Indian Journal of Fibre & Textile Research
Vol. 34, December 2009, pp. 338-344
Tensile characteristics of yarns in wet condition
A Dasa, S M Ishtiaque, S Singh & H C Meena
Department of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India
Received 22 December 2008; accepted 25 February 2009
This paper reports the tensile characteristics of cotton, polyester, viscose and polyester/viscose (P/V) ring and rotor
yarns of different linear densities and blend proportions in dry and wet conditions. An experimental set-up has been
fabricated, which can be attached with the tensile tester to study the tensile characteristics of yarns under water. The tenacity
of yarns is found to be higher in wet condition as compared to that in dry condition for all the yarns, except the viscose yarns
where tenacity drops in wet condition. The increase in tenacity in case of cotton is much higher than that in case of polyester
and P/V blended yarns. In case of polyester and cotton, the breaking elongation of yarns increases while in viscose and
viscose-rich P/V blended yarns, the breaking elongation decreases in wet condition. In viscose and viscose-rich P/V blended
ring-spun yarns, the increase in initial modulus is found to be very high, whereas in the case of polyester and cotton, there is
moderate increase in initial modulus of yarns in wet condition. In case of cotton ring-spun yarns, there is very high level of
increase in work of rupture in wet condition. Yarn fineness significantly affects the tensile characteristics.
Keywords: Breaking elongation, Cotton, Initial modulus, Polyester, Ring yarn, Rotor yarn, Tenacity, Viscose, Work of rupture
1 Introduction
There are many application areas where textile
materials are used under water, e.g. swimming or any
other under water activities. It will therefore be
beneficial to know the tensile characteristics of yarns
under water. Yarn properties, such as dimensions,
tensile strength, elasticity recovery, elongation,
modulus, rigidity, electrical resistance, and energy at
break point, are affected by the amount of water
absorbed. In the case of polyester, although the fibre
is less hygroscopic, polyester yarns or fabrics absorb
water by wicking action. Similarly, in case of yarns or
fabrics made of hydrophilic fibres or blends, the
absorption behaviour is entirely different.
There are large numbers of publications available
on the effect of various parameters on tensile
characteristics of yarn. But, almost all the studies
were carried out with normal dry yarn. Midgely and
Pierce1 first suggested the effect of rate of loading on
the tensile properties of spun yarn. Balasubramanian
and Salhotra2 and Kaushik et al.3 investigated the
influence of rate of loading on the tensile behavior of
rotor-spun yarns in dry conditions. Serwatka et al.4
gave a new approach for modeling the stress-strain
curve of linear textile products in dry conditions.
They explained the stress-strain curve of yarn in three
_____________
a
To whom all the correspondence should be addressed.
E-mail: [email protected]
zones. Robert et al.5 studied resiliency and modulus of
viscose rayon as a function of swelling and
temperature in wet condition. Bryant and Walter6
measured the tensile properties of yarn, immersed in
water, as a function of temperature. Paul et al.7
presented preliminary result of the deep star polymer
taut leg mooring project. Preston and Nimkar8 studied
the adhesion force between fibres in the yarn. They
observed that the capillary water, present in the spaces
between fibres, attracted to one another by the
hydrostatic tension in water. The present work is
undertaken to study the tensile characteristics of
different types of yarns in wet condition. The tensile
characteristics of yarns under water is expected to be
affected by fibre type and blend proportion and also
by the yarn structure. Hence, a detailed study has been
reported on the effect of blend proportion and yarn
count on tensile characteristics of ring and rotor yarns
in dry and wet (under water) conditions.
2 Materials and Methods
2.1 Materials
Polyester,
viscose
rayon,
cotton
and
polyester/viscose (P/V) blend were used for the study.
The specifications of cotton fibres were: ring-spun
yarns–2.5%
span
length
30mm,
fineness
4.2 micronaire; and rotor-spun yarns–2.5% span
length 25 mm, fineness 4.5 micronaire. The lengths
and deniers of polyester and viscose staple fibres were
DAS et al.: TENSILE CHARACTERISTICS OF YARNS IN WET CONDITION
44 mm×1.4 den and 44 mm × 1.5 den respectively.
The tensile tests of these staple fibres were carried out
in dry and wet (under water) conditions and the
results are given in Table 1. Two types of yarn
structures were used, i.e. ring-spun and rotor-spun
yarns. Ring-spun yarns were produced from different
blend proportions of polyester and viscose
(100% polyester, 65/35 P/V, 50/50 P/V and 100%
viscose) and cotton of different yarn counts (10s Ne,
20s Ne, 30s Ne and 40s Ne). Rotor-spun yarns of
different counts (7s Ne, 8s Ne, 10s Ne and 12s Ne)
were produced from only cotton.
2.2 Methods
2.2.1 Preparation of Yarn Samples
The cotton fibre was processed through blow room
and card. The carded sliver was then fed to the two
passage of draw frame to produce a sliver of linear
density 4.54 ktex. The same drawn sliver was then
processed in roving frame to produce the rovings of
required linear densities. Total twenty different types
of ring-spun yarns and four rotor-spun yarns were
studied.
2.2.2
Evaluation of
Under Water
Tensile
Characteristics
of
Yarns
An experimental set-up was fabricated to study the
tensile characteristics of yarns under water. The setup was attached with the Instron tensile tester (Fig. 1).
The tensile tests of yarns, both in conditioned yarn
(referred as dry test) and under water (wet condition),
were carried out using similar test conditions to
eliminate the possibilities of any errors introduced
during the test. The transparent water tray was filled
up with water until the yarn specimen was fully
dipped in water. The yarn specimen was placed in
between a fixed jaw and a movable jaw. The movable
jaw moves with the help of movable jaw of Instron
tensile tester through a very strong non-extensible
(extension at lower level of load was almost zero)
Kevlar string. The Instron tensile tester was then
started and the load-elongation behaviour of the yarns
under water was recorded. In this experiment, 10 kg
load cell was used for test reading of yarn in dry and
339
wet conditions. Gauge length was taken as 200mm
and Instron cross-head speed was kept at 100mm/min.
Average of twenty readings were taken. The test
results are given in Tables 2 – 6.
3 Results and Discussion
3.1 Tensile Properties of Fibres and Yarns
Table 1 shows that the tenacity of cotton fibre
increases to a great extent in wet conditions, whereas
in case of viscose fibre the tenacity drops to a great
extent in wet condition. In case of polyester staple
fibre, there is hardly any change in tenacity in wet
condition. As far as breaking elongation is concerned,
there is hardly any change in case of polyester and
viscose staple fibres, but in case of cotton, a
significant increase in breaking elongation is observed
in wet condition. It is a well-known fact that the
polyester and viscose fibres in wet condition loose
strength as compared to dry condition, while cotton
shows exactly opposite trend. The increase in tenacity
of cotton fibre in wet condition is due to the relief of
shear stress that can occur by untwisting and
unbending of the fibre. When the fibrils are bonded
together, the complex stress leads to early breakdown
but when they are free to move and release stress, the
fibre is strong9. In case of viscose staple fibre, the
drop in tenacity in wet condition is due to more
amorphous region and therefore the bonds are more
susceptible to be damaged by water molecule.
Fig. 1  Schematic diagram of experimental set-up
Table 1  Tenacity and breaking elongation of fibres in dry and wet conditions
Parameter
Tenacity, g/tex
Elongation-at-break, %
Dry
Polyester
Wet
% Change
Dry
Viscose
Wet
% Change
Dry
Cotton
Wet
% Change
6.02
14.9
6.03
15.0
2.89
11.80
1.92
12.0
3.47
6.8
4.42
9.5
+0.25
+0.67
Dry – Tested in dry condition; Wet – Tested in wet condition.
-33.6
+2.0
+27.6
+27.0
INDIAN J. FIBRE TEXT. RES., DECEMBER 2009
340
Polyester staple fibre does not show any significant
change in tenacity in wet condition due to very low
moisture absorption. But, when the tensile
characteristics of staple yarns in dry and in under
water conditions are considered, the mechanics are
not straight forward. The phenomenon of fibre
swelling, change in fibre-fibre surface friction due to
wetting, effect of hydrostatic forces, etc. play
significant role in addition to the change in fibre
characteristics on tensile characteristics.
3.2
3.2.1
Ring-spun Yarns
Effects of Fibre Type
Table 2 shows that in general the tenacity of yarns is
higher in wet condition, except in case of viscose
yarns. The significant drop in tenacity in case of
viscose staple fibre in wet condition is the basic
reason for drop in tenacity of viscose yarns. In case of
polyester yarn, tenacity in wet condition is more than
that in dry condition, which is due to the formation of
water film between the fibres in the yarns. Water film
enhances the fibre-fibre friction and generates stickslip phenomenon between the fibres in the yarn9. In
case of P/V blended yarns the combined effect of
above two phenomena play important role. In case of
cotton yarn, the tenacity increases significantly in wet
condition. It is also clear from Table 2 that in general
the increase in tenacity under water in polyester and
cotton yarns is more in case of finer yarn. This may
be due to the fact that more compact water film
friction is created between the fibre and the water
molecule of finer yarn. But, in case of other polyester-
viscose blended yarns, tenacity does not increase
significantly due to higher viscose fibre proportion in
the blended yarn.
Table 3 shows that in case of polyester and cotton
the breaking elongation of yarns increases while in
case of viscose and viscose-rich P/V blended yarns
the breaking elongation decreases in wet condition.
The increase in breaking elongation in case of
polyester is found to be marginal, whereas it is very
high in case of cotton yarns. This is mainly due to
higher breaking elongation of cotton fibre in wet
condition (Table 1). There are no definite trends in the
case of polyester/viscose blended yarns, which is due
to totally different nature of changes when the
polyester and viscose fibres are wet. In case of cotton
yarns, the increase in breaking elongation in wet
condition is higher for finer yarn.
Very interesting results are observed in case of
initial modulus of yarns in wet condition. Table 4
shows that in case of viscose and viscose-rich P/V
blended yarns, the increase in initial modulus is
found to be very high, whereas in the case of
polyester and cotton, there is moderate increase in
initial modulus of yarns in wet condition. It is also
observed that with the increase in fineness of yarns
the % increase in their initial modulus becomes
more in all the yarns, except in cotton yarn. The
twisting and bending effects will be easier when the
fibre is internally lubricated by absorbed water so
that fibrils can slide past one another. This is
probably the main reason why cotton fibre has
lower modulus when wet. Even in the simple
Table 2  Tenacity (cN/tex) of ring-spun yarns in dry and wet conditions
Linear
density
of yarns
Ne
Polyester
Dry
Wet
Polyester/Viscose
(65/35)
%
Change
Polyester/Viscose
(50/50)
Dry
Wet
%
Change
Dry
Wet
%
Change
20.31
(8.30)
23.91
(6.40)
+17.7
19.51
(7.31)
Viscose
Dry
Wet
Cotton
%
Dry
Change
Wet
%
Change
10s
31.7
(9.38)
32.9 +4.06
(6.13)
20.29
(4.96)
+3.99
14.64 8.37
(8.75) (11.49)
-42.8
15.34 19.82 +29.20
(4.36) (5.12)
20s
23.34
(9.19)
29.78 +27.5 20.80 23.51 +13.02 21.23 18.19
(8.50)
(13.07) (6.50)
(10.40) (5.92)
-14.3
14.97 9.84
(9.60) (14.80)
-34.2
13.75 20.36 +48.07
(5.28) (6.68)
30s
22.84 27.53 +20.5 18.67 20.77 +11.2
(13.35) (11.20)
(13.40) (12.10)
19.91 18.32
(9.88) (10.16)
-7.9
13.83 10.98
(10.06) (15.60)
-20.6
13.34 22.88 +71.5
(8.90) (9.31)
40s
21.91 27.32 +24.69 16.43 16.31
(14.26) (13.97)
(13.77) (6.40)
18.36 17.59
(10.80) (18.45)
-4.19
14.77 10.43
(12.30) (16.10)
-29.3
13.66 24.04 +75.9
(8.70) (8.89)
Values in parentheses indicate CV% of tenacity.
-0.73
DAS et al.: TENSILE CHARACTERISTICS OF YARNS IN WET CONDITION
341
Table 3  Breaking elongation (%) of ring-spun yarns in dry and wet conditions
Linear
density
of yarns
Ne
Polyester
Polyester/Viscose
(65/35)
%
Change
10s
12.13
(9.00)
12.63
(7.75)
+3.95
13.13 14.63 +11.4 13.56 14.17 +4.49
(7.36) (4.20)
(8.50) (5.80)
18.52 16.78 -9.93
(5.50) (14.12)
7.24
9.13 +26.1
(15.32) (13.85)
20s
11.89 11.96 +0.58 12.95 13.77 +6.33 13.05 13.93 +6.31
(9.46) (4.60)
(13.60) (11.18)
(12.40) (11.2)
17.08 17.33 +1.46
(8.02) (15..09)
6.82
8.92 +30.79
(15.21) (13.19)
30s
8.87
9.17
+3.38 12.50 12.67 +1.36 12.75 12.20 -4.3
(15.26) (13.62)
(10.32) (9.30)
(11.4) (10.32)
16.12 16.02 -0.62
(12.0) (16.10)
6.03
8.44 +39.96
(13.10) (11.80)
40s
11.81
(8.10)
14.34 13.18 -8.08
(12.1) (13.90)
5.59
8.21 +46.8
(13.10) (11.85)
10.60 10.28
(13.99) (9.94)
%
Change
-3.01
Dry
Wet
%
Change
11.29 10.27 -9.03
(7.25) (7.22)
Dry
Wet
Cotton
Wet
+2.70
Wet
Viscose
Dry
12.13
(9.37)
Dry
Polyester/Viscose
(50/50)
%
Change
Dry
Wet
%
Change
Values in parentheses indicate CV% of breaking elongation.
Linear
density
of yarns
Ne
Polyester
Dry
Wet
Table 4  Initial modulus (cN/tex) of ring-spun yarns in dry and wet conditions
Polyester/Viscose
Polyester/Viscose
Viscose
(65/35)
(50/50)
%
Change
Dry
Wet
%
Change
Dry
Wet
%
Change
Dry
Wet
%
Change
Cotton
Dry
Wet
%
Change
10s
254.85 271.62 +6.58 191.79 226.43 +18.06 176.43 287.93 +63.19 165.79 199.24 +20.17 164.45 242.17 +47.26
(8.90) (4.19)
(12.70) (12.70)
(10.52) (8.20)
(5.52) (13.45)
(6.69) (9.20)
20s
234.57 257.95 +9.96 216.17 275.98 +27.66 184.98 356.56 +92.75 206.11 270.78 +31.37 238.86 285.56 +19.55
(18.0) (13.20)
(15.83) (13.60)
(12.19) (12.20)
(4.15) (15.52)
(7.10) (10.97)
30s
333.42 388.86 +16.62 320.25 449.35 +40.31 287.69 601.18 +108.9 244.28 400.82 +64.08 250.57 297.53 +18.74
(30.38) (26.60)
(12.30) (8.75)
(12.03) (10.30)
(7.79) (20.46)
(11.32) (11.44)
40s
434.35 556.44 +28.10 539.53 962.46 +78.38 365.52 797.59 +118.2 285.75 707.31 +147.5 315.73 322.33 +2.09
(37.24) (33.80)
(13.54) (11.60)
(12.26) (7.60)
(8.65) (19.20)
(11.73) (11.90)
Values in parentheses indicate CV% of initial modulus.
extension of helical assembly, there is also a shear
deformation, which will be easier if the fibrils are
free of one another9.
Table 5 shows that the work of rupture increases in
wet condition for polyester yarn, whereas for viscose
yarn, there is a drop in work of rupture from marginal
to moderate level in wet condition. But, in case of
cotton, there is very high level of increase in work of
rupture in wet condition. This can be explained on the
basis of per cent change in tenacity and breaking
elongation of yarns in wet condition as compared to
that in dry condition. Very high level of increase in
the work of rupture of cotton in wet condition is
mainly due to the increase in both breaking elongation
and tenacity in wet condition. The trends for
polyester, viscose and P/V blended yarns can be
explained on the basis of changes in tenacity and
elongation of these yarns in wet condition.
3.2.2 Effects of Linear Density of Yarn
Effects of linear density of ring-spun yarns on
tenacity in dry as well as wet conditions are shown
in Table 2. It is observed that in case of polyester
and cotton, with the increase in yarn fineness the %
increase in tenacity is more in wet condition as
compared to that in dry condition. However, in case
of viscose and viscose-rich P/V blended yarns, the
tenacity decreases in wet condition and there are no
specific trends with the change in yarn fineness.
This may be due to the fact that more compact
INDIAN J. FIBRE TEXT. RES., DECEMBER 2009
342
Table 5  Work of rupture (cN/tex) of ring-spun yarns in dry and wet conditions
Linear
density
of yarns
Ne
Polyester
Dry
Wet
Polyester/Viscose
(65/35)
%
Change
Dry
Wet
%
Change
Polyester Viscose
(50/50)
Dry
Wet
%
Change
Viscose
Dry
Wet
Cotton
%
Change
Dry
Wet
%
Change
10s
268.01 270.75 +1.02 177.07 227.59 +28.53 115.31 124.34 +7.83
(14.70) (16.97)
(10.89) (15.72)
(9.52) (6.59)
74.68 73.18
(7.8) (6.73)
-2.10
37.32 87.43 +134.2
(8.65) (9.31)
20s
89.35 113.01 +26.48 74.55 92.95 +24.68 67.06 70.87
(13.60) (17.50)
(20.35) (13.08)
(10.90) (9.20)
+5.68
67.04 56.21
(5.50) (5.32)
-16.1
25.51 57.78 +126.5
(9.76) (16.19)
30s
43.75 67.99 +55.4 47.62 55.75 +17.07 53.95 44.05 -18.3
(13.30) (16.31)
(15.20) (13.62)
(17.20) (13.30)
33.70 29.20
(4.36) (3.10)
-13.3
16.47 39.00 +136.8
(12.26) (12.60)
40s
43.16 44.63 +3.40 29.98 35.50 +18.41 32.46 30.88 -4.86
(6.13) (13.07)
(16.90) (17.08)
(13.32) (10.35)
28.83 24.03 -16.64 13.17 29.44 +123.53
(5.40) (2.40)
(14.80) (15.37)
Values in parentheses indicate CV% of work of rupture.
water film friction is created between the fibre and
the water molecule of finer yarn.
It is observed from Table 3 that in all the yarns,
except for cotton yarns, there is not much change in
yarn breaking elongation in wet condition as
compared to that in dry condition. In case of cotton
yarns the breaking elongation increases significantly
in wet condition. This is mainly due to the higher
breaking elongation of cotton fibre in wet condition.
Table 3 also shows that in case of cotton, the per cent
increase in breaking elongation increases with the
increase in yarn fineness. As already explained, this
may also be due to the formation of water film which
enhances fibre-fibre friction and thus reduces fibre-tofibre sliding.
It is clear from Table 4 that initial modulus of all
the yarns increases in wet condition as compared to
dry yarn, irrespective of the type of material and
blend proportion. This may be due to the fact that in
wet condition, water film forms inside the yarn
structure, which enhances the fibre-fibre friction and
thus resists initial deformation. It is also interesting to
observe that in case of cotton yarns, with the increase
in yarn fineness, the % increase in initial modulus of
yarn reduces in wet condition as compared to that in
dry condition, but for all other yarns the trends are
just opposite.
It is observed from Table 5 that the work of
rupture of cotton and polyester yarns increases in
wet condition, whereas in case of viscose yarns the
trend is just opposite due to the reason as explained
above. No specific trends are observed in case of
viscose-rich P/V blended yarns. It is also observed
from Table 5 that the yarn fineness has no specific
effect on the per cent increase in work of rupture of
yarns.
3.3 Rotor-spun Yarns
3.3.1 Effect on Yarn Tenacity
It can be observed from Table 6 that irrespective of
fineness of yarn, the yarn tenacity under water is
always higher than that of dry yarn. No specific trend
on per cent change in yarn tenacity in wet condition is
observed when the linear density of rotor yarns is
changed. The trend is exactly the same as that for
ring-spun yarns and the reason has been explained
earlier.
3.3.2 Effect on Yarn Breaking Elongation
It is evident from Table 6 that for all the yarn linear
densities, the breaking elongation of yarn under water
is always higher than that of dry yarn. The trend is
exactly the same as that for ring-spun yarns due to the
reason as explained earlier. No specific trend on the
per cent change in breaking elongation of yarn in wet
condition is observed when the linear density of rotor
yarns is changed.
3.3.3 Effect on Yarn Initial Modulus
It is clear from Table 6 that the initial modulus of
yarns in wet condition is always higher than that of
dry yarn. The trend is exactly the same as that for
ring-spun yarns due to the reason as explained earlier.
DAS et al.: TENSILE CHARACTERISTICS OF YARNS IN WET CONDITION
343
Table 6 Tensile property of open-end yarns of different fineness in dry and wet conditions
Yarn parameter
7s Ne yarn
8s Ne yarn
10s Ne yarn
12s Ne yarn
Dry
Wet
%
Change
Dry
Wet
%
Change
Dry
Wet
% Change
Dry
Wet
%
Change
Tenacity
11.63
16.03
37.83
12.08
16.68
38.08
12.52
16.77
33.94
12.84
16.89
31.54
cN/tex
(6.6)
(6.3)
(8.5)
(7.87)
(8.75)
(8.06)
Elongation at
break, %
8.27
12.59
8.93
12.66
8.89
13.12
(5.06)
(13.8)
(6.20)
(7.01)
127.9
242.4
144.1
333.6
(4.85)
(16.00)
(5.30)
(13.96)
59.43
103.5
48.16
89.63
(9.11)
(14.70)
(5.96)
(5.60)
Initial modulus
cN/tex
Work of
rupture, N.mm
(4.9)
(15.4)
131.9
143.7
(8.75)
(8.00)
67.63
133.8
(9.06)
(6.80)
(6.8)
(5.3)
52.23
9.70
12.46
(5.6)
(8.6)
8.95
122.9
158.5
(5.20)
(6.70)
80.01
125.8
(6.48)
(13.06)
97.84
28.45
28.96
57.23
41.76
89.52
74.15
47.58
131.51
86.10
Values in parentheses indicate CV%.
Also, it is very clear that the per cent increase in
initial modulus increases rapidly as the yarns become
finer.
3.3.4 Effect on Work of Rupture
It is evident from Table 6 that for all the yarn linear
densities, the work of rupture of yarn under water is
always higher than that of dry yarn. The trend is
exactly the same as that for ring-spun yarns due to the
reason as explained above. No specific trend on the
per cent change in breaking elongation of yarn in wet
condition is observed when the linear density of rotor
yarns is changed.
4 Conclusions
4.1 The tenacity of ring-spun yarns is higher in
wet condition as compared to that of dry yarn for
all the yarns, except for viscose yarns where
tenacity drops in wet condition. The increase in
tenacity in case of cotton is much higher than that
of polyester and P/V blended yarns. In general, the
increase in tenacity under water for polyester and
cotton yarns is more in the case of finer yarn. For
polyester and cotton, with the increase in yarn
fineness the per cent increase in tenacity in wet
condition enhances as compared to yarn tenacity in
dry condition.
4.2 In case of polyester and cotton, the breaking
elongation of ring-spun yarns increases, while in
viscose and viscose-rich P/V blended yarns the
breaking elongation decreases in wet condition.
For cotton yarns, the increase in breaking
elongation in wet condition is higher in case of
finer yarn.
4.3 In viscose and viscose-rich P/V blended ringspun yarns the increase in initial modulus is found to
be very high, whereas in case of polyester and cotton,
there is moderate increase in initial modulus of yarns
in wet condition. In case of cotton yarns, with the
increase in yarn fineness the % increase in initial
modulus of yarn reduces in wet condition as
compared to dry yarns, but for all other yarns the
trends are just opposite.
4.4 In case of polyester ring-spun yarn, work of
rupture is increased and in case of viscose ringspun yarn, there is drop in work of rupture from
marginal to moderate level in wet condition. But in
case of 100% cotton ring-spun yarns, there is very
high level of increase in the work of rupture in wet
condition.
4.5 In case of cotton rotor yarn, the tenacity,
breaking elongation, initial modulus and work of
rupture under water are higher than that of dry yarn.
Industrial Importance: There are many applications
in which the textile materials are used in wet
condition such as swim wear, rain wear, etc. This
paper describes the characteristics of different types
of yarns with various blend proportions used in such
applications. Hence, the industry will get some
guidelines in selecting the materials for the production
of these products and optimize the blend proportion as
per the requirement.
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