Methods for Investigation of Yarn Structure and ... - Centrum Textil

Methods
for investigation of yarn
structure and properties
Dana
Kremenakova
Technical University
of Liberec
Textile Faculty
Textile research center
Czech Textile Seminar Greece May 2005

SYSTEM OF EXPERIMENTAL
METHODS - Application
• For quality evaluation of fibers, yarns,
weaves, etc.
• For verification of theoretical models,
which describe structure and
properties of textiles
• For evaluation material and
technological parameters of textiles
• For technical design

Application
of Image Analysis
• Method selection
• Sampling and sample
preparation
• Primary processing of image information
1. Image preprocessing (image enhancement,
image restoration) elimination of signal noise, change
of brightness
2. Image analysis (image coding - compression)
detection of lines, areas, shape information,
saving of data files
• Secondary data treatment

Special
methods
• FIBERS
Longitudinal views:
identification, length, diameter (fibers
with round profile), surface faults
Cross-sections:
area, perimeter – computation of
fineness, shape factor, specific surface,
degree of cottonization of ultimate flax
fibers

Special methods
YARNS
Longitudinal views: hairiness, diameter,
fiber slope, belt fibers of rotor yarn, cover
factor of wrapped core yarn, yarn
compression between two parallel plates,
deformation in simulated binding point
Cross-sections: fiber
number, packing density,
diameter, porosity, blending
uniformity, mass (volume)
blend portion

Special methods
• FABRICS
Longitudinal views: area geometry -
cover factor, porosity, yarn diameter,
surface faults
Cross-sections: binding point geometry

Internal standards
using existing ISO system
IN 11-108-01/01 Definitions. Geometrical fiber properties.
IN 12-108-01/01 Definitions. Geometrical properties of staple yarns.
IN 21-108-01/01 Establishing of fiber geometrical properties.
IN 21-108-02/01 Establishing of bast fibers cottonization degree.
IN 22-102-01/01 Yarn diameter and hairiness.
IN 22-103-01/01 Yarn packing density. Direct method and Secant
method.
IN 22-105-01/01 Belt fibers of open-end yarn.
IN 23-107-01/01 Cover factor of fabrics.
IN 46-108-01/01 Recommended procedure for preparation of sample
cross-section. Soft and hard sections (slices).

No.
I. Structure and properties of
100% cotton yarns [1]
Yarn count [tex]/
twist [m -1 ]/
(coeff.) [m -1 ktex 2/3 ]
Technology
Fiber count [tex]/
Length[mm]/
Tenacity[cN/tex]
1 10/1189 (60) Combed ring 0,148/30/34
2 10/1232 (60) Combed experimental 0,148/30/34
3 20/889 (65) Carded ring 0,196/25/19
4 20/888 (65) Rotor 0,196/25/19
5 20/802 (65) Carded experimental 0,196/25/19
6 29,5/658 (65) Carded ring 0,183/25/20
7 29,5/681 (65) Rotor 0,183/25/20
8 29,5/652 (65) Carded experimental 0,183/25/20

Analysis of yarn cross-sections
20 tex
ring
rotor
experimental

METHODS FOR YARN PACKING DENSITY
EVALUATION
Direct method and Secant method [2], [3]
INPUT DATA
• Fiber fineness and mass density (for all
components)
• Yarn fineness and twist
• Text files of fiber gravity
centers (method Secant)
• or graphical files of fiber
contours (direct method)
• Width of annular rings

EXPERIMENTAL METHODS
FOR YARN PACKING DENSITY
EVALUATION
1. Input
SECANT METHOD
• fibers center of gravity
detection
DIRECT METHOD
• detection of real fibers
area
• correction yarn crosssection
images
(separation,
transformation to binary
form, noise removing)
• fibers center of gravity
computation

2. Computation
SECANT METHOD
• yarn axis definition
• radial analysis
• construction of equivalent
circle
• correction of non circularity
caused by yarn twist
• computation of packing
density
• correction for fiber migration
- coefficient Ks
DIRECT METHOD
• yarn axis definition
• radial analysis
• computation of packing
density

3. Output
SECANT METHOD
DIRECT METHOD
for single yarn and blended yarn
radial packing density
effective yarn diameter
effective yarn packing density
fiber number in yarn cross-section
coefficients of fiber arrangement
only for blended yarn
mass blend portion as a function of distance from
yarn center

Radial packing density →
effective yarn diameter – radial packing density 0,15
effective packing density – fiber cross-sec. area
/whole yarn cross-sec. Area (circle with diameter d )
0,4
0,35
d = 4T
πµρ
packing density [1]
0,3
0,25
0,2
0,15
0,1
0,05
0
0,01 0,04 0,07 0,1 0,13 0,16 0,19 0,22 0,25 0,28
d/2
yarn radius [mm]

NUMBER OF FIBRES IN YARN CROSS-
SECTION
n=k n * yarn fineness/fiber fineness
ring
rotor
experimental
[tex]

RADIAL PACKING DENSITY
packing density [-]
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
1. ring 10 tex
2. experimental 10 tex
3. ring 20 tex
4. rotor 20 tex
5. experimental 20 tex
6. ring 29,5 tex
7. rotor 29,5 tex
8. experimental 29,5
0 0,04 0,08 0,12 0,16 0,2 0,24 0,28
yarn radius [mm]

Radial
packing density
packing density [1]
0,8
0,6
0,4
0,2
0
65%PET/35% bavlna
0,01 0,03 0,05 0,07 0,09 0,11 0,13 0,15 0,17 0,19
ring 25 tex,
640/m
rotor
25 tex,940/m
yarn radius [mm]
0,6
the same twist
0,6
0,5
higher twist
of rotor yarn
packing density [ ]
0,5
0,4
0,3
0,2
0,1
20 tex
radiální zaplnění [ ]
0,4
0,3
0,2
0,1
0
detail
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2 0,22 0,24 0,26
poloměr příze [mm]
0
0,00 0,04 0,08 0,12 0,16 0,20 0,24 0,28
ring experimental rotor
yarn radius [mm]

EFFECTIVE PACKING DENSITY
EFFECTIVE YARN DIAMETER
ring
rotor
experimental
[mm]
d = 4T
πµρ
[tex]

YARN HAIRINESS
10 tex
29,5 tex
20 tex

Definition
Hairiness - characterizes the amount of free
fibers (fiber loops) protrudes from the
compact yarn body towards the outer yarn
surface (fabric, knittings, etc.)
Evaluation criteria –
number of free fibers
(length and area units)

Measurement
of yarn hairiness
1. Zellweger hairiness meter USTER-
TESTER 4-scanning of light intensity of
illuminated fibers, hairiness index H total
length of all fibers protruding from the yarn
body, which are measured on the 1 cm yarn
length
2. Zweigle hairiness tester – photo-electric
sensors, number of fibers protruding from
the yarn body, 12 classes

3. YARN HAIRINESS
and YARN DIAMETER
[4]
Line of
pixels
• Light rays passing trough
yarn
• Recognition between
yarn body and hairiness
area
• Model of „dense” and
„thin” hairiness
• Experimental curve
related to frequency of
occurring black pixels as
a function of distance
from yarn axis

Hairiness function
Yarn diameter - 50% of hairiness function
Constant value – integral under hairiness
function in interval (D/2;3*D)
1,2 3,4,5 6,7,8
Ring/experimental/rotor
R1

Hairiness USTER
Yarn hairiness
Hairiness TUL
ring
rotor
experimental
[tex]

Yarn unevenness
Irregularity index
[%]
ring
rotor
experimental
CVlim = 100
n e
I
=
CV
Uster
CV lim
[tex]
Martindale equation

[%]
Yarn tenacity
elongation
fiber utilization fact.
[N/tex]
ring
rotor
experimental
[tex]

Conclusion 1:
Influence of fineness and technology
100% cotton ring yarns, experimental and
rotor yarns
neps +200% 350
thick +50% 300
250
thin -40% 200
150
uneveness index 100
50
0
CV Uster
yarn elongation
FUF
yarn tenacity
hairiness Uster
fiber fineness
fiber length
fiber tenacity
yarn fineness
twist coefficient
yarn twist
fiber number
yarn diameter
packing density
hairiness TUL
10 tex ring
10 tex experimental
20 tex ring
20 tex experimental
20 tex rotor
29,5 tex ring
29,5 tex experimental
29,5 tex rotor

No.
II. 100% Cotton Ring
and Compact Yarns
[5]
Yarn count [tex]/
twist [m -1 ]/
(coeff.) [m -1 ktex 2/3 ]
Technology
Fiber count [tex]/
Length[mm]/
Tenacity[cN/tex]
1 7,4/1307 (50) ring 0,146/29/40
2 7,4 /1262 (50) compact 0,148/29/31
3 11,8 /1066 (55) ring 0,196/29/39
4 20/1059 (55) compact 0,196/29/34
5 20 /944(70) ring 0,183/29/22
6 29,5/977 (70) compact 0,183/29/23

RADIAL PACKING DENSITY
compact and ring yarn7,4 tex, 100% cotton,
twist ring 1307/m, compact 1262/m
Radial packing density [-]
0,6
0,5
0,4
0,3
0,2
0,1
0
Compact FUF 65% H 2,8 Ring FUF 38%, H4,1
0 0,02 0,04 0,06 0,08 0,1 0,12
Yarn radius [mm]

compact
ring
PACKING
DENSITY
RADIAL
AND
EFFECTIVE
Radial pack ing dens ity [-
]
0,6
0,5
0,4
0,3
0,2
0,1
0
0 0,03 0,06 0,09 0,12 0,15 0,18
Yarn radius [mm]
0,48
20 tex
Radial pack ing dens ity [-]
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
compact
ring
11,8 tex
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14
Yarn radius [mm]
packing density [-]
0,47
0,46
0,45
0,44
0,43
0,42
C
C
5 10 15 20
yarn fineness [tex]
C

HAIRINESS
yarn diameter [-]
0,19
0,18
0,17
0,16
0,15
0,14
0,13
0,12
0,11
0,10
0,09
C
C
5 10 15 20
yarn fineness [tex]
C
R1

0,024
0,022
0,020
HAIRINESS
TUL
HAIRINESS
USTER
hairiness TUL
0,018
0,016
0,014
0,012
0,010
0,008
3 3 4 4 5 5 6
hairiness Uster
0,024
0,022
hairiness TUL [-]
0,020
0,018
0,016
0,014
0,012
0,010
0,008
C
C
5 C 10 15 20
hairiness Uster [-]
5,50
5,00
4,50
4,00
3,50
3,00
2,50
5 10 15 20
yarn fineness [tex]
yarn fineness [tex]

tenacity [cN/tex]
0,24
0,23
0,22
0,21
0,20
0,19
0,18
0,17
0,16
0,15
TENACITY
ELONGATION
FIBER
UTILITY
FACTOR
C
C
5 10 15 20
elongation [%]
yarn fineness [tex]
6,00
5,50
5,00
4,50
4,00
3,50
C
5 0,75 10 C 15 20
0,70 C
yarn fineness [tex]
0,65
C
FUF [%]
0,80
0,60
0,55
0,50
0,45
0,40
0,35
0,30
C
C
5 10 15 20
yarn fineness [tex]
C

Conclusion 2:
Influence of fineness and technology
100% cotton ring yarns and compact yarns
fiber fineness
neps +200% 250 fiber length
thick +50% 200 fiber tenacity
thin -40% 150
100
fiber elongation
uneveness index
CV Uster
50
0
yarn fineness
yarn twist
yarn elongation
FUF
yarn tenacity
hairiness Uster
fiber number
yarn diameter
packing density
hairiness TUL
7,4 tex ring
7,4 tex compact
11,8 tex ring
11,8 tex compact
20 tex ring
20 tex compact

III. Structure and properties
of blended yarns [6]
50% cotton / 50% flax yarns
No.
Yarn count [tex]/
twist [m -1 ]/
(coeff.) [m -1 ktex 2/3 ]
Technology
1 24/968(81) 45%cotton/55%flax
ring
2 24 /981 (83) 50%cotton/50%flax
experimental
3 24/1261 (105) 50%cotton/50%flax
rotor
Fiber count [tex]/
Length[mm]/
Tenacity[cN/tex]
Co 0,176/22/32
Flax 0,336/23/40
Co 0,173/32/34
Flax 0,376/29/50
Co 0,173/32/34
Flax 0,376/29/50

Flax fiber separation [7]
Parallel fiber cross–sections
before cottonization (left) after cottonization (right),
reflected light, electron microscope Aquasem

e lative fre que ncy [-]
relative frequency [-]
Relative frequency of fibers bundles occurrence
Histogram of fiber fineness
Correlation between number of fibers in bundle and
bundle fineness [7]
0,6
0,4
0,2
0
0,3
0,25
0,2
0,15
0,1
0,05
0
1 2 3 4 5 6 7 8 9 10
number of fibers in bundle [-]
0,1 0,3 0,5 0,7 0,9 1,1 1,3 1,5
fiber fineness [tex]
bundle fineness [tex]
12
10
8
6
4
2
0
experiment
regression
0 10 20 30
number of fibers in bundle [-]

Distribution function of fibers bundles
1
distribution function
0,9
0,8
0,7
0,6
0 5 10 15 20 25 30 35 40 45
number of fiber bundle
1. original tow
3.enzymatic tr.
3F. mechanical tr.
F1 separation
R10 =100(1-F10) aggregation

Typical yarn cross-section of
50% cotton/50% cottonized flax yarn
packing density [-]
1
0,9
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
direct
direct
Secant
Secant
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2
yarn radius [mm]

RADIAL PACKING DENSITY
yarns 24 tex, 50%cotton/50% cot. flax, twist experimental
981/m, ring 968/m, rotor 1261/m
0,7
experimental FUF 28% H7,5
ring FUF 34% H8,1
rotor FUF 21% H8,0
0,6
packing density [-]
0,5
0,4
0,3
0,2
0,1
0
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2
yarn radius [mm]

50%cotton/50%flax
ring, rotor, experimental
yarn 24 tex
co exp fl exp co ring
fl ring co rotor fl rotor
0,8
packing density [-]
0,7
0,6
0,5
0,4
0,3
0,2
0,1
hmotnostní podíl [-
0,7
0,6
experimental ring 0,5 rotor
0,4
0,3
0,2
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14
polomě r [mm]
0
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2
dameter [mm]

50%cotton/50%flax
ring, rotor, experimental
yarn 24 tex
100
experimental ring rotor
funkce chlupatosti [%]
80
60
40
20
0
0,00 0,05 0,10 0,15 0,19 0,24 0,29 0,34
poloměr příze [mm]

Properties of cotton-flax yarn
ring experimental rotor
Mass ratio Co/flax 35/65 40/60 46/54
Eff. Diameter [mm] 0,19 0,17 0,20
Eff. packing d. [mm] 0,40 0,42 0,34
Hairiness TUL/Uster 0.022/7,84 0,023/7,36 0,023/7,89
Tenacity [cN/tex] 0,13 0,11 0,08
Elongation [%] 4,19 3,07 3,14
CV [%] 24,35 29,23 23,12
Thin -40% [km-1] 3088 6903 3813
Thick +50% [km-1] 1868 3375 1875
Neps +200% [km-1] 643 2335 2350

BLENDING QUALITY
mixing homogeneity for natural and synthetic
fibers or separation of components for core
yarns, wrapped yarns
• Arrangement of fibers in the crosssection
– radial homogeneity
• Variation of mixing degree or
composition between cross-section
– axial homogeneity
• Variation of fiber number between
cross-sections – mass unevenness

Testing of fiber bundles presence
• Yarn cross-section is divided to matrix
of cells - I.B.I. (index of blend
irregularity)
• Creation of sequences of nearest
neighbors of the specified fiber – fiber
nearest to yarn center, exhaustive
selection of all fibers in yarn crosssection

I.B.I. Index of blend irregularity
Local and global estimates of probabilities , χ2 test
m-number of cells, N i
- fiber number in i-th cell; α 1
=N 1
/N, etc.
m
2 m
2
( N −α
N ) ( N −α
N )
χ =
∑
1i
α N
i=
1 1
N 1i
+ N 2i
= N i
; α 1
+α 2
=1
2
χ =
m
∑
α
2
1
1
+
∑
2i
α
i=
1 2
2
2 m
( N −α
N ) + α ( N −α
N ) ( N −α
N )
1i
i=
1 1 2
I.B.I.
=
1
α α
2
N
2i
2
=
m
1 N −
∑
1i
1
m
i=
1
α1α
2
N
2
∑
1i
α α N
i=
1 1 2
( α )
N
N
2
1
2

Cross-sec no. 2 good, no. 3 bad
Good
Bad

1,35
I.B.I.
1,25
1,15
1,05
0,95
0,85
rectangular
rectangular
radial
radial
pie segment
pie segment
0,75
0 1 2 3 4
“Good” arr.
cross-section
n.2
“Bad” arr.
cross-section
n.3
Ring spun
yarn
24 tex
Exper. yarn
24 tex
Open-end
yarn
24 tex
I.B.I.
rectangular
matrix [-]
0,58 1,93
1,02
(0,86;1,19)
0,98
(0,88;1,09)
1,08
(0,91;1,26)
I.B.I. radial
segments [-] 0,42 2,56
1,04
(0,80;1,28)
0,93
(0,79;1,06)
1,05
(0,85;1,26)
I.B.I. annular
segments[-] 0,96 1,74
1,25
(1,13;1,36)
0,98
(0,83;1,13)
1,23
(1,10;1,35)
I.B.I.
Between
cross-sec.[-]
- - 1,55 1,92 1,44

Experimental relative frequencies of
occurrence of fibrous bundles
1.
2.
3.
4.
5.
6.
.
.
.
1. 2. 3.
Yarn n. 2 50PET/50cotton 35 tex
H
R exp
R teor

Distribution of total number sequences
• Configuration – fully specified arrangement of fibers in the
cross-section to sequence according to specified criterion
• Sequence – set of fibers of one selected component
• Sequence length – number of fibers in tis set
• Total number of sequences – for individual components
is valid ⏐ S 1
-S 2
⏐ = 1or S 1
= S 2
• Limit configuration – limit aggregation (fiber of each
component are creating one sequence only ), limit
segregation (fiber of both components are regularly
alternated )

Distribution of total number sequences
4,5
4
A
B
A B C D E
3,5
3
2,5
2
D
C
C C A C C
D A D A D
B E E E B
1,5
1
0,5
0
0 1 2 3 4 5
E
E D B B A
1 1 1 1 2 S1
1 2 1 2 2 S2
2 3 2 3 4 S

Ising-Stevens distribution
⎛ N
P( ∑ = S ) 1 1
= ⎜
⎝ S
1
1
− 1⎞
⎛
⎟⎜
− 1⎠⎝
N
N
2
− 1
+ 1−
S
⎞
⎟
⎠
⎛
⎜
⎝
N
N
2 1 1
⎞
⎟
⎠
• Mean value E(S) and variance D(S) of total number sequences S
( ) ES
= +
NN
1 2 1 2
( ) ( )
2
DS = 2N N 2NN − N N ( N−1)
N
1 2 1 2
• For a large value of N, the distribution of total number of sequences
S can be approximated by normal one having parameters E(S), D(S).
Total number of sequences can be then transformed to standardized
random variable Z with normal distribution N(0,1).
Z
=
S
( )
− E S ±05 ,
( )
DS

Z values
Distribution of total
number sequences
Ring –4,67
Z
Experimental -7,01
Cross - sec.n.
Z
Rotor –0,57
Cross - sec.n.
Z
Z

Conclusion III
50%cotton/50%flax
ring, rotor, experimental
yarn 24 tex
cotton
flax
Fiber
properties
elongation co/flax 6/4%
length co/flax 30/28mm
300
200
100
fineness co/flax
0 +
0,17/0,37tex
tenacity co/flax
0,34/0,49N/tex
+ Pressley
0,39N/tex

Conclusion III
50%cotton/50%flax
ring, rotor, experimental yarn 24 tex
neps +200%
thick places +50%
thin places -40%
uneveness index
fineness
300
250
200
150
100
50
0
twist
ring
experimental
rotor
fiber number
diameter
packing density
CV Uster
hairiness TUL
elongation
fiber utility factor
hairiness Uster
tenacity

References
Thank you
for your
attention
[1] Křemenáková, D., Militký, J.: Influence of production technology on the cotton yarn
properties. Beltwide Cotton Utilization Conference, San Antonio, USA, January 2004.
[2] Neckář, B.: Yarns,. creation, structure, properties. SNTL Praha 1990. in Czech.
[3] Křemenáková, D.: IN 22-103-01/01 Yarn packing density. Direct method and Secant
method.Textile research Center Textile. Technical university of Liberec 2002.
[4] Neckář, B., Voborová, J.: A new Approach for Determination of Yarn hairiness. 3 d
Autex conference, Necessary Condition for Development of Civilization, June 2003
Gdansk, Poland.
[5] Nováčková, J.,Křemenáková, D.: Structural analysis of fine coton yarns. 10th
International conference Strutex 2003. Structure and structural mechanics of textiles.
Technical University of Liberec, CZ.
[6] Křemenáková, D., Ibrahim, S., Krupincová, G.: Internal Structure of Blended Flax
Yarns, International Conference Flax and Allowed Fiber Plants for Human Welfare,
December 2003, NRC Cairo, Egypt.
[7] Křemenáková, D.,Militký, J., Antonov, V.: Cottonization degree of pretreated flax
fibers. Vlákna a textil 10 (2), 82-85, 2003.