Indian Journal of Fibre & Textile Research Vol. 27, March 2002, pp. 72-76

Evaluation of comfort properties of polyester-viscose suiting fabrics

A Mukhopadhyay", I C Sharma & Mukesh Sharma

The Technological Institute of Textile & Sciences, Bhiwani 1 27 021 , India

Received 30 August 2000; revised received and accepted 31 January 2001

The comfort properties of polyester-viscose blended fabrics of two different structures (plain and twill) have been studied. It is observed that with the change in polyester content, the total hand valUe (THV) of twill woven fabrics shows different trend than that of plain woven fabrics. The thermal insulation and water-vapour resistance increase with the increase in polyester content. It is found that the fabric having the best THV may not be comfortable in all aspects.

Keywords : Fabric comfort, Fabric handle, Fukurami, Koshi, Numeri, Thermal insulation, Total hand value, Water-vapour resistance

1 Introduction The term comfort is a nubulous one which defies

definition, but the sensation of comfort is easily recognized by the person who experiences it. Many attempts have been made to define the state in physical terms. The clothing comfort is dependent upon the low-stress mechanical, thermai and moisture transfer properties of the fabrics. The general subject of fabric sensory property influenced by low-stress mechanical properties of the fabric is reviewed by Bishopl . There is a general agreement that the movement of water vapour and heat through a garment is probably the most important factor in clothing comfort2. It has been suggested3,4 that the thickness is the single most important factor in determining thermal resistance. The utJity of moisture transfer properties on fabrics has also been reported earliers.7. Sreenivasan et al. 8 analysed the effect of polyester and cellulosic fibre contents on the moisture transfer time of fabrics. A very few information is available about the effect of blend on fabric comfort. In the present work, the effect of blend proportion on the comfort properties of polyester­viscose blended suiting fabrics has been studied.

2 Materials and Methods 2.1 Materials

Polyester-viscose blended yarns of four different

3 To whom all the correspondence should be addressed. Phone : 293301 -02-03; Fax : 009 1 -0 1 8 1 -293653, 29 1 120; E-mail : arunangshu_recj @rediffmail .com Present address : Department of Textile Engineering, Regional Engineering College, Jalandhar 1 44 0 1 1

blend proportions (40:60, 48 :52, 65 :35 and 75:25) were used for preparing plain and 212 twil l suiting fabrics. The yarn linear density and twist per inch were 2/1 6 tex and 1 7 .6 respectively. The ends and picks per inch of plain fabrics were 60 and 52 respectively . Twill fabrics possess 76 ends/inch and 56 picks/inch. All the fabrics were heat-set on Primatex stenter at 20 mlmin speed with 3 % overfeed allowing 5. 1 % width-wise shrinkage at 1 80°C.

2.2 Methods Low-stress mechanical properties of the fabrics

were examined using KES-F system. The mechanical properties were compared on the basis of t-test at 95% significance limit. Hand values and total hand value were derived by the software using the following conversion equations for winter suitings9:

}6 X . - X i Y :::R Co + I Ci ---'-.'_-i:} Ui where Y is the hand value; Xi, the ith characteristics value or its logarithm; Xi and 0;, the mean value and the standard deviation of the ith characteristics value; Co , the constant; and Ci, the coefficient.

Table 1 shows the constants and coefficients of the equations. The fol lowing equation was used for the total hand values (THY) THY=

3 Co+ I [Cil (Yi - Mil )/ull + (C,2 (Y/ - M i2 )/ U i2 ]

j:l where Yi is the hand values of the ith primary hand; Mil and Mi2., the mean values of Yi and Y/

MUKHOPADHYAY et al. : COMFORT PROPERTIES OF POLYESTER-VISCOSE SUITING FABRICS 73

Table 1 - Parameters of equations for translating mechanical values into hand values of men's winter suiting fabric

Xi X Oi Cj Koshi Numeri Fukurami

0 5.7093 4.7533 4.9799 I LT 0.6082 0.06 1 1 -0.03 17 -0.0686 -0. 1558 2 log WT 0.962 1 0. 1 270 -0. 1 345 0.0735 0.2241 3 RT 62. 1 894 4.4380 0.0676 -0. 1 6 1 9 -0.0897 4 10g B - 1 .0084 0. 1 267 0.8459 -0. 1658 -0.0337 5 log 2HB - 1 .3476 0 . 180 1 -0.2 1 04 0 . 1083 0.0848 6 log G -0.0 143 0. 1 287 0.4268 -0.0263 0.0960 7 log 2HG 0.0807 0. 1 642 -0.0793 0.0667 -0.0538 8 log 2HG5 0.04094 0. 1 44 1 0.0625 -0.3702 -0.0657 9 LC 0.3703 0.0745 0.0073 -0. 1 703 -0.2042 1 0 log WC -0.7080 0. 1427 -0.646 0.5278 0.8845 1 1 RC 56.2709 8.7927 -0.004 1 0.0972 0. 1 879 12 MIU 0.2085 0.02 1 5 -0.0254 -0. 1 539 -0.0569 1 3 log MMD - 1 .8105 0. 1 233 0.0307 -0.9270 -0.5964 14 log SMD 0.6037 0.2063 0.0009 -0.303 1 -0. 1 702 1 5 log T -0. 1 272 0.0797 -0. 1 7 1 4 -0. 1 358 0.0837 16 log W 1 .4208 0.059 1 0.2232 -0.0122 -0. 1 8 1 0

Xi - the ilb characteristics value or its logarithm, X and Oi - the mean value and the standard deviation of the ilb characteristic value, and Cj - coefficient.

Table 2 - Parameters of the HV-THV translation equations

Yi Cil Ci2 Mil Mi2 Oil 0i2 I Koshi 0.6750 -0.5341 5.7093 33.9032 1 . 1434 1 2. 1 1 27 2 Numeri -0. 1 887 0.804 1 4.7537 25.0295 1 .5594 1 5.562 1 3 Fukurami 0.93 1 2 -0.7703 4.9798 26.9720 1 .4741 1 5 .2341

Yi - Hand value of the i1h primary hand. Cil and Ci2 - coefficients. Mil and Mi2 - mean values of Yi and Y/. and Oil and Oir standard deviations of Yi and Y/ respectively.

respectively; Oi, and 0i2, the standard deviations of Yi and Y/ respectively; Co, the constant; and Ci/ and Ca, the coefficients as shown in Table 2.

Thermal insulation was determined by using the KES-FS (Thermo lab - II). The dry contact method7

with an air velocity of 30 cm/s was used for the measurement of thermal insulation. The modified evaporation cup method7 was used to measure the resistance of the fabric to water vapour.

3 Results and Discussion 3.1 Effect of Blend Proportion on Low-stress Mechanical

Properties of Fabric 3.1.1 Tensile Properties

Table 3 shows that the fabric extensibility (EM) decreases with the increase in polyester content in polyester-viscose blended fabrics. Fabric extensibility is likely to be governed by the bending rigidity and the contact area of the warp and weft yams 10. The higher bending rigidity of polyester and more

compact structure of polyester-rich fabrics result in the lower fabric extensibility. It is further observed that the tensile energy (WC) decreases with the increase in polyester content. This is due to the lower extensibility of the polyester-rich fabrics. The linearity of stress-strain curve (LT) does not show any specific trend with the increase in polyester content. It is again observed that with the increase in polyester content, the tensile resiliency (RC) increases. It may be due to the higher resiliency of polyester fibre compared to that of viscose fibre.

3.1.2 Bending Properties Table 3 shows the effect of blend proportion on the

bending behaviour of polyester-viscose blended fabrics. It is observed that with the increase in polyester content the bending rigidity (B) increases. It may be attributed to the higher flexural rigidity of polyester fibre and the compact structure of polyester­rich fabrics. The compact structure of the fabric

74 INDIAN J. FIBRE TEXT. RES., MARCH 2002

Table 3 - Effect of blend proportion on low-stress mechanical properties of polyester-viscose blended fabrics

Properties 2/2 Twill

40P:60V 48P:52V 65P:35V

Tensile

EM,% 4.97 4.29 4.01

LT 0.67 0.68 0.65

WT, gf cmlcm2 8.42 7.45 6.7 1

RT, % 43.63 47.49 49. 1

Bending

B, gf cm2/cm 0.0701 0.0728 0.0775

2HB, gf cm/cm 0.0523 0.0562 0.0647

Shear

G, gf cm.deg 0.50 1 0.558 0.62 1

2HG, gf/cm 0.940 0.990 1 . 1 8

2HG5, gf/cm 2.0237 2.2295 2.8640

Compression

LC 0.306 0.301 0.303

WC, gf cmlcm2 0. 1 54 0. 1 5 1 0. 146 RC, % 75.05 76.73 79.29

Surface

MIU 0.208 0.2048 0.2045

MMD 0.01 0.009 0.0 12

SMD, J..lm 2.98 2.92 2.58

P - Polyester, V - Viscose

prevents the relative motion of the fibres during the bending of the fabrics, resulting in the higher bending rigiditi I. The hysteresis of bending (2HB) also increases with the increase in polyester content, which is also attributed to the compact structure of polyester-rich fabrics.

3.1.3 Shear Properties Table 3 shows the effect of blend proportion on the

shear behaviour of blended fabrics. It is observed that the shear stiffness (G) increases with the increase in polyester content. This may be attributed to the compact structure of the fabric having higher polyester content and the higher flexural rigidity of the polyester fibre compared to that of viscose. Subramanium et al. 12

found that the contact between the threads greatly affects the shear rigidity of the fabrics. The compact structure results in greater contact area between the threads which is responsible for the higher shear rigidity of the fabric having higher polyester content. The hysteresis of shear (2HG) also increases with the increase in polyester content which is attributed to the compact structure of fabric.

3.1.4 Compressional Properties Table 3 shows the effect of blend proportion on the

compressional behaviour of polyester-viscose blended

Plain

75P:25V 40P:60V 48P:52V 65P:35V 75P:25V

3.55 4.61 4.29 4.01 4.01

0.69 0.7 1 0.72 0.75 0.75

5.76 8. 1 3 7.5 1 7.50 7.49

54.48 54.57 54.92 55. 1 0 56.9 1

0.09 1 7 0.0644 0.0679 0.0757 0.0933

0.0791 0.05 1 2 0.0547 0.0697 0.09 1 2

0.820 0.944 1 .096 1 .493 1 .929 1 .528 1 .630 1 .8 1 1 2 .307 3.020

3 .9028 4.4467 4.9267 6.7057 8.4770

0.268 0.309 0.285 0.308 0.28 1

0. 1 34 0. 1 62 0. 1 44 0. 14 1 0. 1 3 1

82.76 68.06 70. 1 2 72.54 75.24

0.203 0.203 0. 1 96 0. 1 93 0. 1 89 0.0 1 1 0.0 1 9 0.D l8 0.01 9 0.01 7 2.50 7. 1 3 7.09 6.56 6.49

fabrics. It is observed that the linearity of compression (LC) curve does not show any specific trend with the increase in polyester content. It is further observed that with the increase in polyester content, the compres­sional energy (WC) decreases. This may be attributed to the smoother rod-like structure of polyester fibre. When the fabric is compressed by compression ele­ment, the warp and weft yarns tend to be flattened which is governed by the fibre-to-fibre slippage. There­fore, as the polyester content increases, the fibre-to­fibre slippage during the compression also increases, resulting in the lower value of compressional energy. It is also observed that the compressional resiliency (RC) increases with the increase in polyester content. This may be attributed to the higher resiliency and lower fibre-to-fibre friction of polyester compared to that of viscose.

3.1.5 Surface Properties Table 3 shows that the coefficient of friction (MIU)

decreases with the increase in polyester content, which is attributed to the smoother surface of polyester fibre compared to that of viscose fibre. Mean deviation of coefficient of friction (MMD) does not show any specific trend with the increase in polyester content. It is further observed that the

MUKHOPADHYAY et al. : COMFORT PROPERTIES OF POLYESTER-VISCOSE SUITING FABRICS 75

Table 4 - Effect of blend proportion on total hand value, thermal insulation and water-vapour resistance of polyester-viscose blended fabrics

Structure Blend ratio Koshi Numeri (polyester/viscose) (stiffness) (smoothness)

212 Twill 40:60 2.82 7.33

212 Twill 48:52 2.69 7.25

212 Twill 65:35 3.65 6.42

212 Twill 75:25 4.56 5.88

Plain 40:60 3.76 3.74

Plain 48:52 4.23 3.47

Plain 65 :35 4.78 3. 10

Plain 75:25 5.69 2.99

geometrical roughness (SMD) decreases with the increase in polyester content.

3.2 Effect of Blend Proportion on Hand Values of Fabrics 3.2.1 Koshi (Stiffness)

Table 4 shows the effect of blend proportion on the hand values of polyester-viscose blended fabrics. It is observed that with the increase in polyester content, the fabric Koshi value increases. This may be attributed to the increase in bending rigidity, shear rigidity and tensile resiliency, and decrease in tensile energy and compressional energy9.

3.2.2 Numeri (Smoothness) Table 4 shows that with the increase in polyester

content, the fabric Numeri decreases. The mean deviation of coefficint of friction (MMD) has the dominant effect on Numeri value but, in the present study, MMD does not show any significant change. The decrease in Numeri value may be attributed to the decrease in compressional energy and increase in tensile resiliency, bending rigidity, shear rigidity and hysteresis of shear9.

3.2.3 Fukurami (Softness and Fullness) Fukurami value decreases with the increase in

polyester content. This may be attributed to the decrease in compressional energy and tensile energy, and increase in bending rigidity, 2HG and 2HG5.

3.2.4 Total Hand Value (THV) It is observed from Table 4 that in case of twill

woven suiting fabrics, the total hand value decreases with the increase in polyester content. The 40:60 polyester-viscose blend shows the best THV. In case of plain woven suiting fabrics, with the increase in polyester content the total hand value does not show any significant change initially but at 75 :25 polyester­viscose blend ratio, THV shows the best value.

Fukurami (fullness Total hand Thermal Relative water-and softness) value insulation, % vapour resistance

6.37 3.94 1 2.07 0.084

6.65 3.84 12.93 0.086

5.85 3.65 12.98 0.090

5.54 3.56 13 .79 0.098

4.49 2.45 1 0.7 1 0.086

4. 1 1 2.42 1 1 .6 1 0.087

4.07 2.44 1 2.93 0.090

4.05 2.58 1 5.52 0.099

However, the change in THV is small with the change in blend proportion.

3.3 Effect of Blend Proportion on Thermal Insulation of Fabrics

It is observed from Table 4 that with the increase in polyester content, the thermal insulation increases. This may be attributed to the greater thickness of the fabric having higher polyester content.

3.4 Effect of Blend Proportion on the Water-vapour Resistance

Table 4 shows that with the increase in polyester content, the water-vapour resistance of fabric i ncreases. This may be attributed to the compact structure of polyester-rich fabrics7 and lower moisture regain of polyester fibre compared to that of viscose fibre.

3.5 Comfort of Blended Fabrics

It is observed that the fabric having the best THV may not possess higher thermal comfort. In twill woven suitings, the best THV is shown by 40:60 polyester-viscose blend, but the fabric has minimum thermal insulation. While in case of plain woven fabrics, the best THV is shown by 75 :25 polyester­viscose blend but the fabric from the above blend possesses the minimum value of water-vapour transfer.

4 Conclusions

4.1 Koshi value increases with the increase in poly­ester content in the fabric but Numeri and Fukurami values decrease with the increase in polyester content. 4.2 In 212 twill woven suiting fabrics, the total hand value (THV) decreases with the increase in polyester content while in plain woven fabrics the THV does not show any significant change initially with the increase in polyester content but at 75 :25 polyester­viscose blend ratio it shows the best value. However, the change in THV is small with the change in blend.

76 INDIAN 1. FIBRE TEXT. RES., MARCH 2002

4.3 Thermal insulation and water-vapour resistance increase with the increase in polyester content. 4.4 It is observed that the fabric having the best THY value may not be comfortable in all aspects.

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