cause molecular diffusions and entanglements; consequently,
the fibers fuse together and form bonds when they
cool down. The important components of a nonwoven ultrasonic
bonding machine are the power supply, converter,
booster, horn, pneumatic pressure system, anvil, and weld
and hold time controllers.
The generation of ultrasonic energy starts with the conversion
of simple 50 or 60 Hz electrical power to high-frequency
(usually 20 KHz) electrical energy. High-frequency electrical
energy is conducted to an electro-mechanical converter,
1. Current address: Broadband Communications Sector, Motorola
Inc., Duluth, GA 30096, USA
2. Address all correspondence
38 INJ Summer 2001
or a transducer, where high frequency electrical oscillations
are transformed into mechanical vibrations. The heart of the
converter is an electrostrictive element which expands and
contracts when subjected to an alternating voltage. These
mechanical vibrations are transferred to the web via a waveguide
assembly. The horn is pressed against the web by a
pneumatic pressure system so that vibrations are introduced
to the web under the action of forces. The direction of these
horn vibrations is perpendicular to the web. The anvils are
made to have various patterns to produce fabrics with different
bond designs. The weld time and hold time controllers are
adjusted for different types of fibers and webs. The frequency
most commonly used is 20,000 Hz for ultrasonic bonding
of nonwovens. A line diagram of the head of an ultrasonic
unit is shown in Figure 1.
There are only three ultrasonic process variables: amplitude,
pressure and time. These process variables are roughly established
by trial and error and then finally adjusted to meet the
needs of a specific application. In actual production these variables
are easily controlled. Amplitude is determined by the
selection of the booster and the horn design. Pressure is usually
generated by a pneumatic pressure system and can be easily
adjusted and regulated. Time is the function of the throughput
speed which determines the dwell time of the web (fibers)
under the ultrasonically vibrating horn. Other variables, for
example, are the weld area, fiber type and web unit area.
In ultrasonic bonding only energy and pressure are needed,
which are applied at the precise areas of the bond sites. Heat
energy is generated within the fibers which can minimize the
degradation of the material that may occur possibly due to
excessive heating. Since the ultrasonic process does not
depend on thermal conduction to get the thermal energy as in
the calender thermal bonding, the horn and anvil stay relatively
cool. It is much easier to maintain bonding energy
within the desired sites. There is little or no web damage out-

Figure 1
(A) WELDING SYSTEM; (B) A SERIES OF
VOIGT-KELVIN MODELS OF A WEB
side of the bond areas from hot areas such as in the calender
thermal bonding process. Moreover, ultrasonic bonding is
more efficient than the calender bonding. There is little heat
loss in the ultrasonic method. There is no pre-heating required
for ultrasonic bonding and the products can be made as soon
as the machine is turned on. But in the calender thermal bonding
the calender must be pre-heated to a certain high temperature,
which may take several hours before production begins.
After production ends it still takes several hours for the calender
to cool off.
Ultrasonic bonding is used to produce such products as
mattress pads and bedspreads. This bonding technique is efficient
in manufacturing these products because it eliminates
the costs associated with the needles and threads as in the
conventional sewing methods and it allows making different
patterns without lowering the productivity or quality.
Literature Review
Computer-based literature retrieval in the area of nonwovens
ultrasonic bonding revealed that there were no published
research papers that studied the fundamental mechanism of
ultrasonic bonding of nonwovens in details. Most of the published
work relates to empirical studies where the effects of
various process parameters on the physical and mechanical
properties of nonwovens have been described.
Flood [9, 10 and 11] published some general articles that
reviewed the patents, equipment and development of the
ultrasonic bonding machines for nonwovens. These papers
also discussed the benefits and applications of this particular
bonding technique. Rust [20] reported some experiments to
determine the effect of clearance of the concentrator (called
horn) and anvil, and concentrator load on selected nonwoven
fabric properties. But only a qualitative description of the
mechanism of the ultrasonic bonding was given. Floyd and
Ozsanlav [12] studied the ultrasonic bonding of various types
of fibers which for example included polypropylene and
nylon 6, 6. They found that an impressive feature of many
fabrics produced was their superior softness over comparable
products produced by calender bonding. They also found that
the high melting point fibers such as polyester and nylon 6, 6
were difficult to bond.
Due to the scarcity of available literature about the mechanism
of ultrasonic bonding of nonwovens, a search of the literature
about the mechanism of the ultrasonic bonding of
thermoplastics was made. There are a few research papers
published in open literature in this field. This is probably due
to the fact that the ultrasonic bonding method of thermoplastics
finds more extensive and important utilization in the plastic
industry rather than in the textile industry.
In one of the earlier investigations Matsyuk and
Bogdashevskii [16] carried out a study of lap joining of polymeric
materials with ultrasonic welding. A frequency of 20
kHz, amplitudes of 0.05 to 0.07 mm, and weld time ranging
from one to five seconds were used. The materials used in this
study were bulk polymethylmethacrylate (PMMA), plasticised
polyvinylchloride (PVC), polytetrafluoroethylene and
polyethylene. While studying the rate of temperature
increase, the researchers observed a change in the heating
rate, which correlated with the changes of the material from a
glass-like highly elastic state to a viscous state. Also, the
effect of the dimensions of the support holding the welded
parts was examined. It was observed that the pressure used to
press the parts together during welding has a considerable
effect on the strength of the weld. However, in almost all
cases the welded joints were found to be as strong as the original
material. Also, it was observed that the treatment of the
surface of thermally plasticised PVC with emery paper doubled
the shear strength of the welds.
Tolunay, Dawson and Wang [25] studied the ultrasonic
welding of polystyrene parts. They used dish-shaped polystyrene
specimens that were welded with ultrasonic vibrations
of 20 kHz frequency and 0.076 mm amplitude. Temperatures
at the weld interface and at two locations inside the energy
director were measured. Power input and horn displacement
was also measured during welding. Different welding forces
and times were used to simulate a wide range of welding conditions.
They found that increasing the static pressure resulted
in consumption of higher power levels, although bond
strength did not differ substantially. They also developed a
one-dimensional heat conduction model for an infinite slab,
and combined it with a viscoelastic heating model. The infinite
slab model overestimated the interface temperature and
underpredicted the bulk temperature (when compared to the
INJ Summer 2001 39

experimental measurements). Their paper also discussed
intermolecular diffusion. Based on the work of Wool and
O'Connor [30], Tolunay et al. [25] concluded that, even for
amorphous polystyrene, the interdiffusion time is one to two
orders of magnitude shorter than the weld time.
Land [15] used a high-speed camera to make the process
visible and gain some understanding of the melting and flow
of the material that occurred. They filmed the ultrasonic welding
of polycarbonate, glass reinforced polycarbonate (30% by
weight), ABS, nylon 6, glass-reinforced nylon 6 (30% by
weight), and polybutylene terephthalate. They noticed that the
welding process occurs in stages, rather than continuously, for
all of the materials examined. The gap between the parts alternately
decreases for a short time duration and then becomes
stationary. The number and durations of these gaps decrease
and stationary cycles vary for different materials.
Benatar and Gutoski [2] modeled the ultrasonic welding.
The model predicted that melting and flow occur in steps,
which was confirmed by experiments. Their paper also pointed
out that estimates of the healing time for semicrystalline
polymers are of the order of 10 -7 s, which are at least 6 orders
of magnitude less than the weld time for ultrasonic bonding.
This means that intermolecular diffusion presents no time
limitation to the welding process and it does not need to be
modeled. For all practical purposes, it can be assumed that
intermolecular diffusion occurs almost immediately after
melting and achieving the intimate contact at the interface.
They welded PEEK and graphite APC-2 composites and
observed excellent bond strength.
Chernyak et al. [6] modeled heat generation and temperature
change in a polyethylene rod during ultrasonic welding.
The assumption has been made that hysteresis losses are the
source of heat generation in the ultrasonic welding of plastics.
The temperature change obtained theoretically by solving the
problem of the heating of soft plastics on the basis of the
assumed mechanism of heat formation is in good agreement
with experimental results.
1. Web is assumed to be a viscoelastic material that can be
represented by a series of Voigt-Kelvin models as shown in
Figure 1.
2. Web properties such as the spring constant k and the
damping coefficient h are assumed to be constant independent
of temperature.
3. Rotary anvil is assumed to be rigid and experiences no
vibrations.
4. The effect of gravity on the web elements is negligible
when compared to the external forces exerted during vibration
by the horn.
The following symbols have been used:
F 0 the force applied to the web element 1 by the horn (N);
f mi the net force on the web element i (N);
f ki the spring force on the web element i (N);
f hi the damping force on the web element i (N);
v mi the speed of the web element i (m/s);
v ki the speed of the spring of the web element i (m/s);
v hi the speed of the dashpot of the web element i (m/s);
v p the anvil vertical speed at the web element n (m/s);
i 1, 2, ...., n, and n is the total number of the web elements.
The elemental equations can be derived from the Newton’s
Second Law. These elemental equations are combined to get
the state equations for the whole model. The state equations
are represented in Equations (1) through (9). There are totally
2*n equations with 2*n unknowns. The unknowns are F o ,
f k1 ,v m2 ,f k2 , ..., v mi ,f ki , ..., v mn , and f kn . These equations can
be solved by the Runge-Kutta method. From the vibration
theory vibrations are transient at first and then they will come
to steady states. We only need to calculate the results up to the
steady states and then the remaining vibrations are the same
as the calculated steady states.
One can get the following state equations:
(1)
Theoretical Model
A model of the mechanics and vibrations of the horn, the
web, and the rotary anvil is necessary for evaluating the vibrations
induced within the web. From the vibrations of the web,
it is possible to determine heat generation in the web. And,
from the heat generated, the temperature change during the
bonding process can be predicted. To form a good bond rapidly
it is necessary to concentrate the ultrasonic energy within
the web.
In order to clarify concepts of batts and webs in this paper,
batts mean the bulky material made by the Random Webber
as described later in Part 2 and they almost do not have any
strength. Webs mean the batts covered by spunbonded fabrics
on top and bottom surfaces. Webs here are referred to the
materials ready to be bonded. After bonding webs become
nonwoven fabrics.
In the development of a model for the vibration of the horn,
the web, and the rotary anvil, certain underlying assumptions
have to be made. These assumptions are:
40 INJ Summer 2001
So
(2)
(3)
(4)
(5)
(6)

(7) (13)
We need to know the initial conditions of the following
unknowns: f k1 ,v m2 ,f k2 ,…,v mi ,f ki , ...,v mn , and f kn . Though F o
is also an unknown we do not need to know its initial value.
This is easily seen from Equation (2). It does not involve the
derivative of F o and it can be simply calculated. From the theory
of vibrations, we know that the vibrations of the element
are transient at first and then they come to steady states.
In the calculations, the web is assumed to be moved forward
by the anvil step by step instead of continuously. So the
web is assumed to stay at a fixed position for a little while and
then jump forward to another fixed position and the jump distance
is just the assumed web moving step. The steady state
vibrations are the same regardless of the different practical
initial conditions for a given set of conditions such as the initial
force F o which is determined by the gauge setting and
pressure, the vibration amplitude and frequency of the horn.
We can use the following initial conditions.
Here the web is assumed to be divided into the same equivalent
elements with the same height. The total number of the
web elements is n. And h o is the hypothetical height of the
web and h is the distance between the horn and the anvil, i.e.,
the gauge. A is the area of the elements.
A viscoelastic material dissipates some energy through the
intermolecular frictional mechanism when it is subjected to a
sinusoidal strain. The storage modulus for a viscoelastic
material is the in-phase modulus and it is a measure of the
ability to store energy. The loss modulus is the out-of-phase
modulus and it is a measure of the energy dissipated. If the
material is subjected to a sinusoidal strain, i. e., e= e 0 coswt,
then the average heat generation rate per unit volume can be
expressed as follows:
In a computer program, it is not necessary to use Equation (12)
for calculations because one can use the following Equation (13)
to get the heat dissipated by each element in time Dt.
(8)
(9)
(10)
(11)
(12)
In the calculations one only needs to calculate until the system
reaches the steady state. In the steady state the energy
generated in each cycle should be the same. So one can then
use the energy generated in each cycle to see whether the
steady state has been achieved or not. When the steady state
has been reached the energy generated in one cycle is converted
into the heat generation rate per unit volume q*.
As the energy is dissipated in the web when the horn
vibrates, the web will get hotter and heat is conducted from
the hotter web to the relatively cooler horn, the anvil and the
surrounding air. Heat conduction is much greater than the
convective heat loss to the air. This is due to the greater heat
conductivity of the horn and anvil as compared with the low
heat transfer coefficient of air.
From the theory of heat transfer, one can get the following
general heat conduction Equation (14).
(14)
where r (kg/m 3 ) is the density of the material, cp (J/kg- o C)
is the heat capacity, k (W/m o C) is the conductivity, q* (W/m 3 )
is the internal heat generation rate per unit volume, T ( o C) is
the temperature and t (s) is the time.
In this problem one should simplify the heat conduction
equation so that one can get reasonable solutions easily. In
practical productions the anvil pattern has a certain width
which is at least a few millimeters long along the anvil longitudinal
direction. The pattern width is about ten times larger
than the gauge between the horn and anvil. Consequently the
end effects of the z direction which is in the longitudinal
direction of the anvil can be neglected. Therefore, we can just
consider the 2-dimensional problems as depicted by Equation
(15) and Figure 2.
(15)
The Compressional Behavior of Fiber Webs
The batt made by the Rando Webber Processor is quite
lofty. In order to calculate the initial force applied to the web
one should know the dynamic moduli and hypothetical height
h o of a web. The compressional behavior of fibrous masses
has been studied by several investigators [4, 7, 13, 22, 26, 28].
They have attempted to characterize the behavior through
simple mathematical models.
Van Wyk [28] proposed a relationship of pressure versus
volume (inverse-cube of volume) based on some fundamental
considerations of web structure and beam bending theory. He
considered fiber mass as a “system of bending units,” wherein
the constituent fibers are straight, randomly oriented, elastic
beams (or rods). Deformation of the system is assumed to
INJ Summer 2001 41

R h The radius of the small corner of
the horn. It is 1.96X10 -3 (m)
R a The radius of the anvil. It is
43.97X10 -3 (m)
W sh The width of the middle smooth
part of the horn tip 8.96X10 -3 (m)
h The gauge between the horn and
anvil (m)
T w The thickness of a web (m)
T ff The thickness of a nonwoven fabric
at point F (m)
x lth The x coordinate of the point
D where the web begins to touch
the horn (m)
x rth The x coordinate of the point
E where the web ends to touch
the horn (m)
w The anvil angular speed
(rad./sec)
Figure 2
THE OVERALL FINITE ELEMENT
DOMAIN OF A WEB
result from the bending of the units; no other modes of deformation
were considered. He derived the relationship between
stress and volume of the fiber mass as follows,
(16)
where K is a dimensionless constant determined by the
structure of the fiber mass, E f is the fiber elastic modulus, rf
is the fiber density, m is the fiber mass in volume V 0 . V 0 is the
initial volume, r 0 is the initial bulk density, V c is the compressed
volume, and r c is the bulk compressed density of the
fibrous assembly.
During compression the area of fibrous assembly can be
assumed to be constant. The initial height and the height
under compression are h o and h c , respectively. If h f is the
height and if the web had the same density as its component
fibers, then the elastic modulus, E w , of the web can be derived
as follows:
(17)
Therefore, the elastic modulus of the web is proportional to
its fiber elastic modulus. The web’s elastic modulus is also
related to the structure constant K and the web initial and
compressed heights.
Experimental studies based on the van Wyk model have
been attempted by several investigators. Dunlop [7] studied
the compression behavior of different wools. The compression
characteristics in the van Wyk's model are governed by
the parameters KE f and r 0 . In case of samples examined by
Dunlop, the parameter KE f showed a much stronger effect on
the compression characteristics of fiber webs.
Schoppee developed a new, relatively simple, predictive
model of the relationship between compressive stress and
thickness of fiber assembly for thick nonwoven materials that
have previously been consolidated at a high level of stress
[21]. The model assumes that the nonwoven fabric was originally
formed by a Poisson process in which individual fibers
were deposited on the plane independently and at random.
From the mathematics of the Poisson distribution, the probability
of n fibers overlapping, or stacking, in the thickness
direction of the fiber assembly can be defined at any point in
the plane in terms of the fiber dimensions, fiber density and
average weight per unit area of the assembly. When the
assembly is uniaxially compressed, those local areas where
the largest number of fibers overlap contribute first to the
total resistive force offered by the nonwoven. The total force
required to compress the assembly to a given thickness can be
expressed as the sum of the forces needed to reduce the thickness
of each individual stack of overlapping fiber mass to the
thickness of the assembly. The stress s(t) of the nonwoven at
any given thickness t can be written as:
(18)
Where, E fc is the fiber transverse compression modulus, A 0
is the cross sectional area of each column and it is assumed to
be very much smaller than the area of intersection between
two overlapping fibers (A 0

diameter, density and web structure.
The web static compressional behavior and the static tensile
behavior of fibers can be measured by using an Instron
Tensile Tester. Then, Cf(h) can be calculated easily. Similar
equations like Equation (19) are used for the relationship
between the web dynamic compressional behavior and fiber
dynamic tensile moduli as follows:
(20)
(21)
where E w ’ and E w ” are the dynamic elastic and loss moduli
of a web, respectively. E f ’ and E f ” are the dynamic elastic
and loss moduli of the fibers, respectively. Therefore, E w ’ and
E w ” can be calculated from the web’s static compressional
modulus, its fiber static tensile modulus, dynamic elastic and
loss moduli.
The web compression is highly nonlinear. In order to simplify
the problem the web compression can be represented as
composed of several linear stages. Each stage has its own
constant modulus, initial thickness and suitable range. So the
results in Equation (11) can be calculated.
Web Thermal Conductivity
Heat transfer of nonwovens is of considerable practical
significance, since it plays a major role in determining the
thermal comfort of these materials when used in applications
such as clothing and quilts. There are a lot of published
works that have reported the heat transfer and thermal conductivity
of webs, nonwoven fabrics, and batts, etc. [1, 3, 8,
18 and 29].
Woo et al. [29] proposed a model that accounts for air and
fiber thermal conduction through a nonwoven fabric. Their
model includes both fiber anisotropic and fabric orthotropic
effects and assumes net heat flow perpendicular to the fabric
plane. They derived a thermal conductivity equation that has
the following parameters: the fiber volume fraction,
anisotropy factor, the polar orientation parameter, fabric
thickness, and fiber diameter. Its validity is confirmed in
experiments that measure the thermal conductivity of various
nonwoven barrier fabrics.
Stanek and Smekal [23] derived a heat conductivity equation
of webs that involves the filling coefficient, structure
parameter, thickness, mean temperature, and fiber diameter.
The conductivity equation is complicated and the structure
parameter has to be chosen so that the calculation results have
the best agreement with experimental results.
Baxter [1] experimentally verified that the web conductivity
obeys the empirical Lees’ Equation (22) as follows:
(22)
where v f and v a are the fractional volumes of the fiber and
air, respectively; k f and k a are the fiber and air conductivities,
respectively; k m is the conductivity of the mixture. The shortcoming
of Equation (22) is obvious because it ignores all the
web and fiber structural parameters such as the fiber diameter
and orientation. But the advantages are also obvious
because it is very easy to apply to practical problems and it
takes the volume change into consideration. The volume
change is the major factor that influences the mixture conductivity.
Therefore in this research when the web moves
between the horn and anvil, it is accepted that the web conductivity
changes according to Equation (22).
Initial and Boundary Conditions
To solve the Equation (15), which is a 2-dimensional partial
differential problem, one needs to know the specification
of the initial condition at time t=t 0 on the domain area A and
of boundary conditions on the edge G for this problem [19].
The initial temperature field can be specified as
(23)
There are three kinds of typical boundary conditions
involved in this problem.
The first kind of condition is temperature condition. The
values of temperature at the boundary G T are specified.
These values may be constant or be allowed to vary with
time, i.e.,
(24)
The second kind of condition is heat flux. The values of
heat flux in the direction n normal to the boundary G q are prescribed
as q(x, y, t). Then we can write
(25)
The third kind of condition is convection. The convection
of heat in the direction n normal to the boundary G cv are written
as follows:
(26)
Here a is the heat transfer coefficient and T f is the fluid
temperature.
FEM Formulation
The two dimensional transient problem as depicted by
Equation (15) has to be solved to know the temperature
change in a web during a bonding process. In this research
finite element method (FEM) is used to solve Equation (15).
The expressions for the finite element characteristics may
be derived without actually specifying the type of element at
this point. However, the calculations were based on the fournode
rectangular element. The shape function matrix N is
given by
(27)
Where nen means the number of the element nodes. On an
INJ Summer 2001 43

element basis, the Galerkin method requires
(28)
(38)
It is emphasized that this integral applies to a typical element
e and the integration is to be performed over the area A e
of the element. After the Green-Gauss theorem, the second
kind of heat influx, and the third kind of convection boundary
conditions are applied, and we may get the following equation:
The Equation (29) is an unsteady heat transfer problem
which may also be referred to as a transient or time-dependent
problem. Since the time variable t enters into such a
problem we can use the partial discretization to separate the
space variables and the time variable. The unknown temperature
parameter function T within a typical element e can be
written as follows:
Here the N(x, y) is the shape function vector and d e is the
vector of the nodal temperatures for element e. It follows that
Equation (29) may be written as follows:
where
(29)
(30)
(31)
(32)
The element capacitance matrix is defined by,
(39)
(40)
Then the following element matrices K xxe ,K yye ,K cve ,f cve ,
f q*e ,f qe
, and C e can be calculated [19, 24]. The global stiffness
matrix K, capacitance matrix C, and the nodal force vector
f can be assembled from these element matrices and the
local destination array.
The Enforcement of the Essential Boundary
Conditions
In the boundary conditions mentioned earlier, there is a
kind of condition that has constant temperatures at these
boundaries. These constant temperature boundary conditions
must be enforced before the global matrices can be used to
solve the unknown temperatures. In the programs coded for
this research the above boundary conditions are enforced by
a method which is based on the concept of penalty functions
[24]. This method is easy to apply and understand.
After the application of the essential boundary conditions
we get the following global matrices: K a ,C a , and f a . Here the
superscript ( a ) is used to indicate the assemblage matrices
after the application of the essential boundary conditions.
Then we get the following equation to solve
(41)
Equation (41) needs to be solved for the nodal temperature
as a function of time. There are different schemes to solve this
equation. They may be summarized in one convenient equation
as follows:
(42)
The element stiffness matrices are in turn given by,
y
and the element nodal force vectors by,
44 INJ Summer 2001
(33)
(34)
(35)
(36)
(37)
where the parameter q takes on values of 0, 1/2 and 1 for
the forward, central, and backward difference schemes,
respectively. The value 2/3 is for the Galerkin method [24]
and q = 2/3 is particularly useful because it is more accurate
than the backward difference scheme (q =1) and more stable
than the central difference scheme (q = 1/2). So q = 2/3 is
used in the calculation.
The Geometry of the Finite Element Meshes
The overall domain of a web considered for the FEM calculation
is shown in Figure 2. The domain consists of three
different areas: the area ABCDIJA before entering the bonding
site, the area DEHID at the bonding site, and the area
EFGHE after exiting the bonding site.

The origin of the domain coordinate is the middle position
of the bonding site as shown in Figure 2. Then all the positions
of the edges ABCDEFGHIJA in Figure 2 can be calculated.
For the y coordinates of element nodes within the bonding
site DEHID are a bit complicated because the web is under
pressure and deformed. Right now one can just assume that
the moduli of the spunbonded fabric and batt are E s and E b ,
respectively; their initial heights are H s and H b ; their heights
after deformation are h s and h b . The distance between the
anvil and horn is h. Then one can get the following two equations:
(43)
(44)
A
The horn and anvil used in this research need to be
described first in order to calculate the sizes of the aforementioned
different areas. Figure 3 shows the front and side views
of the horn and anvil, respectively. The anvil pattern is quite
simple and is just a protruded ring over a roller. The radius of
the anvil for bonding R a , the radius of the small corner of the
horn R h , and the width of the middle smooth part of the horn
W sh are known as their values are shown in Figures 2 and 3.
The gauge g changes with the web unit area weight and processing
parameters such as pressure and speed. The web
thickness T w changes with the web unit area weight.
In the theoretical model there is an assumption that the web
properties such as the spring constant k and the damping coefficient
h are assumed to be constant and are independent of
temperature. So the web spring and damping coefficients do
not change at the bonding site. Therefore, the thickness of the
web at the exit of bonding site (the thickness at points E and
H as shown in Figure 2) does not change either and is the same
as the web thickness T w . Practically the bonded web (fabric)
thickness at the exit of bonding site is smaller than the thickness
at the entry of the bonding site because the web is under
the horn vibration and pressure and bonding can occur within
the web. Therefore the web properties can change and its
thickness can also change at the bonding site. After exiting
from the bonding site the bonded web cools down gradually
and the thickness also changes. The thickness of the fabric at
the wrapping roller of the ultrasonic machine is assumed to be
the same as the final thickness of the fabric, i. e., the thickness
of the fabric will not change after it reaches the wrapping
roller. Between the exit of the bonding site at point E and the
wrapping roller the fabric thickness is assumed to reduce linearly
due to draw (winding tension).The distance from the exit
of bonding at point E to the wrapping roller is 0.368 m.
B
Figure 3
HORN AND ANVIL SIZE (MM)
(A) FRONT VIEW; (B) SIDE VIEW
From the above two equations h s and h b can be calculated.
Because the height h s of the spunbonded fabric and h b of the
batt under deformation are divided evenly by their corresponding
element number N ehs and N ehb , respectively, one
can calculate the y coordinate for each node when one knows
the distance h between the anvil and horn. Therefore all the y
coordinates of the nodes within the bonding site DEHID can
be calculated.
One now needs to calculate the y coordinates of the nodes
within the area EFGHE. As previously mentioned, the fabric
thickness decreases linearly due to draw with the distance
from the exit of the bonding site. At the exit EF of the bonding
site, the heights h s and h b of the spunbonded fabric and
the batt are known. After exiting from the bonding site their
heights are assumed to decrease linearly, same as the bonded
fabric. Therefore one can calculate the heights of the spunbonded
fabric and the batt of the nonwoven fabric at any distance
from the position EH.
It can be easily shown that the vertical speed v p of the anvil
at the x coordinate x of the bonding site is
where w o is the circular speed of the anvil (rad./s).
(45)
Details of the Initial and Boundary Conditions
As previously mentioned one needs to know the specification
of the initial condition at time t=t 0 on the domain area A
and of the boundary condition on the edge G to solve
Equation (15). The initial conditions of the whole domain, as
shown in Figure 2, are that the temperatures of all the nodes
are at room temperature 20 o C at time t=0 and can be
expressed by the following equation.
(46)
The boundary conditions are described below in details.
The boundary G 1 (edge AB) is the leftmost edge of the
whole domain. Because of the low thermal conductivity of
the spunbonded fabric and the batt and the low temperature at
INJ Summer 2001 45

the position DI the temperature at G 1 is not affected by the
bonding process. Therefore, the temperature at the boundary
G 1 stays at room temperature, i.e.,
(47)
The boundaries G 2 (edge BCD) and G 8 (edge AJ) have the
convection type condition, i. e.,
(48)
In this case T f is the room temperature again which is 20 o C.
a is 15 [5].
The boundary G 5 (edge FG) has the heat flux type condition.
In this research the length L fl from the exit (position EH)
to the edge FG used for the calculation is about 0.063m. From
the experimental measurements the temperature change normal
to the edge FG is rather small. So it is assumed that there
is no heat loss at this position, i.e.,
(49)
The boundaries G 4 (edge EF) and G 6 (edge GH) have the
convection type condition, i. e.,
(50)
In this case T f is the room temperature and is 20 o C, also.
But a is a bit complicated because it is related to the air
speed, the thickness of the fabric, and the temperature of the
bonded fabric. The fan behind the horn was turned on to help
get rid of heat to keep the horn cool. So the air speed close to
the horn was affected by the fan and changed with the distance
from the bonding site. The thickness of the fabric and
temperature of the bonded fabric also changed with the distance
from the bonding site. All of those changes would cause
a to change with the distance from the exit of the bonding
site. Therefore, a constant value for a was not a good choice.
So a was calculated from the experimental measurements of
temperature. It was found that a could be approximated by
two linear lines with the distance from the exit of the bonding
sites for G 4 and G 6 . There were specific values for a that are
reported in Part 2 of this paper.
The boundary conditions for G 3 and G 7 were a bit difficult.
The simple insulator or the infinite conductivities of the horn
and anvil did not give good results. A close look at the experimental
results showed that the temperatures could be approximated
by several line segments and their temperature related
to temperature T k of the middle point K at the bonding exit.
Figure 4 shows the approximation for G 3 and G 7 . Both the y
coordinates were normalized by T k . The x coordinates were
normalized by the distance of DE and JH for G 3 and G 7 ,
respectively. The position labeled 1 was the same as the origin
0 of the coordinate system in Figure 4. The position 1 and
4 in Figure 4 (A) corresponded to D and E in Figure 2. The
position 1 and 5 in Figure 4 (B) corresponded to J and H in
Figure 2. The specific values for TT2, TT3, XT2, and XT3, etc.
46 INJ Summer 2001
Figure 4
THE TEMPERATURE APPROXIMATION
FOR (A)G 3 ; (B) G 7
are given in Part 2 of this paper.
Matlab was the language chosen for computer code. The
overall procedures to solve this problem are as follows. The
element node coordinates were calculated first. The element
stiffness matrix, force matrix and capacitance matrix were
then calculated. Subsequently, their corresponding global
matrices were assembled.
The heat generation was calculated. Every node was given
its initial temperature condition. Then the temperature type
boundary conditions were applied by the penalty method.
Equation (41) was solved. After some time at one position the
web moved one small step forward. Then the boundary conditions
were updated and Equation (41) was solved again. At
the end of each step the final result was compared to the final
result of the last step. This process was continued until the
error limits between the results of the last two steps were
within a certain limit. In this research the limit was set at
0.1%.

Verification of the model and the experimental results of
heat generation during ultrasonic bonding are discussed in
Part 2 of this paper.
Literature Cited
1. Baxer, S., “Thermal Conductivity of Textiles,”
Proceedings of Physical Society, London, Vol. 58, 1946,
p.105.
2. Benatar, A. and Gutoski, T., “Ultrasonic Welding of
PEEK Graphite APC-2 Composites,” Polymer Engineering
and Science, Vol.29, No.23, 1989, p.1705.
3. Bomberg, M., and Klarsfeld, S., “Semi-Empirical Model
of Heat Transfer in Dry Mineral Fiber Insulations,” Journal
of Thermal Insulation, Vol. 6, 1993, p.156.
4. Carnaby, G.A., “The Compression of Fibrous
Assemblies with Applications to Yarn Mechanics,”
Mechanics of Flexible Fiber Assemblies, Sijthoff and
Noordhoff, Alphen aan den Rijn, The Netherlands;
Germantown, Maryland, U. S. A., 1980.
5. Chapman, A.J., Fundamentals of Heat Transfer, New
York: Macmillan Publishing Company, 1987.
6. Chernyak, B. Ya., et al., “The Process of Heat Formation
in the Ultrasonic Welding of Plastics,” Welding Production,
Vol. 2, August, 1973, p. 87.
7. Dunlop, J.I., “Characterizing the Compression
Properties of Fiber Masses,” Journal of Textile Institute, Vol.
65, 532, 1974, p.532.
8. Epps H.H., “Effect of Fabric Structure on Insulation
Properties of Multiple Layers of Thermally Bonded
Nonwovens,” INDA Journal of Nonwovens Research, Vol. 3,
No. 2, 1991, p.16.
9. Flood, G., “Ultrasonic Bonding of Nonwovens,” Tappi
Journal, May, 1989, p.165.
10. Flood, G., “Ultrasonic Energy, a Process for
Laminating Bonding Nonwoven Web Structure,” Journal of
Coated Fabrics, vol. 14, Oct., 1984, p.71.
11. Flood, G., “Ultrasonic Bonding of Nonwovens,” 1988
Nonwovens Conference, p.75.
12. Floyd, K. and Ozsanlav, V., “Application of
Ultrasonics in the Nonwoven Industry,” EDANA's 1988
Nordic Nonwovens Symposium, p.120.
13. Hearne, E.R., and Nossar, M.S., “Behavior of Loose
Fibrous Beds During Centrifuging, Part I: Compressibility of
Fibrous Beds Subjected to Centrifugal Forces,” Textile
Research Journal, Vol. 52, October, 1982, p.609.
14. Huang H. and Usmani, Finite Element Analysis for
Heat Transfer, Springer-Verlag London Limited, 1994.
15. Leverkusen W. Land, “Investigations into the Process of
Ultrasonic Welding,” Kunststoffe, Vol. 68, No. 4, 1978, pp. 16-18.
16. Matsyuk, L.N. and Bigdashevskii, A.V., “Ultrasonic
Welding of Polymeric Materials,” Soviet Plastics, Vol. 2,
1960, p. 70.
17. Mueller, D. and Klocker, S., “Development of a
Complete Process Model for Nonwovens Thermal Bonding,”
International Nonwovens Journal, Vol. 6, No. 1, 1994, p.47.
18. Obendorf S.K., and Smith J.P., “Heat Transfer
Characteristics of Nonwoven Insulating Materials,” Textile
Research Journal, Vol. 56, 1986, p.691.
19. Reddy, J.N., An Introduction to the Finite Element
Method, McGraw-Hill, Inc., 1993.
20. Rust, J.P., “Effect of Production Variables on
Properties of Ultrasonically Bonded Nonwovens,” M.S.
Thesis, School of Textiles, Fiber and Polymer Science,
Clesmon University, 1985.
21. Schoppee, M.M., “A Poission Model of Nonwoven
Fiber Assemblies in Compression at High Stress,” Textile
Research Journal, Vol. 68, 1998, p.371.
22. Sebestyen, E., and Hickie, T. S., “The Effect of Certain
Fiber Parameters on the Compressibility of Wool,” Journal of
Textile Institute, Vol. 62, 1971, p.545.
23. Stanek, L.H. and Smekal, J., “Theoretical and
Experimental Analysis of Heat Conductivity for Nonwoven
Fabrics,” INDA Journal of Nonwovens Research, Vol. 3,
No.3, 1991, p.30.
24. Stasa, F.L., Applied Finite Element Analysis for
Engineers, New York: Holt, Rinehart and Winston,1985.
25. Tolunay, M.N., Dawson, P.R., and Wang, K.K.,
“Heating and Bonding Mechanisms in Ultrasonic Welding of
Thermoplastics,” Polymer Engineering and Science, Vol. 23,
No. 13, Sept. 1983, pp.726-733.
26. Udomkichdecha, W., “On the Compressional Behavior
of Bulky-fiber Webs (Nonwovens),” Dissertation, NCSU,
1986.
27. Volterra, E. and Zachmanoglou, E.C., Dynamics of
Vibrations, Ohio: Charles E. Merrill Books, Inc., 1965.
28. Van Wyk, C.M., “Note on the Compressibility of
Wool,” Journal of Textile Institute, Vol. 37, 1946, T285.
29. Woo, S.S., Shalev I., and Barker, R., “Heat Moisture
Transfer Through Nonwoven Fabrics Part I: Heat Transfer,”
Textile Research Journal, Vol. 64, 1994, p.149.
30. Wool, R.P. and O’Connor, K.M., “A Theory of Crack
Healing in Polymers,” Journal of Applied Physics, Vol. 52,
No. 10, Oct., 1981.
— INJ
INJ Summer 2001 47

INJ DEPARTMENTS
NONWOVEN
PATENT REVIEW
48 INJ Summer 2001
Jeopardizing the
Patent Application
Early in the career of every good
product development researcher an
important lesson is learned. This lesson
centers on the rule of law that “a new
patentable product must not be offered
or sold in commerce until the patent
application is filed.”
The basis for this rule is known as
Section 102 of the Patent Act. The rule
precludes an inventor from obtaining a
patent if the invention was on sale or
offered for sale in the United States
more than one year before a patent
application is filed. The justification for
’102 is the premise that prompt and
widespread disclosure is basic to the
concept of granting a monopoly. The
time provided the inventor is deemed to
be adequate and reasonable for determining
whether seeking a patent is
worthwhile.
The problem arises in defining the
specifics of the “on-sale bar.” Is one
offer of sale sufficient? Does the sale of
an experimental sample start the clock?
Does showing a sample and discussing
eventual production constitute an offering?
In a decision by the U.S. Supreme
Court, more concrete guidelines have
been provided for precisely determining
when the one-year clock is started. This
decision [Pfaff v. Wells Electronics,
Inc.; 119 S. Ct 304 (1998)] outlined a
new test for determining when an application
must be filed if the concept is to
be patented.
The previous ruling was that a concept
must be “substantially complete”
at the moment that the one-year period
begins. Again, this standard can be subject
to a great deal of uncertainty. As a
result, the Court ruled that (1) the invention
must be complete, as indicated by
the fact that the invention if ready for
patenting; (2) the invention must be the
subject of a commercial offer for sale.
Establishing that the invention is ready
for patenting depends on one of two
potential tests:
• Reduction to practice, as indicated
by a physical embodiment of the invention,
• Showing that more than one year
before filing a patent application the
inventor had prepared drawings and
other description of the invention that
were sufficiently specific to enable a
person skilled in the art to practice the
invention.
The Court also stated that an inventor
is entitled to perfect the invention
through experimentation without loss of
the right to obtain a patent. If an activity
was actually experimental rather than
commercial, a patent can be sought.
As usual, carefully documented and
timely records that establish the progression
of the experimental stage are
very important to obtaining the protection
of the ruling. The U.S. Patent and
Trademark Office requires disclosure of
any information that may be deemed
material to the patentability of the
invention. If this is not fully carried out,
a patent may be unenforceable on the
grounds that all relevant material information
was not disclosed to the PTO.
This is a case where you must testify
against yourself if there was anything
that can be construed as a commercial
offering.
Consequently, to build a strong patent
estate a company and the inventor must
pay close attention to the following
guidelines:
• File the application as early as pos-
YOUTHFUL INVENTORS
How old does a person have to be to become an inventor? One group convinced
that innovative talents exist even within young children is the U.S.
Patent Model Foundation, a non-profit organization based in Alexandria, VA.
This group of educators, inventors, parents and others feel that with a little
encouragement school-age children can do a remarkable job of meeting needs
with new inventions.
The organization conducts a broad spectrum of activities, ranging from supplying
school teachers and parents with ideas and materials to foster innovation
amongst children to sponsoring an annual contest for youthful inventors. The
contest is conducted according to the age of the participants. Selection of the
winners is made by a panel of high-ranking executives of major companies, as
well as scientists and educators. Last year’s panel included a Nobel Prize
Laureate.
Recent inventions that won monetary awards for the youthful participants
included a mobile rabbit house, a snorer’s solution, pick-up truck rails, a paw
cleaner, and self-extinguishing safety candles. A fifth-grader won a prize for a
circular device that fits at the bottom of a beverage cooler, so that elusive last
drop in the container can be obtained.
This effort was initiated in the 1980’s to rekindle the American inventive spirit.
Take a look at their website (www.inventamerica.org). Also, the USPTO now
has a special page for youthful inventors that provides some help and insight to
their interests (www.uspto.gov/go/kids/). Further, a website devoted to debunking
commercial groups that profess to aid would-be inventors at a rather extravagant
fee also has a section devoted to kid inventors (www.inventored.org).

PATENT REVIEW
sible; ensure that no commercial offering
is made more than one year before
application if the invention is ready for
patenting.
• Experimentation done to perfect the
invention must be carefully documented.
• Any improvements or modifications
after the offer to sell should be thoroughly
documented; also, such
improvements should be claimed in the
patent application.
• Fully disclose to the USPTO any
commercial activities involving the
invention that occurred before the oneyear
period commenced.
• Carefully coordinate the activities of
the R&D Department and the Marketing
Department to ensure that no breaches
of the one-year ruling occur.
NONWOVEN PATENTS
Disposable PLA Composition with
Good Processability
Easy disposability of sanitary personal
care products is a product feature that
has been sought for many years. With
the growing concern for solid waste
management and the increasing influence
of sound ecological practices, this
search has been intensified.
Easy disposability can mean different
concepts to differing groups. It may
mean realistic flushability in some areas
and with some products. Accelerated
biodegradation may be the goal in some
cases. Acceptable compostability under
the appropriate conditions may be adequate
in some quarters.
Polylactic acid (PLA) polymers have
been viewed as an answer to these needs
and considerable R&D work has been
and is currently being expended on this
polymer system. Problems have been
encountered with such degradable
mono-component fibers and materials,
however. As pointed out by the patent
disclosure, such known degradable
fibers typically do not have good thermal
dimensional stability, such that the
fibers usually undergo severe heatshrinkage
due to the polymer chain
relaxation during downstream heat
treatment processes, such as thermal
bonding or lamination.
PLA polymers are known to have a
relatively slow crystallization rate as
compared to polyolefin polymers, thereby
often resulting in poor processability
of the aliphatic polyester polymers due
to the relaxation of the polymer chain
during such downstream heat treatment
processes. An additional heat setting
step can be used, but this often limits the
use of the fiber for integrated nonwoven
processes. This patent provides a thermoplastic
composition which exhibits
desired fiber and nonwoven processability,
liquid wettability, and thermal
dimensional-stability properties. The
invention is claimed to also provide a
fiber or nonwoven structure that is readily
degradable in the environment.
The thermoplastic composition disclosed
consists of a mixture of a first
component, a second component, and a
third component, comprising an unreacted
mixture of a poly(lactic acid)
polymer; a polybutylene succinate polymer
or a polybutylene succinate adipate
polymer, or a mixture of the two latter
polymers, plus a wetting agent for the
three constituent polymers or mixtures.
It has been discovered that by using this
thermoplastic composition, fibers and
nonwovens are obtainable that are substantially
degradable, yet the composition
is easily processed into fibers and
nonwoven structures that exhibit effective
fibrous mechanical properties.
The PLA polymer can be prepared by
either the polymerization of lactic acid
(various enantiomorphs) or from the corresponding
lactide. By modifying the
stereochemistry of the PLA polymer, it is
possible to control the melting temperature,
melt rheology, and crystallinity of
the polymer. By being able to control
such properties, it is possible to prepare a
thermoplastic composition and a multicomponent
fiber exhibiting desired melt
strength, mechanical properties, softness,
and processability properties so as to be
able to make attenuated, heat-set, and
crimped fibers and nonwoven fabrics.
The second component in the thermoplastic
composition is a polybutylene
succinate polymer, a polybutylene succinate
adipate polymer, or a mixture of
such polymers. A linear version rather
than a long-chain branched version of
this component is desired. The PLA
polymer is best used in an amount
between 15 weight % to about 85
weight %. The amount of the other two
polymers used in the unreactive mixture
is selected to provide a composition
exhibiting the desired processing and
end-use properties. Further, the amount
and composition of the wetting agent is
selected to provided adequate rewetting
properties to the fiber or nonwoven,
without detracting from the processability
of the composition. It is indicated
that the composition is very suitable for
nonwoven extrusion processes such as
the spunbond or meltblown processes.
U.S. 6,211,294 (April 3, 2001); filed
December 29, 1998. “Multicomponent
fiber prepared from a thermoplastic
composition.” Assignee: Kimberly-
Clark Worldwide, Inc. Inventors; Fu-
Jya Tsai, Brian T. Etzel.
Insulation Panel with Meltblown
Microfiber Acoustical Absorbing
Fabric
Various materials and structure have
been developed to reduce sound transfer.
The sound absorption characteristics
of porous insulation materials is a function
of the acoustic impedance of the
material.
Acoustic impedance consists of frequency
dependent components, including
acoustic resistance and acoustic
reactance. Acoustic reactance depends
largely on the thickness of the product
and material, and to a lesser extent on
the mass per unit area of an air permeable
facing or film which may be
applied over the surface of the porous
insulation material. On the other hand,
acoustic resistance depends on the air
flow resistance of the porous insulation
material.
As indicated, these components of
acoustic impedance are dependent upon
the frequency of the sound.
A variety of materials and configura-
INJ Summer 2001 49

PATENT REVIEW
tions have been proposed to obtain the
appropriate acoustical insulation properties
and to control such properties.
Prior patent art covers a broad selection
of such materials and configurations to
enhance the sound absorption performance
of various products and systems.
The present invention comprises an
inner core including a plurality of cells,
with an outer membrane disposed on at
least one side of the inner core to form a
number of sound attenuating chambers.
The inner core can be formed from such
cellular materials as a honeycomb, or
egg-crate material or open-celled foam
of appropriate composition. The outer
membrane or covering of the cellular
layer comprises an inner substrate of
nonwoven meltblown microfiber
acoustical absorbing fabric, and an
outer layer of a decorative fabric or film
to also protect the inner substrate of
meltblown fabric.
The meltblown layer comprises a
layer of fine or superfine thermoplastic
fibers, which extend into the cellular
inner core. Bonding of the outer membrane
to the inner core is accomplished
under pressure and temperature, forming
a plurality of tuft-and-fabric elements or
buttons in each cell, which provides the
superior sound absorbing feature.
So fabricated, the acoustical insulation
panel is suitable for use as acoustical
wall panels, ceiling panels and office
partitions, automotive headliners and
hoodliners, liners for heating, ventilating
and air conditioning systems, appliance
insulation and similar such applications.
U.S. 6,220,388 (April 24, 2001); filed
January 27, 2000. “Acoustical insulation
panel.” Assignee: Strandtek
International, Inc. Inventor: David M.
Sanborn.
50 INJ Summer 2001
Nonwoven Triboelectric Filter
Medium
With the increasing demands for
clean air under a widening variety of
conditions and environments, pressure
is mounting on air filter technologists to
solve increasingly difficult filtration
problems. Concern with ever-decreasing
particle size into the submicron
range, along with the demand for very
low pressure drop performance, coupled
with limited fan capabilities and highly
limiting space constraints, all propel the
requirements to ever greater levels of
performance.
Typically, this has meant certain performance
trade-offs. One of the most
fundamental of filtration trade-offs is
between particle capture efficiency on
the one hand, and pressure drop on the
other. It is well recognized that the less
obtrusive the filtration media is to air
flow, the higher the flow output from
the system into which the filter is
installed. Filtration efficiency must
often be compromised to keep flow
within acceptable limits to obtain satisfactory
air system performance.
The use of electrostatics has provided
some improvement in air filter media.
With the fiber carrying an electrostatic
charge of opposite polarity to that commonly
carried by fine dust particles,
electrostatic charge forces can act to
attract the fine particles to the fibers and
to impact capture. In practice, these
media have been found to lose their
effectiveness as a function of time.
In certain instances, this can occur
rapidly, in the space of just days or
weeks, particularly on exposure to elevated
humidity and temperature, or on
exposure to certain classes of aerosols,
such as oily aerosols.
The use of very thin media of low
basis weight, comprising fine fibers in
the range of 1 to 5 microns can significantly
lower this tendency while still
respecting the pressure drop demand,
but at the expense of low loading capacity
and thus much shortened filter life
relative to the coarse fiber approach.
A composite nonwoven filtration
medium which provides for improved
capacity with stable filtration characteristics
is disclosed in this patent. The
composite comprises a blended fiber
web prepared from two different fibers
selected to be of substantially different
triboelectric nature; the triboelectric
nature of a fiber is dependent upon
whether the fiber normally carries a surface
rich in electrons or protons. Fibers
(synthetic and natural) can be arranged
in a spectrum of varying polarity, from
very positive to very negative as to their
triboelectric nature. By selecting fibers
of substantially different triboelectric
nature, a maximum of electrostatic
charge force is obtained.
In the disclosed composite filter medium,
the web of mixed fibers with widely
differing triboelectric potential provides
excellent electrostatic capture of
the very fine particles. This mixed fiber
web is combined with a layer of SM
material, having meltblown fibers on
one side and spunbond fibers on the
other. The SM fabric is positioned with
the meltblown fiber side next to the
mixed fiber web. A plastic netting material
is positioned between the two webs,
and then the entire composite is subjected
to needlepunch bonding. Alternately,
the mixed fiber web can be laid on the
meltblown side of the SM web, the combination
can be needled, and the this
combined web can be laid on the plastic
netting with the mixed fiber triboelectric
material side contacting the netting, followed
by entangling the material via
needling to combine the combination.
The base materials employed in the
manufacture of the composite filtration
medium includes a first layer of the
mixed fiber material formed from an
approximately 50%/50% mixture of
modacrylic and polypropylene fibers,
preferably having 15 to 20 microns
average fiber diameter. The fiber ratio
can actually from 40:60 to 70:30. This
first layer has a weight of 35 to 100
gram/square meter. Prior to mixing, the
fibers are scoured to remove all surface
contamination, to enable formation of a
stable triboelectric charge. This mixture
provides a high, stable positive charge
and a high, stable negative charge on a
microscopic level, along with overall
electrical neutrality. The mixture of the
two materials becomes electrically
charged during the nonwoven manufacturing
process. Filtration efficiency is
particularly enhanced by electrical
charges on the fiber for capturing submicron
sized particles. Other fibers of

PATENT REVIEW
PATENT GUIDELINES
Anyone who works with patents
and the patenting process knows that
this arena is complex and confusing.
In an attempt to provide some clarity,
if not succinctness, the USPTO
has published the finalized version
of its “Utility Examination
Guidelines.” This is being used by
PTO examiners to check applications
for compliance with patent
statues. Applicable to all areas of
technology, the new guidelines are
especially relevant in areas of
emerging technologies, such as
gene-related technologies. This is an
area, along with Internet patents,
were the PTO has been severely criticized
for granting allowance on
claims that many feel are completely
outside the purview of innovation.
The full text of the Guidelines can
be reviewed at the USPTO website
(www.uspto.gov).
widely differing triboelectric potential
may also be employed, including polyolefin/polyvinyl
chloride fiber, as well
as others.
The SM fabric used in the manufacture
of the composite filter media is a
polypropylene meltblown web having a
weight of between 5 to 10 gram/square
meter (gsm) and an average fiber size in
the range of 1 to 5 microns. A spunbond
fabric in this layer preferably comprises
a polyester or polypropylene spunbond
material having a weight of approximately
10 to 16 gsm.
The plastic netting in the composite
medium comprises an extruded
polypropylene netting, although polyethylene
or nylon plastic netting can
also be employed. Various net configurations
can be employed; good results
have been observed with a 0.033 inch
thick netting, having filaments arrayed
in a diamond shaped pattern with a filament
intersection angle of 85 to 88
degrees, and 19 to 20 strands per inch
filament count in either direction.
As preferably carried out, the netting
is located in the middle of the composite,
with the spunbond sheet on one
side, and the mixed fiber and a portion
of the meltblown needled through on
the other side of the netting.
The needling step not only joins the
materials but also further increases the
permeability of the finished media.
After the first needling operation, a
Frazier permeability rating in the order
of 170-220 CFM is observed when
combining 70 gsm of mixed fiber material
with a 5 gsm web of meltblown.
However, after the second needling
operation, the Frazier permeability rating
is observed to improve to 330-350
CFM. At the same time, the netting has
imparted to the composite media the
ability to be pleated as well as added
tensile strength to the media.
U.S. 6,211,100 (April 3, 2001); filed
April 30, 1996. “Synthetic filter media.”
Assignee: Minnesota Mining and
Manufacturing Company. Inventor:
Pierre Legare.
Nonwoven loop material for hookand-loop
fastener
Hook-and-loop fasteners are used when
it is desirable to create a refastenable bond
between two or more surfaces, such as in
clothing or disposable absorbent articles.
These fasteners are used in place of buttons,
snaps or zippers.
In general, hook-and-loop fasteners
have a male component and female
component. The female component
contains numerous upstanding loops on
its surface while the male component
contains hooks that mechanically
engage the female loops, thereby creating
a refastenable bond.
The male component contains a plurality
of resilient, upstanding hookshaped
elements. When the male component
and the female component are
pressed together in a face-to-face relationship
to close the fastening device,
the male component hooks entangle the
female component loops, forming a plurality
of mechanical bonds between the
individual hooks and loops. When these
bonds have been created, the components
will not generally disengage
under normal conditions. This is
because it is very difficult to separate
the components by attempting to disengage
all the hooks at once. However,
when a gradual peeling force is applied
to the components, disengagement can
be easily effected. Under a peeling
force, since the hooks are comprised of
a resilient material, they will readily
open to release the loops.
The manufacture of this type of closure
device is relatively costly.
Conventional hook-and-loop components
are typically formed by making a
woven fabric, with a number of woven
loops extending outwardly from a backing.
The loops may be provided by
weaving a base fabric containing supplementary
threads to form the loops, or
by knitting the loops into a fabric. In
other hook-and-loop components, the
loops may be formed by pleating or corrugating
processes. The male components
of such fastening devices are typically
formed by inserting stiff, resilient
monofilaments into the male component
and then subsequently cutting the
loops. The cut loops of the resilient
material serve as the hooks of the male
component.
These processes generally produce
costly hook and loop fastening materials
because they are relatively slow.
Also, the hook-and-loop components of
such fastening devices are usually made
out of relatively expensive material.
Further, the loops tend to have a
directional preference, thereby making
insertion of the hooks into the loops
more difficult, as the loops manufactured
using conventional methods may
tend to lay in one direction such that
hooks that point in a different direction
will be less likely to engage the loops.
This patent discloses a generalized
process for making the female loop
component of this type of mechanical
fastener via a nonwoven process. The
technique is to stretch the nonwoven
web in the machine direction (MD),
which causes a majority of the fibers in
the web to orient in the MD. The web is
then stretched in the cross direction
(CD), The fibers aligned in the MD are
caused to buckle somewhat and tend to
INJ Summer 2001 51

PATENT REVIEW
form a loop. The nonwoven web is then
subjected to a flow of hot air through
the web, which tends to heat-set the
loops on the side of the fabric away
from the entering air.
The process can be applied to various
nonwoven webs, such as spunbond,
hydroentangled, needled webs and laminated
combinations of these. However,
the inventor prefers to use meltblown
nonwoven webs, especially meltblown
webs that are fuse bonded during preparation,
or by fiber entanglement during
formation, or by thermal point calendering
techniques.
In the method disclosed, the nonwoven
web is first stretched in the MD
approximately 30 to 80%. The web is
then stretched in the CD in a stretch
range of 70 to 150%. The inventor also
points out that the stretching can be
skewed. The web is then treated to high
velocity air (50 to 120 psi) blown
through the back of the nonwoven web;
this causes the looped fibers to protrude
in the “z” direction and also stabilizes
that configuration.
Another variation of the disclosed
generalized process can involve a spunbond
nonwoven fabric give the two-step
stretching process, followed by the high
velocity, hot air stabilization and looping
step; the inventor then points out that
such a loop fabric can be further
improved and stabilized by coating the
non-loop side of the fabric with a meltblown
layer. Also, this coating treatment
can be done following the stretching
step and before the hot air loop-raising
step. Other variations of the process are
also revealed in the patent disclosure.
U.S. 6,214,693 (April 17, 2001); filed
July 30, 1999. Assignee: YKK
Corporation of America. Inventor:
Matthew C. Pelham.
Thermal Wound Dressing
For many years the presence of
warmth at a wound site has been known
to have beneficial effects in the healing
of the wound. It is well known and documented
that raising tissue temperature
causes dilation of the arterial blood vessels
that pervade wounds, which in turn
results in increased oxygen delivery to
these wounds, thus accelerating the
repair of the tissues. In particular, the
presence of controlled heat, (preferably
around 5 0 C above body core temperature),
seems to enhance the quality and
rate of wound healing in various wound
types. This appears to be true for partial
thickness types to full thickness
wounds, in either a clean or infected
state.
Unfortunately, heat therapy for the
treatment of wounds, either infected or
clean, is extremely difficult to achieve in
practice. Devices of various forms have
been used, but these can result in wound
drying or dessication and consequent
retardation of the healing mechanisms.
Burning of wound sites can also occur.
Efforts have been made over the years
to provide devices to control more
closely the necessary elevated temperatures
required for optimum wound healing.
A variety of devices have been proposed,
but these devices are all fairly
complex and not compatible with
wound care in a healthcare facility or
the like. Furthermore, such devices are
expensive and not fully proven to be
effective in promoting good wound
repair. Also, such devices purely
address the wound site. Vascular dilation,
the essence of heated wound
repair, needs to take place where blood
vessels enter and leave the wound site.
The current disclosure involves the
use of a “rubefacient” or material that
may cause reddening of the skin and
give the feeling of warmth. Such a
material can permeate through the epidermis
and act to dilate the blood vessels
leading to and from the wound site.
This action simulates an elevated temperature,
leading to enhanced blood
flow. Such increased flow stimulates
healing, and also helps to removes catabolic
products, thus further contributing
to the wound healing process.
A suitable rubefacient is applied by
way of a nonwoven dressing matrix.
The nonwoven dressing must be of a
special configuration, to avoid the presence
of rubefacient in the wound itself,
as such would be extremely painful to
the patient if this material enters the
would area.
A variety of nonwoven wound dressing
configurations is suggested to surround
the wound site with the rubefacient
to obtain the beneficial effect,
while ensuring that none of the material
gets onto the wound itself.
The choice of rubefacient is important
in optimizing the dilation of the
blood vessels leading to and from the
woundsite. A well known rubefacient is
methyl salicylate (oil of wintergreen),
which is safe and well proven. A further
advantage to this substance is its resistance
without deterioration to steam
autoclaving and other sterilization techniques.
Other appropriate rubefacients
can include but are not limited to capsaicin,
Cayenne pepper, nonivamide or
benzyl nicotinate.
As already stressed, it is important to
avoid rubefacient migration into the
wound site. This can be achieved by
the design of the nonwoven dressing,
or the use of baffles to retain the rubefacient
away from the wound site, or to
maintain a “free area” between the
rubefacient and the wound site of sufficient
size to prevent migration during
dressing application or during its period
of patient use. Incorporation of the
rubefacient within the nonwoven
dressing or adhesive can secure its
positioning.
Another version of a suitable dressing
allows for the incorporation of rubefacient
within an adhesive matrix by
micro-encapsulation technology, such
that during dressing application, the
rubefacient is released and hence can
permeate the epidermal tissue and facilitate
vascular dilation. A further version
of this approach allows for timed
release of the rubefacient by using different
microencapsulating polymers
within the nonwoven dressing, such that
release of the rubefacient occurs over a
controlled period of time.
EP 1097682 (May 9, 2001); filed
November 30, 2000. “Wound
Dressing.” Assignee: Lohmann GMBH
& Co. KG. Inventors: Arno Max
Basedow, Edmund Hugh Carus. — INJ
52 INJ Summer 2001

INJ DEPARTMENTS
WORLDWIDE
ABSTRACTS AND
REVIEWS
A sampling of Nonwovens Abstracts from Pira International —
A unique intelligence service for the nonwovens industry
Paper and nonwoven teabags
The development of teabags since
1908 is reviewed. Teabag papers and
nonwoven tissues are now produced on
Maschinenfabrik Fleissner machines
using wet-laid techniques on inclined
wires. Initial 300%-400% moisture levels
are reduced on screen drum dryers
followed by steam-heated cylinders. The
fiber layer in teabag papers is sealed on
air flow I-drum dryers. Water jet bonded
nonwovens, now used for larger portion
teabags, are produced on Fleissner
AquaJet Spunlace equipment.
Author: Anon
Source: Allg. Vliesstoff-Rep.
Issue: no. 6, 2000, p. 39 (P) (In
German)
Natural thermosets
Crosslinked materials based on gelatine
can now be made which have the
properties of existing thermosetting
polymers and are biologically degradable.
Blends of gelatine with linseed oil
have been investigated to achieve new
hardening possibilities and decrease the
water absorption of gelatine. The blends
are compatibilised using a phase mediator
such as vegetable lecithin.
Gelatine/linseed oil blends can be made
into composites with fiber reinforcements
such as flax. In tests, the biological
degradability of gelatine based thermoplastics
has been shown to reach
DIN54900 standards. (3 fig)
Author: Braun D; Braun A
Source: Kunstst. Plast Eur.
Issue: vol. 91, no. 2, Feb. 2001, pp 36-
38
Aerodynamic web formation for the
creation of new nonwoven structures
A new procedure has been devised for
aerodynamic web formation, which is
characterised by intensive fiber opening,
reduced flow velocities and an increased
surface for fiber collection. To test the
principle, a discontinuous operating laboratory
unit has been built at the Institut
fur Textiltechnik der RWTH, Aachen,
Germany. Flow data and velocity distribution
measurements are made and
manufactured web samples investigated
regarding mass per unit, thickness, elasticity,
air permeability and fiber orientation.
The web evennness is improved by
increasing the opening degree and
decreasing electrostatic charge. Further
tests show the procedure to be suitable
for making prefabricated webs, sandwich
and composite structures. (4 fig, 7
ref)
Author: Paschen A; Wulfhorst B
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, pp 13-
14, 15
Hygiene and care: nonwovens as
problem solvers
Overall global cellulose fiber production
has swung around 2.7tpy since
1991, according to speakers at the 15th
Hof Nonwovens seminar. Nonwovens’
share of the West European market has
increased steadily over the period. In
1999 polypropylene accounted for 46%
of the West European drylaid nonwovens
sector, with 26% for polyester. The
70,200t demand for viscose amounted to
19% of this sector. Viscose has a small
share of the growing diaper, incontinence
and feminine hygiene market,
with stronger representation in the
household and medical wet wipes sector,
currently growing at 15% a year.
Technical developments in the spunlace,
water jet, interspun and dry lamination
processes are reviewed. (2 fig)
Author: Anon
Source: Allg. Vliesstoff-Rep.
Issue: no. 1, 2001, pp 24-25 (In
German)
Production and processing of Tencel
The development, processes, properties
and advantages of Tencel lyocell
fiber are described. Tencel, a synthetic
cellulose fiber, is manufactured by a solvent-spinning
method using N-methylmorpholine-N-oxide
(NMMO). The
method is described. It is environmentally
safe and allows total recycling of
the solvent. Primary fibrillation, enzyme
cleaning and secondary fibrillation produce
the peach skin effect characteristic
of the finished fabric. Chemical processes,
pre-treatments and dyeing methods
are outlined. Tencel combines the comfort
of natural fibers with the strength of
synthetics, and can withstand rigorous
processing. It is suitable for hydroentangled
and thermal bonded nonwovens,
and works well in blends with natural
and manmade fibers. The fiber is
biodegradable. (37 ref)
Author: Teli MD; Paul R; Pardeshi P D
Source: Indian Text. J.
Issue: vol. 110, no. 12, Sept. 2000, pp
13-21
Trends in environmental measures
for air filters
Switching to environmentally conscious
filters for business use air conditioning
is increasing in Japan, and chlorine-free,
washable or volume reduction
types are available. Such demand is particularly
strong among factories and
companies implementing environmental
management systems. Replacing metal
or glass fiber air filters for ovens with
organic fiber types or simplifying air filter
structures for clean rooms are also
very effective in improving safety, productivity
and quality. Halogen-contain-
INJ Summer 2001 53

NONWOVENS ABSTRACTS
ing material has been used to add fire
resistance, but concerns about dioxin
creation means air filters free from halogen
or chlorine are sought. Cleaning
used air filters with supersonic wave has
been highlighted as new business.
Standards must be clarified to assure the
safety and performance of cleaned filters
for reuse. (11 fig, 3 tab, 3 ref)
Author: Tomioka T
Source: Nonwovens Rev.
Issue: vol. 11, no. 4, Dec. 2000, pp 1-7
(In Japanese)
Prospect of development of medical
nonwovens products
Ease of putting on or off, permeability,
and water and alcohol repellent properties
are essential for surgical gowns.
Lint creation must be minimized to
avoid affecting micro-surgery, and fire
resistance is required where electrical or
high frequency tools are used.
Kimberly-Clark’s SMS (spunbond/meltblow/spunbond)
is excellent for gowns
and drapes, and a shift to SMS from wet
nonwovens or spunlace is underway in
the U.S. The Japanese market is 10 years
behind, but the recognition of medical
nonwovens is increasing due to its effectiveness
in preventing surgical site infection.
Developing set products of nonwoven
items or kit products including pharmaceuticals
and tools per surgery type
has become popular. They are considered
to improve efficiency in surgical
operations, but require huge investment
for manufacturing equipment and licensing
procedure. (7 fig, 5 tab, 1 ref)
Author: Yamamoto H
Source: Nonwovens Rev.
Issue: vol. 11, no. 4, Dec. 2000, pp 8-
14 (In Japanese)
Today defines the future
Details of the rise of the production of
polyester in Asia, North America, West
Europe, Africa, Middle East, South
America and East Europe; the world
supply of polyester, the general demand
for fibers in the world and dynamics of
the price changes, profit on polyester
staple fiber and pre-oriented thread in
East Europe are all outlined. China and
54 INJ Summer 2001
other Asiatic countries understand that
having an enormous volume of production
and consumers for chemical fiber
(polyester included), they cannot coexist
with the raising of their prices.
Another approach practiced unfortunately
by many enterprises in Russia and
Belarus has an especially competitive
and temporary character which is
fraught with the possibility of a return to
the days of the shuttle.
Author: Eisenstein E
Source: Text. Ind.
Issue: no. 6, 2000, pp 35-38 (In
Russian)
Cellulosic microfibers from a synthetic
matrix
Applications for microfibers are
increasing as production processes
evolve. Suitable spinning processes for
natural polymer microfibers finer than
0.5 dtex are now being developed. A
method of manufacturing cellulose
microfibers is described, which is based
on the lyocell NMMNO process. A cellulose/NMMNO
solution is mixed with
an inert fiber forming viscous polymer
solution or melt, using static mixers, and
an “island in the sea” matrix-fibril-fiber
(MFF) obtained after removal of the
polymer solvent and NMMNO.
Commercially available copolyamides
and plasticized polystyrene are suitable
matrix polymers for the limited range of
processing temperatures. Further work is
needed to control fineness and shape of
MMFs. (6 fig, 3 ref)
Author: Riedel B; Taeger E; Riediger W
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, pp 7-8
Voluminous, compressible nonwovens
with isotropic strength and elongation
characteristics
Maliknit and Kunit webs, and
Multiknit nonwovens produced by the
Malimo stitch-bonding technique are
mainly used as sub-upholstery in car seat
cover composite systems. The voluminous
stitch-bonded materials have
almost isotropic strength and low initial
elongation values, while being compressible.
Experiments are described
which assess the effects of processing
parameters such as fiber properties,
number of doubled layers of the crosslaid
web, weight per unit area of web,
lift of brush bar and stitch length. By
using cross-laid webs and applying thermal
treatment, the same tensile strength
values can be almost achieved in lengthwise
and crosswise directions, which
facilitates handling and further processing.
(6 fig, 4 tab, 3 ref)
Author: Erth H
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, pp 17-
20
Evolon - a new generation of technical
textiles
Evolon nonwovens by Freudenberg
Vliesstoffe KG, Weinheim, Germany,
are made of microfilaments spun directly
from the polymer. The continuous
manufacturing process spins, splits and
bonds the filaments by high-pressure
water jet. The resultant high tenacity
isotropic fabrics have high density and
relatively low air permeability, and can
be finished according to specific end
requirements. Titer range of the filaments
is between 0.05-0.15. Properties
of the primary material and the diverse
finishing possibilities open up wide
ranging potential applications. These
include automotive and household textiles,
shoes and clothing. The properties
and advantages for each sector are tabulated.
(4 fig, 1 tab)
Author: Schuster M
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, p. 21
Interaction between protection and
physiological parameters in firefighters'
protective clothing
The interactions between protection
and comfort parameters in heat protective
clothing, especially between heat
and mass transfer, are analysed. While
optimal heat and moisture transport are
required, so are barrier properties against
external hazards which usually result in
increased bulk of clothing. The test methods
are repeatable and reproducible, but
assess different parameters separately

NONWOVENS ABSTRACTS
using small samples, which cannot give
an overall reflection of a complete clothing
system. The categories of conditions
to which firefighters are exposed during
a fire, the influence of humidity on heat
protection, and protection against hot
steam are discussed, with reference to the
tests conducted on sample materials and
their results. (7 fig, 9 ref)
Author: Rossi R
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, pp 22,
24-25
Current trends in automotive textiles
A discussion is reported, with the
director of JH Ziegler, of Achern,
Germany, about Techtextil 2001 in
Frankfurt. The automotive industry
forms the core market for the technical
nonwovens and web/foam composites
developed as alternatives to foam for
upholstery materials. A polyester and
wool web is used instead of backing
foam under fabric for Mercedes C and
E class cars, and laminated nonwovens
have replaced wadding under leather
seats in the Audi 4. Nonwovens are
likely to continue their growth in this
sector as they can be recycled, are easily
processed, and have air and water
vapor permeability. JH Ziegler is active
in other markets, such as office furniture,
building, glass fiber reinforced
plastic and fire blockers. (Short article)
Author: Anon
Source: Tech. Text.
Issue: vol. 44, no. 1, Feb. 2001, p. 36
Geotextiles: packed with potential
The present and future use of geotextiles
in India is considered. Varying soil
types and climatic conditions present
potential applications for repair and new
constructions, and an abundance of natural
fibers could provide cost-effective
material solutions. The different types
of geotextiles and their applications are
described. Since the first Indian
Geotextiles Conference in Mumbai in
1988 the government has sponsored
various research projects, and demand
is increasing for high performance civil
engineering structures. The Super
Express Highway Scheme involves constructing
a six lane road covering 7,000
km. Other geotextile installations
include those in river beds and canals
for erosion control, railway reinforcement,
filtration and drainage, and prevention
of pavement cracks. (5 fig, 1
tab, 10 ref)
Author: Patel P C; Vasavada D A
Source: Indian Text. J.
Issue: vol. 111, no. 1, Oct. 2000, pp 35-
42
Do you know: that nylon carpets can
be depolymerised?
Feasibility tests were carried out to
investigate the potential of an environmentally
friendly method of producing
caprolactam. Pelletized nylon carpet was
treated in the presence of steam under
medium pressure, for eight runs. The
best run at 340 0 C, 6g/min steam at 1500
kPa for three hours, yielded 95% caprolactam,
with a purity of 94.4%, giving a
total output of 89.7%. A computer model
was constructed from the laboratory data
for batch and continuous flow stirred
reactors. (1ref) (Short article)
Author: Shenai V A
Source: Indian Text. J.
Issue: vol. 111, no. 1, Oct. 2000, p. 64
Material recycling of thermoplastic
FPC
The IVW GmbH, Kaiserslautern,
Germany, has used GMT scrap for
assessing the cost benefits to processors
of recycling fiber-reinforced plastics
(FRP) with a thermoplastic matrix. The
mechanical recycling process is compared
with conventional waste disposal.
Third party recycling is considered, and
in-house recycling for an existing and
new process, taking into account the
investments required. Data used to calculate
recycling costs are tabulated. The
recycling of non-contaminated production
scrap and of used parts is discussed.
(5 fig, 3 tab)
Author: Mattus V; Beresheim G; Neitzel M
Source: Kunstst. Plast Eur.
Issue: vol. 90, no. 12, Dec. 2000, pp
23-25
Latest trends of nonwovens processing
equipment
Since spunlace types appeared in
Japanese wiper market around 1990,
various features, including packaging
form, folding style or combination of
pharmaceuticals, have been added to
products, requiring more complex technology
for finishing. Controlling lint
from cut ends is essential for use in clean
rooms or high-level hygienic areas.
Kishi Seisakusho KK has developed a
clean-cut system with lint suction function.
Kishi has also succeeded in modifying
inter folder and multi folder for
paper to nonwovens use, and developing
a face mask manufacturing machine
from wiper folder. High-speed rotary
heat-sealing is carried out to make bags
of PP spunbond or thermalbond nonwovens,
but sometimes poor sealing occurs.
Kishi has developed a repetitive sealing
system for the same location to ensure
correct sealing. (14 fig)
Author: Kishi Y
Source: Nonwovens Rev.
Issue: vol. 11, no. 4, Dec. 2000, pp 15-
19 (In Japanese)
Filter removes contaminants from liquids
and gases
A patented filter material to enable
environmentally friendly disposal of
contaminants contained in industrial
exhaust water has been developed by
Chelest Corp and Chubu Chelest Co Ltd,
Osaka, Japan. The difficulties of removing
metal ions from exhaust water are
explained. The new product is an easily
disposed of fibrous chelate-forming
material which captures metal ions more
effectively than conventional chelate
resin and can be used with various fluids
which are listed. Full company contact
details are supplied. (Short article)
Author: Anon
Source: New Mater. Jpn
Issue: Mar. 2001, p. 6 — INJ
INJ Summer 2001 55

INJ DEPARTMENTS
THE WORLD OF
ASSOCIATIONS
New Technical Director for INDA
With the departure of Chuck Allen
from the position of INDA’s Technical
Director at the end of 2000, a search for
a replacement was initiated. The position
was filled this Spring with the
announcement that Cos Camilio would
be the new Technical Director.
In this assignment, “Cos” will continue
to important role that the Technical
Director has played in the operation of
INDA. This will entail direction and
management of all technical activities
within the association’s operational
team. He will be a member of INDA’s
several committees, playing a major
role with TAB (Technical Advisory
Board). He will also serve as
Association Editor of International
Nonwovens Journal, as well as represent
the association in contacts with
other trade associations worldwide, and
with various industry and governmental
groups.
Cos Camilio has a long-term association
with the nonwovens industry. He
began his career with the Chicopee
Division of Johnson & Johnson, following
graduation from Tufts
University with a B.S. degree in
Chemical Engineering. After 20 years
with Chicopee and a variety of increasingly
responsible positions, he joined
the Freudenberg group in
Massachusetts. At this subsidiary of
Carl Freudenberg in Germany, he
served in a number of positions. At one
point he was Senior Vice President-
Manufacturing, with responsibility for
Operations, Research and Engineering.
Camilio was President and CEO of
Freudenberg’s Staple Fiber Division in
Chelmsford, MA, and later at the company’s
Durham, NC Operation. At this
56 INJ Summer 2001
location he also was the Chief
Operating Officer of
Pellon/Freudenberg Nonwovens Ltd
Partnership (FNLP). In all of these
assignments, Cos had close association
with many members and operations of
the Freudenberg family, which has
plants in several countries throughout
the world, and is the world’s largest
nonwovens company.
In addition to his degree in Chemical
Engineering, Cos earned an MBA in
Business Administration from Western
New England College.
Welcome to your new assignments,
Cos, and good luck.
Journal on Textiles and Apparel
A new technical journal has been
inaugurated to serve professionals in
the area of textiles and apparel. This
journal, The Journal of Textile and
Apparel, Technology and Management
(JTATM), is an on-line publication, and
is available at www.tx.scsu.edu/jtatm.
JTATM is being coordinated by the
Department of Textile and Apparel,
Technology and Management, within
the College of Textiles at North
Carolina State University.
The goal of the publication is to present
the latest in theoretical and empirical
research in the field of textile and
apparel, technology and management to
an audience comprised of academicians,
industry executives, and consultants.
The Journal will focus on all activities in
the science, technology, design and
management aspects in the development
of products fabricated from fibers. The
contact for the new publication is Dr.
Nancy Cassill, Professor, College of
Textiles, NCSU, Raleigh, NC 27695;
919-513-4180; Fax: 919-515-3733;
Nancy_Cassill@ncsu.edu.
The forthcoming issue of JTATM will
carry the abstracts of the 2001 Spring
Meeting of the Fiber Society, which
was held at the College of Textiles at
NCSU.
— INJ
ANALYSIS AND FORECAST OF THE
NORTH AMERICAN NONWOVENS BUSINESS
An updated edition of the report, entitled “The Nonwovens Industry in North
America – 2000 Analysis,” has been prepared and is being offered for sale
by INDA. This report has been prepared from detailed industry research as well
as input from industry members. It probably represents the most complete and
authoritative report ever on the North American industry. The first of this series,
March 200 Analysis, The Nonwovens Industry in North America, was completed
and issued over a year ago.
The current report covers the following categories:
• Overview – over 2 billion pounds, 9% annual growth rate.
• Roll Goods Markets By End Use – dollars, square yards, pounds.
• Short-Life Markets.
• Long-Life Markets.
• Process Volumes.
• Review of Top 10 Roll Goods Producers.
The report was discussed in detail by Martec representatives, the marketing
organization that prepared it, in a recent seminar that allowed participants to
question and discuss the contents. Copies of the report can be purchased from
INDA, 1300 Crescent Green, Suite 135, Cary, NC 27511. 919-233-1210; Fax:
919-233-1282; www.inda.org.

INJ DEPARTMENTS
NONWOVENS
CALENDAR
July 2001
July 10-12. INDA Nonwovens
Training Course. INDA Headquarters,
Cary, NC. INDA, 1300 Crescent Green,
Suite 135, Cary, NC 27511. 919-233-
1210; www.inda.org.
July 12-18. Introduction to Textile
Testing, AATCC Technical Center,
Research Triangle Park, NC 27709.
American Association of Textile
Chemists and Colorists; 919-549-3526;
Fax: 919-549-8933.
July 19-22. Clean ‘01; The
Educational Congress for Laundering
and Drycleaning. New Orleans,
Louisiana, USA. Ann Howell, Riddle &
Associates, 1874 Piedmont Rd., Suite
360-C, Atlanta, GA 30324; 404-876-
1988; Fax: 404876-5121; ann@jriddle.com;
www.cleanshow.com
August 2001
Aug. 16-19. Bobbin World 2001,
Orange County Convention Center,
Orlando, FL, USA. Bill
Communications, P.O. Box 61278,
Dallas, TX 75261; 972-906-6800; 800-
789-2223; www.bobbin.com.
September 2001
Sept. 5-7. INTC, International
Nonwovens Technical Conference.
Renaissance Harborplace Hotel,
Baltimore, MD, USA. INDA, P.O.
Box 1288, Cary, NC 27512-1288;
Tel: 919-233-1210; Fax: 919-233-
1282 or Karen Van Duren, TAPPI;
770-209-7291.
Sept. 19-21. EDANA OUTLOOK
Conference on New Personal Care
Products, Hotel de Paris, Monte-Carlo.
Philip Preest, Marketing Director,
EDANA, 157 avenue Eugène Plasky,
Bte 4; 1030 Brussels, Belgium; Tel.:
32+2/734-9310; Fax: 32+2/733-3518;
www.edana.org.
Sept. 20-21. 9th International
Activated Carbon Conference,
Pittsburgh, PA. PACS, Coraopolis, PA;
800-367-2587; Fax: 727-457-1214.
Sept. 24-26. Shanghai International
Nonwovens Conference and Exhibition
(SINCE) and Expo Nonwovens Asia
(ENA), Hong Kong. 65+294/ 3366.
Sept. 25-27, 2001. EDANA
Nonwovens Training Course, Brussels,
Belgium. Cathy Riguelle, EDANA, 157
avenue Eugène Plasky, Bte 4, 1030
Brussels, Belgium; 011+32+2/734-
9310; Fax: +32-2/733-3518;
www.edana.org.
Sept. 27-28. International Conference
for Manufacturing of Advanced
Composites, Ireland. Lisa Bromley or
Angela Douglas; 44+20/7451-7302 or
7304; www.globalcomposites.com
Sept. 30-Oct. 4. 2001 Eastern
Analytical Symposium; Atlantic City,
NJ. Major conference on analytical and
the allied sciences. Eastern Analytical
Symposium, P.O. Box 633,
Montchanin, DE 19710; 610-485-4633;
Fax: 610-485-9467; www.eas.org
October 2001
Oct. 8-13. OTEMAS. 7th Osaka
International Textile Machinery Show.
Intex Osaka, Japan. Naad International,
+81-6-945-0004; 800/716-9338; Fax:
+81-6-945-0006. www.textileworld.com
Oct. 9-11. INDA Nonwovens
Training Course. INDA Headquarters,
Cary, NC. INDA, 1300 Crescent Green,
Suite 135, Cary, NC 27511. 919-233-
1210; www.inda.org.
Oct. 15-19. ITMA Asia 2001,
Singapore Exposition. Singapore.
ITMA Asia 2001 Organizer, 20 Kallang
Avenue, 2nd Floor, Pico Creative
Centre, Singapore 339411; Tel: 65-297-
2822; Fax: 65-296-2670/292-7577.
mpgroup@pacific.netsg; www.itmaasia2001.com
.
Oct. 16-18. EDANA Absorbent
Hygiene Products Training Course.
Brussels, Belgium. Cathy Riguelle,
EDANA, 157 avenue Eugène Plasky,
Bte 4, 1030 Brussels, Belgium;
011+32+2/734-9310; Fax: +32-2/733-
3518; www.edana.org.
Oct. 18-20. IFAI Expo 2001.
Nashville, TN, USA. For more information
contact: Jill Rutledge, IFAI, 1801
County, Roseville, MN 55113; Tel:
651/225-6981; 800/225-4324; Fax:
651/631-9334; jmrutledge@ifai.com
Oct. 21-24. American Association of
Textile Chemists and Colorists,
International Conference and
Exhibition, Palmetto Expo Center,
Greenville, SC, USA. AATCC; 919-
549-8141; www.aatcc.org
Oct. 25-Nov. 1. K2001-15th
International Trade Fair for Plastics and
Rubber. Dusseldorf, Germany. Messe
Dusseldorf. Tel: +49-211-4560-01; Fax:
+49-211-4560-669. info@messe-dusselforf.de
November 2001
Nov. 6-8. 11th Annual TANDEC
Conference. University of Tennessee,
Knoxville, TN 37996. Dr. Dong Zhang,
Conference Chairman, Textiles and
Nonwovens Development Center; 865-
974-3573; Fax: 865-974-3580. tancon@utkux.utk.edu
December 2001
December 4-6. Filtration 2001
International Conference & Exposition.
Navy Pier, Chicago, IL. INDA, P.O.
Box 1288, Cary, NC; 919-233-1210;
Fax: 919-233-1282; www.inda.org.
Dec. 4-6. EDANA Nonwovens
Training Course. Brussels, Belgium.
Cathy Riguelle, EDANA, European
Disposables & Nonwovens Association,
157 avenue Eugène Plasky, Bte 4, 1030
Brussels, Belgium; 011+32+2/734-
9310; Fax: +32-2/733-3518;
www.edana.org. — INJ
INJ Summer 2001 57

World’s Largest
Filtration
Event
DECEMBER 4-6, 2001 • NAVY PIER • CHICAGO, IL
Get the
Competitive
Edge
Exhibit!
Attend!
Discounts for the
American Filtration &
Separations Society,
American Institute of
Chemical Engineers,
Filter Manufacturers
Council, Filtration
Society of Europe/Asia,
GEO-Institute of
American Society of Civil
Engineers, INDA,
National Air Filtration
Association, and
Technical Association of
the Pulp and Paper
Industry.
• 2500 Professionals from around the
world expected to attend.
• Exhibit to increase by 35%.
• Air/Gas and Liquid Sessions.
Filtration 2000
Big Success!
• 950 Companies Represented
• 2,000 Attendees
• 250 International Attendees
• 30 Countries Represented
• 43 States Represented
• 175 Exhibitors
• 43% of Attendees were
Key-Decision Makers
• 72 % of Attendees were Non-Members
and Customers for Exhibitors
Please complete and return to Filtration 2001 or fax to 919-233-1282
Send me more information about ❏ Attending ❏ Exhibiting
Name ____________________________________________ Title ________________________________________________
Company ______________________________________________________________________________________________
Address _______________________________________________________________________________________________
City _________________________________________________
State ____________________________ Country _____________________ Zip/Postal Code ______________________
Telephone _______________________ Fax _________________________ e-mail ______________________________
Return To: Filtration 2001, INDA, P.O. Box 1288, Cary, NC 27512-1288, 919-233-1210, Ext. 0, Fax 919-233-1282