Apparel and Knitwear
Physical and Mechanical Properties of
Cotton/Spandex Fabrics
by Mona M.A. Haji, Textiles and Clothing Department , College of Arts d Interior Design for Girls, Umm Alqura
University, Makkah, Saudi Arabia
Abstract
Today, spandex is produced in US,
Europe, Asia, and Middle East. The
fabrics containing spandex is forecast
to grow in the coming years. In this
study, the physical and mechanical
properties of cotton/spandex single
jersey fabrics are investigated and the
results were compared with fabric
knitted from cotton alone and the
effect of loop length on the fabric
properties were also studied . The
statistical analysis proved that the
dimensional stability and air
permeability is adversely affected by
the percentage of spandex, whereas
bursting strength crease recovery and
pilling resistance rating have been
improved. The loop length had a
significant effect on fabric weight,
bursting strength dimensional change,
crease recovery , air permeability and
pilling resistance rating.
1. Introduction
Spandex is elastomeric fibers. It can
be stretched repeatedly to at least twice
Figure (1) The arrangement of polymer and hydrogen bonds in a relaxed and
extended spandex fiber.
their original length at room temperature;
when the extending force is removed,
they immediately return with force to
their approximate original length.
Spandex is a generic term, like polyamide
or polyester. It defines a man-made fiber
in which the fiber-forming substance is a
synthetic chain of polymer containing at
least 85% segmented polyurethane(1). It
is white or transparent in its natural state
and it can be dyed. The polymers in
spandex fibers contain soft and hard
segments (Figure 1). The soft segments
Table I : Specifications of samples
Blending
Ratio
96%
Cotton:
4% Lycra
92%
Cotton:
8% Lycra
Single Jersey
100%
Cotton:
0% Lycra
Structure
52
Loop
length
mm
Fabric
weight /
m2
Number of
Wales/cm
Number of
courses/cm
3.35
135
16
14
3
150
16
17
2.7
165
16
20
3.35
190
23
18
3
210
24
21
2.7
230
25
24
3.35
300
30
23
3
325
31
26
2.7
350
32
29
extend and retract under a pulling force;
hydrogen bonds form between the hard
segments of adjacent polymers (2).
Spandex is always blended with other
natural and synthetic fibers such as
cotton, wool, silk, and linen. Different
types of spandex material exist on the
markets with different counts, this impose
engineering the use of every type at
different spun materials and fabric
construction. The percentage of spandex
used in the knitting industry depends on
the fabric stretch required and fabric
properties (3).
Since the elasticity of these types
varies from 60% to 300%, this is
reflected on the final characteristics of
knitted fabrics. When applying the bare
type, we can introduce Spandex on
every feeder, which is known as full
plaiting. Different percentage of feeders
can contain spandex material, in case of
50% it is known as half plaiting. There
are many different counts and types of
spandex on the market (4).
"Lycra" is the trade name that DuPont
uses for their particular formula of
spandex that they sell to the textile
industry. The type of fabric and it’s end
use determine the amount and type of
Lycra required to ensure optimum
performance and aesthetics. Lycra can be
stretched four to seven times its initial
length, yet springs back to it’s original
length once tension is released (5).
Apparel and Knitwear
2. Function and features
The use of Spandex in fabrics offers
better fit on the body like a second skin
and have good shape retention without
any deformation throughout the life of
the garment especially in knitted
fabrics(6). In addition, the low moisture
absorption and resistance to normal
apparel exposure to sunlight and to
common chemicals are other features of
spandex (7).
Comfortable fit in woven fabrics,
freedom of movement, shape retention, excellent drape ability and
crease recovery.
Outstanding shape retention in
knitwear(8).
Used as a substrate for natural / synthetic leather or shoe uppers, Lycra
provides 4-5% stretch in shoes to
give maximum comfort to the
wearer(9).
Consistent quality effecting high yield
in knitting.
Almost 100% recovery in the garments.
Good resistance to chemicals(10).
3. Experimental work
3.1 Materials and sample specifications
The samples were knitted on a
Convert weft knitted machine with 66
feeders (24 gauge, 22" diameter, 1632
total needle count, with a positive yarn
feeding system) Marchizio circular
knitting machine. Ne 30/1 ring spun
cotton yarn and 44 dtex spandex were
used in the research .
Determination of air permeability:
Fabric drape was measured by using
Elester L 130apparatus according to (B.S2925:1958)(16).
4. Results and discussions
3.2 Laboratory Testing
Fabric weight
Determination of fabric weight: This
test was carried out by using Mettler H
30 apparatus according to the American
Standard specifications of (ASTM-D
3776-79) (11).
Determination of wale & course
density: This test were determined at ten
different places on every sample
calculated with a magnifying glass, and
the average values were calculated.
Determination of crease
recovery:Crease recovery was measured
by using Wrinkle recovery tester
according to ( ASTM D-1295-67) (12).
Determination of pill rating: This test
was carried out by using, Martindale
Tester, according to (ASTM D4970 D
4960) (13).
Determination of dimensional
stability: This test was carried out
according to (B.S 3424: 1974)(14).
Determination of bursting strength:
This test was carried out by using,
Bursting Tester for clothing, according to
(ASTM D3787-89) (15).
It was obvious from figure (2) that.,
the loop length has a significant effect
on the fabric weight for all fabrics, as the
loop length increases, the fabric weights
were decreased, this means that the
higher the loop length, the lower the
fabric weight.
The increase in loop length from 2.7
to 3.35 mm leads to a decrease in fabric
fabric weight up to 23%, 21% and 17%
for 0% lycra, 4%lycra and 8% lycra,
respectively for all samples. The
significant effect of loop length on fabric
weight for all tested fabrics can be
attributed to the decrease in the loop
length help to increase in stitch density
which lead to increase to fabric weight.
The statistical analysis also showed
that, the there is direct relationship
between lycra ratio and fabric weight as
the amount of lycra increase the fabric
weight increase, because the greater the
amount of lycra, the tighter the fabric
weight. By applying the ANOVA
technique we found that there is a
significant effect of both lycra ratio and
loop length on fabric weight P value
(0,.002) respectively .
Wale density
Figure (2) Relationship between loop length
and their fabric weight at different Lycra
ratio.
Figure (3) Relationship between loop length
and their number of wales/cm at different
lycra ratio.
Figure (4) Relationship between loop
length and their number of courses
/cm at different lycra ratio.
Figure (5) Relationship between loop
length and their crease recovery at different lycra ratio.
Figure (3) illustrates the relationship
between the amount of lycra and the
wale density for different loop length .
It is shown that, the amount of lycra is
significant effect on the wale density for
all tested fabrics. The greater the amount
of Lycra, the higher the wale density is.
The increase in the amount of Lycra
from 0% to 8% leads to an increase in
wale density up to 100%. The loop
length has an insignificant effect on the
wale density. This can be due to the fact
that the wale per cm depends in the first
place on the machine gauge, while after
wet relaxation this depends upon the
fabric construction as all the other
properties.
By applying the ANOVA technique It
was found that the lycra ratio had the
most significant influence on wale density
P value (0)
53
Apparel and Knitwear
rating for the tested samples produced
from single Jersey at three different loop
length. It is shown that, amount of lycra
has a significant effect on the pill rating
for all tested fabrics as amount of lycra
increase, the pill rating increase, this
means that the pill formation decrease as
amount of lycra increase, because the
greater the amount of lycra , the tighter
the fabric.
Figure (6) Relationship between loop
length and their pilling resistance rating
at different lycra ratio.
Figure (8) Relationship between loop
length and their dimensional stability
widthwise at different lycra ratio.
Figure (7) Relationship between loop
length and their dimensional stability
lengthwise at different lycra ratio.
Figure (9) Relationship between loop
length and their bursting strength at
different lycra ratio.
Course density
Figure (4), illustrate the relationship
between the amount of lycra and the
course density at three different loop
length. It is shown that, the amount of
lycra is significant effect on the course
density for all tested fabrics.
The greater the amount of lycra, the
higher the course density is. The increase
in the amount of lycra from 0% to 8%
leads to an increase in wale density up to
60% for all samples, because the greater
the amount of lycra, the tighter the
fabric. The statistical analysis also showed
that, the there is inverse relationship
between loop length and course density
as the loop length increase the course
density decrease. This could be attributed
to that the less the loop length the less
spaces between courses leading to the
inability of the fabric to have greater
number of courses. By applying the
ANOVA technique we found that there is
a significant effect of both lycra ratio and
loop length on course density P value
(0,.002) respectively.
Crease recovery angle
Figure (5) show the relationship
between the amount of lycra and the
crease recovery at three levels of loop
54
length. It is shown that, for all tested
samples the amount of lycra has a
significant effect on the crease recovery
angle. The higher the amount of lycra,
the higher the crease recovery angle is.
The increase in the amount of lycra from
0% to 8% leads to an increase in crease
recovery up to 25%. This means that, as
the amount of lycra increases, the crease
resistance also increases, because the
greater the amount of lycra more the
elasticity of the fabric.
The statistical analysis also showed
that, the there is inverse relationship
between loop length and crease
recovery angle as the loop length
increase the crease resistance decrease.
The significant effect of the loop length
on the crease recovery can be attributed
to the less loop length associated with
increasing the fabric weight which leads
to resist the crease deformation.
By applying the ANOVA technique
we found that there is a significant effect
of both lycra ratio and loop length on
crease recovery angle P value (0,.001)
respectively.
Pilling resistance rating
Figure (6) illustrate the relationship
between the amount of lycra and the pill
It is obvious that, loop length has a
significant effect on the pill rating for all
tested fabrics, as the higher in loop
length, the lower the pill rating is this
means that the pill formation decrease as
loop length decrease. The significant
effect of the loop length on the pill rating
can be attributed to that the, decreasing
in loop length helps to reduce pilling by
tightening up and compactness the of
construction and making fiber migration
more difficult. By applying the ANOVA
technique It was found that the lycra
ratio had the most significant influence
on wale density P value (0).
Dimensional stability in the lengthwise
direction
Figure (7) illustrate the relationship
between the amount of lycra and
dimensional stability in the lengthwise
direction at three different loop length. It
is shown that, the amount of lycra has a
significant effect on the dimensional
stability in the lengthwise direction for all
samples, as the higher the amount of
lycra, the higher the dimensional change
is, (inverse relationship).
The statistical analysis also showed
that, the there is inverse relationship
between loop length and dimensional
stability in the lengthwise direction as the
loop length increase the dimensional
change decrease. The significant effect of
the loop length on the dimensional
change. By applying the ANOVA
technique we found that there is a
significant effect of both lycra ratio and
loop length on dimensional stability in
the lengthwise direction P value (0,.001)
respectively.
Dimensional stability in the crosswise
direction
Figure (8) illustrate the relationship
between the amount of lycra and
dimensional stability in the crosswise
direction at three different loop length. It
is shown that, the amount of lycra has a
significant effect on the dimensional
Apparel and Knitwear
stability in the crosswise direction for all
samples, as the higher the amount of
lycra, the higher the dimensional change
is, (inverse relationship).
The statistical analysis also showed
that, the there is inverse relationship
between loop length and dimensional
stability in the crosswise direction as the
loop length increase the dimensional
change decrease. The significant effect of
the loop length on the dimensional
change. By applying the ANOVA
technique It was found that the lycra
ratio had the most significant influence
on dimensional stability in the crosswise
direction P value (0.006).
Bursting strength
Figure (9) illustrate the relationship
between the lycra ratio and the bursting
strength at three different loop length. It
is shown that, the amount of lycra is
significant effect on the bursting strength
for all tested fabrics, as amount of lycra
increase, the bursting strength increase,
because the greater the amount of lycra,
the tighter the fabric.
The statistical analysis also showed
that, the there is inverse relationship
between loop length and bursting
strength as the loop length increase the
bursting strength decrease. The
significant effect of the loop length on
the bursting strength can be attributed
to the less loop length associated with
increasing the fabric weight which leads
to higher bursting strength. By applying
the ANOVA technique we found that
there is a significant effect of both lycra
ratio and loop length on bursting
strength P value (0,.001) respectively .
length. It is clear, for all tested samples
the amount of lycra has a significant
effect on the air permeability, as the
amount of lycra increases, the air
permeability decreases. The reduction in
the fabric air permeability with increasing
the amount of lycra can be attributed to
the higher bulk, compactness, and the
cloth thickness accompanying with a
higher amount of lycra which offer
resistance to the air permeability.
It is obvious that, loop length has a
significant effect on the air permeability
for all tested fabrics, as the greater in
loop length, higher the air permeability.
The significant effect of the loop length
on the air permeability can be attributed
to that less loop length, less spaces
between courses which offer resistance to
the air permeability. By applying the
ANOVA technique we found that there is
a significant effect of both lycra ratio and
loop length on air permeability P value
(0 ,0) respectively .
5. Conclusion
The following result are given as
under:
Air permeability:
Figures (10) illustrate the relationship
between the lycra ratio and air
permeability, at three levels of loop
All the parameters under study were
significantly affected by the amount
of spandex in the fabric and the loop
length.
It was found that, bursting strength,
fabric weight, crease recovery and
pilling resistance rating have been
improved significantly by increasing
in lycra ratio, but fabric air permeability and dimensional stability were
decreased .
Loop length had a significant effect
on the air permeability, bursting
strength, dimensional change, crease
recovery angle and fabric weight.
Pilling resistance rating is significantly
affected by loop length and percentage of spandex. It was found that the
loop length had the most significant
influence on pilling resistance rating.
References
Figure (10) Relationship between
loop length and their air permeability
at different lycra ratio.
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