Indian Journal of Fibre & Textile ResearchVol. 22, June 1997, pp. 99-111

Studies on low-stress mechanical properties of polyester/cottonsuiting fabrics

V Natarajan, G Thilagavathi & V Sankaran:'Department of Textile Technology, PSG College of Technology, Coimbatore 641004, India

Received 1 May 1996; accepted 24 February 1997

The effects of different stages of finishing such as scouring, mercerisation, heat-setting, polyesterdyeing, cotton dyeing and finishing on low-stress mechanical properties of polyester-cotton suitingfabrics have been studied. It is observed that the finished fabrics have tensile energy, tensile resili-ence and elongation of the order of the grey fabric, but smaller bending and shear values. In general,scouring and dyeing soften the fabrics, resulting in smaller bending and shear values, whereas mer-cerisation and heat-setting stiffen the fabrics, resulting in higher values. On the contrary, yarn bend-ing rigidity and hysteresis values after dyeing are higher compared to those after rnercerisation andheat-setting. This shows that the structural changes have played far greater role in deciding the fa-bric properties.

Keywords: Finishing, Kawabata fabric evaluation system, Low-stress mechanical properties,Polyester-cotton fabric, Suiting fabric

1 Introduction

Studies have established that handle, comfort,tailorability and garment formability, and appear-ance depend on the low-stress mechanical pro-perties such as bending, tensile and shear at lowstress levels!". Kawabata evaluation system for fa-brics (KES-FB) measures the surface properties inaddi tion to above properties I ,2.7. Fabric selectionfor tailoring, selection of sponging process beforetailoring and the formulation of tailoring instruc-tions are carried out on the basis of low-stressmechanical properties+":". Fibre composition,spinning and twisting, weave structure and weav-ing, and finishing processes are altered to achievefabric properties close to the specifications interms of low-stress mechanical propertiesv'"!',Analysis of winter suiting samples used in stan-dardization of total hand value has shown thatyarn properties and yarn geometry in fabric aredifferent for the fabrics with excellent handle andthose with poor handle". It has been observed'?that finishing process would affect the "SHARI"handle (a feeling of crispness) of summer suitingsup to 10%, Men's summer suiting fabric haveshown smaller values for tensile, bending and

·Present address: National Textile Corporation (TN & P) Ltd.Coimbatore 641009, India

shear characteristics in finished state compared togrey state':',

Therefore, in this work, studies have been con-ducted on low-stress mechanical properties ofpolyester/cotton suiting fabrics and how theseproperties change in different stages of finishing.Attempts have also been made to identify whetherthese changes in properties are due to change inyarn property itself.

2 Materials and MethodsTwo suiting fabrics with particulars given in

Table 1 were used in the study. Chemical pro-cessing conditions and recipes are given in Tables2-4. Test methods, instruments and number of

Parameter

Table I-Fabric production parameters

Fabric I Fabric 2(Spun x Spun (Spun x Filament

Suiting) Suiting)2/30 s 67/33 PIC 2/30 s 67/33 PIC2130 s 67/33 PIC 300 d polyester

60 8460 84

Plain 1/2 TwillCIMMCO CIMMCO

Warp countWeft countEnds/in.Picks/in.WeaveLoom type

Loom widthRPM

automatic68 in.145

automatic68 in.145

100 INDIAN J. FmRE TEXT. RES., JUNE 1997

Table 2-Fabric desizing, scouring and mercerising conditions

Chemicals used Temp. & duration Speed(Tension/Slack)

100 mlmin(Slack)

Processing stage

Desizing Anilozyme GH, 7 g/LCommon salt, 7 g/LUltra NC, 0.5 g/LpH adjusted withacetic acid to 5.5300 L bath in JumboJigger for 1200 mBleach liquor, 6 g/LHydrogen peroxide, 2 kgStabilizer AWNI, 0.15 kgSoda ash, 2 kgFlash bleach, I kgAcetic acid, ILCaustic soda lye,

260-300 gIL (48-52° Tw)

Scouring

Mercerising

Washing/Dryingafter processing

50-55°C

i.ih

SO°CI.5h

Dyringincylinder

Table 3-Heat setting and dyeing conditions for 75/25polyester Icotton suiting fabric

Process Material used Temp. & Afterduration processing

dryingHeatsetting"

75/25 PICOverfeed, 3-4%

193°C

Polyesterdyeing

75125 PICHAL FaronNaviline Blue GL, 90 gTulestron Fast Brown3 Rd,65 gTulestron Fast YellowBrown GRC, 70 gSodium acetate, 500 gAcetic acid, I L(3.2 kg/cm-)

20 min

130°C Drying incylinder

Cottondyeing

75125 PICJig (Pad &Deve/op)Novatie Olive D SID, 0.9 g 55°CNovatie Brown R SID, 2gNavinon Olive GreenB UIO,0.3gCaustic 70· Tw, 10 LHydros, 3 kgHydrogen peroxide, 1 LAcetic acid, 0.5 LSoap, 100 gSoda ash, 400 g

Drying incylinder

Finishing 75125 PICSuitingAcetic acid, 1 LResin with built-incatalyst, 40 gAminosilicone, 20 gPolyethylene emulsion(10%),15 gCopolymer, i.ig

'Speed, 25 mlmin

170·CISO°C

Drying incylinder

15 mlmin Drying incylinder

Table 4-Heat setting and dyeing conditions for 67/33polyesterlcotton suiting fabric

Process Material used Temp. & Afterduration processing

dryingHeatsetting" 67/33 PIC 199°C

Polyester' 671.33 PC CSIF Khakiedyeing Dispersol Blue GL, 190 g

Tulestron Fast Brown3Rd, 100 gTulestron Fast Yellow BrownGRC,4DOgSodium acetate, 500 gAcetic acid. I L(3.2 kg/cm+)

671.33 PICJig(Pad &Devel-op)Novatie Olive D SID, 4 g 55°CNovatie Brown R SID, 4 gNavinon Gold Orange3G SID, 0.13 gCaustic 70"Tw, 10 LHydros,3 kgHydrogen peroxide, 1 LAcetic acid, 0.5 LSoap, 100 gSoda ash, 400 g

130·C20 min

Cottondyeing

Finishing 67133 CISF KhakiAcetic acid, 1 LResin with built-in catalyst,60 gAminosilicone, 30 gPolyethylene emulsion(10%),20 g

'Speed, 25 m/min

170·CIi.iO°C

Drying incylinder

Drying incylinder

Drying incylinder

NATARAJAN et al.: POLYESTER/COTION SUITING FABRICS

samples/test are listed in Table 5, and the testingconditions are given in Table 6.

The sample fabrics were manufactured in auto-matic shuttle loom (47 in. wide) under normalmill working conditions at a speed of 145 rpmand were finished in a sequence of scouring, mer-cerisation, heat-setting, polyester dyeing, cottondyeing and finishing.

The samples were collected for testing at all thestages of finishing and were subjected to the testslisted in Table 5.

2.1 Yarn Bending TestKES-FB2 bending tester was used to study the

bending properties of yarn samples taken from fa-brics. Standard test conditions were maintained.Eighty threads were mounted in a paper templatewith 10 mm gauge length. The threads were fixedparallel to each other without touching one an-other and were pasted to the paper template witha cellotape. The tests were carried out in yarntesting mode.

3 Results

3.1 Tensile PropertiesThe tensile characteristics of spun x spun suit-

ing (Fabric 1) and spun x filament suiting (Fabric2) at every stage of chemical processing areshown in Figs 1-4. Values in warp and weft direc-tions are shown separately.

3.1.1 Elongation at Preset LoadIt IS observed in chemical processing that for

fabric 1, the elongation at a preset maximum loadof 500 gf/cm decreases from 3.5% to 2.1% inwarp direction and increases from 2.1% to 3.6%in weft direction. An exactly opposite trend is ob-served for fabric 2 where the elongation increasesfrom 1.7% to 2.6% in warp direction and dec-reases from 3.9% to 2'(}% in weft direction (Fig.1).

101

Elongation for fabric 1 in warp direction dec-reases in scouring, marginally increases in the fol-lowing processes and then again decreases in cot-ton dyeing and finishing. But, in weft direction, amultifold increase in elongation is observed inscouring and mercerisation to reach a value of6.8% in mercerisation. However, heat-setting andpolyester dyeing brings down the value signifi-cantly and improvement in cotton dyeing is againlost in finishing. In Fabric 2, a decrease in elonga-tion in warp direction is observed in scouring,mercerisation and cotton dyeing, and increase isobserved in heat-setting, polyester dyeing and fin-ishing. In weft direction, improvement in elonga-tion is observed in scouring, mcrccrisation, po-lyester dyeing and cotton dyeing, whereas a dec-rease in elongation is observed in heat-setting andfinishing.

Elongation values greater than 3.5'1<,in warp di-rection and a slightly higher elongation in weft di-

Test Instrument used

Table 5- Test methods employed and instruments used

No. of tests

Ends/in; Picks/in Pick counting glass \0 readings/sample10 readings/sample

20 readings/sample2 samples2 tests/sample2 samples2 tests/sample2 samples2 tests/sample20 readings/sample2 template(HOthreads each)2 tests/sample

Warp and weft lineardensity

Cut and weighmethod (Microbalance)Shirley crimptesterKES-FBI tensiletesterKES-FB7. bendingtesterKES-FB I sheartesterInstron tester

Table 0- Testing conditions

Fabric tensile Fabric shear Fabric bending Yarn tensile Yarn bendingtest test test test test

Instrument KES-FBI KES-FBI KES-FBI Instron KES-FB2Sample width 20cm 20cm 20cm Single thread 80 threadsGauge length 5cm Scm I em 5cm IcmTest rate 0.2 mm/s Smm/J2s 0.5 cmI/s lOcm/min O.Scm-l/sTest cycle Max. load + go shear ± 2.5 cm-I Break test ±2.S cm-I

SOOgf/cm angle curvature curvatureTest load 10 gf/cm

Warp and weftcrimpFabric tensilebehaviourFabric bendingbehaviourFabric shearbehaviourYarn tensilebehaviourYarn bendingbehaviour

KES-FB2 bendingtester

102 INDIAN J. FIBRE TEXT. RES., JUNE 1997

rection are preferable for trouble-free tailoringand good suit appearance". Polyester/cotton fabricis obviously expected to have less elongation at agiven load. Fabric I is expected to yield garmentwith better appearance.

zo 1·5~~~~-u~~~~~~~~~~L-~~~~~~8

.14;---~'7~/)=)~P=Ol=Y=E5=T=ER~/~C=O~TT=OH--5-UI=TI-N-'------------------------~

1210

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~ 14w 12~ 10c.n~ 8t- G

42O~~~~~~~-L~~~~-L~L-~~

.,:25•..

3.1.2 Linearity of Tensile Curve,Since different chemical processes soften the fa-

brics, the material starts to deviate more andmore from a flexible sheet, thus yielding lower va-lues of linearity (Fig. 4).

7·5'-~,~,~,,7)~p~Ol~y7E5~I~ER~/~C-O~"-O-N-S-U-II-IN-G--------------c::J----W-.-R-P--,

6·5 I22Zl WEFT

5·5

4·5

3·5

G

4

2

FINISHEDSTAGES OF FINISHING

Fig. I-Elongation at preset load of SOOgf/cm

PET DYED COTTON DYED FINISHED

STAGES OF FINISHING

Fig. 2- Tensile energy

NATARAJAN ('I al.: POLVESTER/COTTON SUITING FABRICS 103

In fahrie I, the rmrurnurn linearity i" observedin warp diretion after heat-setting and that in weftdirection after mereerisation. As expected, the fi-nal finishing process stiffens the fabric, leading toslightly higher linearity value than the minimum.

>~~ 0·70~~~~~~~~~~~~~~~~~~~~~ 0·85

605856

0~n 54

wu 52zw-l 50If) 65UJ0:W 60-l

v=;z 55UJ~

50

0-90

0·85

0·80

0-75

....J

0-80

0-75

In fabric 2, the linearity increases in rncrcerisa-tion and heat-setting after the initial decrease inscouring. However, marked decrease is observedin dyeing processes.

67133 POLYESTER 1 COTTON SUITING c=J WARP

~WEn

Fig. 3- Tensile resilience

67/33 POLYESTER ICOTTON SUITING ~WARP

~WEFT

FINISHED

STAGES OF FINISHING

Fig. 4-Linearity of tensile curve

104

3.1.3 Tensile Energy

INDIAN J. FIBRE TEXT. RES., JUNE 1997

creases in scouring, retained till polyester dyeingand then decreases in cotton dyeing and finishing(Fig. 3).

3.2 Bending Properties

Figs 5 and 6 show the bending rigidity and hys-teresis of bending respectively for fabrics 1 and 2.Bending rigidity index values (defined as the ratiobetween the measured bending rigidity value ofthe fabric and that calculated from yarn bendingrigidity) are shown in Fig. 13.

3.2.1 Bending Rigidity

Bending rigidity of fabrics 1 and 2 (Fig. 5) inboth warp and weft directions undergoes similarchange in finishing processes. Rigidity decreasesto a minimum level in scouring, increases to amaximum value in heat-setting, decreases again inpolyester dyeing and finally increases to reach avalue smaller than that for grey state in fabric 1(weft direction) and fabric 2 (warp direction), andto reach a value greater than that for grey state infabric 1 (warp direction) and fabric 2 (weft direc-tion).

3.1.4 Tensile ResilienceTensile resilience for fabric 1 increases up to

heat-setting, decreases considerably in polyesterand cotton dyeing and again increases, thoughmarginally. in final finishing (Fig. 3).

In fabric 2, tensile resilience in warp directionincreases in scouring and mercerisation, decreasesin heat-setting and again increases in dyeing andfinishing processes. In weft direction, resilience in-

In fabric 1, tensile energy in warp directiondecreases in scouring, increases marginally inmercerisation and the value is retained in heat-setting and polyester dyeing (Fig. 2). Decrease hasbeen observed again in cotton dyeing and finish-ing to the level of scouring. In weft direction, ten-sile energy increases in scouring and mercerisa-tion, but in heat-setting, fabric becomes weak andthe value is retained even after finishing. An ex-actly similar trend is observed for fabric 2 also.Values for grey and finished fabrics .are of thesame order (4.1 & 7.2 gf.cm/cm? for warp andweft directions of fabric 1 and 5.0 & 3.8 gf.cm/ern? for warp and weft directions offabric 2).

0·20 c=JWARP

IZ2ZJWEFT

>t-o O· 4 a j-I-..LL.<L-..L..-J.L.<::L-.J---L~--L--L.<::..L..--L-..1L.~l.--r..L.:JL....I~:::...::L.j

75125 POLYESTER/COTTON 5 UITING

o 0·35ex::ozCizwI!l

0·15Eu

N 0·10Eu

- 0·0501n

0·30

0·25

0·20

67/33 POLYESTER/COTTON ~WITING

0·150·1OU;;;;;ff-'~='~±~~~~-I:-:::~Y~~....L.~U

STAGES OF FINISHINGFINISHED

Fig. 5-Bending rigidity

NATARAJAN etal.: POLYESTER/COTTON SUITING FABRICS 105

0·6.-------,--------------571ll POLYESTER / COTTON SUITING c:::J W"RP

g 0·5 f2Z2lWEFT-E 0'4u

~ 0·3

0·'

o 0.2ziszlJJIDIJ....oIf)

If)lJJ0:lJJ~If)>-I

O~~~~~~~~-L~~L-~~-L~-L~~

0'5

0·'O~~~~~L-~~~~LL-L~~~~~L-~U

0'4

0·3

0·2

STAGES OF FINISHINGPET DYED COTTON DYED FINISHED

Fig. (i-Hysteresis of hen ding

3.2.2 Hysteresis of Bending

Hysteresis of bending shows exactly the sametrend as rigidity of bending (Fig. 6) except thatthe value for finished fabric is smaller than thatfor grey fabric in warp direction (for both fabrics1 and 2) and is greater than that for grey fabric inweft direction (for both fabrics 1 and 2).

3.3 Shear Properties

Results of fabric shear tests are given in Table6. Shear stiffness values are shown in Fig. 7 andthe values of hysteresis of shear at 5° shear angleare shown in Fig. 8.

3.3.1 Shear Stiffness

The shear stiffness (Fig. 7) decreases in scour-ing, increases to a maximum in heat-setting, dec-reases in dyeing and again increases in finishingto reach a level of 2.0 gf.cm/deg in fabric 1 and1.5 gf.cm/deg in fabric 2. These values arc of theorder of grey fabric only.

3.3.2 Hysteresis of Shear

In terms of hysteresis of shear, finishing has af-fected fabrics 1 and 2 in different ways (Fig. 8).For fabric 1, the hysteresis decreases to a low lc-

vel in scouring, reaches a maximum in dyeing andthen decreases in finishing to reach a level of 7.5gf/cm. But, for fabric 2, in dyeing itself, the valuedrops to a low level of 6%.

4 Discussion

Fabric properties are determined by the pro-perties of yarn constituting the fabric and the fa-bric structure. Finishing processes affect the fabricproperties affecting either yarn property or fabricstructure or both.

4.1 Structural Parameters

Fabric structural parameters of fabric 1(spun x spun) and fabric 2 (spun x filament) arcgiven in Table 7.

In fabric 1, there is not much effect on ends/inand picks/in in different finishing stages, whereasthe crimp values change and finally reach 9.37%and 7% respectively in warp and weft directionsrespectively (Fig. 9). The changes in crimp arcmarked in weft direction.

In fabric 2, significant changes have been ob-served in ends/in and warp and weft crimp levels.However, in the final finishing stage, all the par-

0\2-1a"

LJ 1.9Eu.....:1·7en~

If)If) 1'5~~~~~a-~~~L-~~~~~~~~ __~wZ~ 2-5t-If)

0:: 2-0«wIIf)

0::«

~ : I--'---"'-L..I-'---.L...L."'---L--'-"'-"L- II.~--,,:....£....I---.J'---L.<.....<"---..L...-"""""""'-1If) 14.5 7S/H POLYESTER/conON SUITINGW0::Wt-If)>-I

106

2·5

2-3

1-5

Eu--

125

10·5

8'5

6-5

4-5

INDIAN J. FIBRE TEXT. RES., JUNE 1997

57III POL VESTER / COTTONSUITING

DW4RP

~WEFT

HilS POLYESTER / COTTON SUITINc;.

GREY SCOURED Io4ERCERISED HE4T-SET PET DYED COTTON DYED FINISHED

STAGES OF FINISH ING

Fig. 7-Shear stiffness

10

9

57/ll POLYESTER/COTTON SUITING C::J W4RP

fZ2ZI WEFT

8

STAGES OF FINISHING

NATARAJAN et al.: POLYESTER/COTTON SUITING FABRICS 107

Table 7-Fabric structural characteristics

Parameter Fabric I (Spun x Spun) Fabric 2 (Spun x Filament)

FII FI2 FI3 FI4 FI5 FI6 FI7 F21 F22 F23 F24 F25 F26 F27

Count Warp 2130s 2/30s 2/30s 2/30s 2!2Rs 2!2Rs 2/2Rs 2130s 2!30s 2/30s 2/30s 2/30s 2!32s 2!32sWeft 2/30s 2/30s :U30s :U30s 2/2Rs 2!2Rs 2!2Rs 2/30s 2/30s 2!30s 2!30s 2/30s 2/32s 2/32s

Threads/ EPI 64 Mi 61\ 6li 6li 6li 6li liO XO liO 90 92 76 7610.

PPI 4X 4X 46 4li 4X 4X 4X 7H 7li HU liO X6 H2 80

Crimp. 'x, Warp 10.HI 7.0Y 1).33 X.XY 10.17 H.OO 1).33 6.72 4.2R 3.n 7 4.25 S.li3 4.5n n.OOWeft 1).00 X.OX 12.40 I).S() 7.:1.' 10.17 7.00 1).25 13.36 14.17 1).2X R.56 I).IU R.n

Weight. 204.4 IYX.I 202.4 20X.4 20Y 212.2 207.1 213.2 213.5 21K.6 212.2 215.9 220.7 219.2g/rn-

FII & F21-Gray; FI2 & F22-Scoured: FI3 & F23-Mercerised: Fl4 & F24-Hcat-set: FI5 & F25-Polyestcr dyed; FI6 &F26-Col!oll dyed; and FI7 & F27-Finishcd.

67/]) POLYESTER 1

COTTON SUITING12

11

10

9

8-.J 7UJ> 6 ~~~~~~-L~~~~~L-~~~~~~~-X~~UJ 75125 POLYESTER 1 COTTON SUITINC;-l

0.13zcr: , 1u

c::JWARP

f2L::l WEfT

9

7

53UL~4-~~L-~~~~~-L~A-~~~~~~

CREYSCOURED I4ERCERISED HEAT·SET PET DYED COTTON DYED fiNISHED

STAGES OF FINISHING

Fig. Y-Crimp levels

ameters reach their nominal values. Crimp levelsat the finished stage are 6% and H.12°Ic, in warpand weft directions respectively (Fig. 9). In this fa-hric also, ehange in weft crimp is large.

4.2 Yarn Tensile PropertiesAs the yarn tensile properties are expected to

directly contribute to the fahric property, the yarnproperties have been studied more closely.

The tensile strength of warp and weft yarnsmarginally changes between processes. finallyreaching a low level of O.X6 kgf and O.XX kgf rc-spectivcly in fabric I (Fig. 10), whereas in fabric 2(Fig. 10), the yarn tensile strength has not beenaffected in the processes ((U,5 kgf and 0.53 kgffor warp and weft respectively).

Yarn breaking elongation- shows a slightly in-creasing trend in both warp and weft directions

108 INDIAN J. FIBRE TEXT. RES., JUNE 1997

for fabrics I and 2 (Fig. II). However, smaller va-lues do occur in the intermediate processes suchas after polyester dyeing in fabric 1, or after mer-cerisation in fabric 2. In finished fabric 1, clonga-

tion values arc 20.4%, and 24.3% in warp andweft directions respectively, whereas in fabric 2,the values arc 20.4°/c, and 31.1 % in warp and weftdirections respectively.

1·2 o WARPEZ2l WEFT

[J\~I ro~t:)ZW0:f-

if) 0.8W ~--~7S~/~2S~pLOL-Y~E~ST~ELR-/~CO-T-T~ON~5-u-lrLIN-,~LL-2--~~-L~~L-~-L~~

-J 1.0if)ZWf- 0·8z0:«>- 0·6

0'4

57/)) POLYESTER/COTTON SUITING

MERCERISED HEAT-SET PET DYED COTTON DYED fiNISHED

STAGES OF FINISHING

Fig. I(}- Yarn Il'Il,iic ,lrcIlglh

26;---~67~/~))~P~Ol7.Y~ES~T7.E7R~/~CO~T~T~ON~57U--IT7IN--G---------------c==J----W-A-R-P----,

24 ~wEn

22201 8

o0- 16"

z 14of-

«~ 32o-.JW 27

22

17

12~~~~~~~~~L-~L-L-~~~LA~~~SCOURED M[RCERISfO H[AT-S£I PEr DYED COTTON DYED FINISHED

STAGES OF FINISHING

Fig, JJ- Yarn breaking elongation

NATARAJAN et 01.: POLYESTER/COTTON SUITING FABRICS 109

Fahrics I and 2 behave in an opposite way asfar as the initial modulus of yarn is concerned(Fig. 12). In fabric 1, the initial modulus decreasesin the chemical processes, whereas in fabric 2, itshows an increasing trend. In fabric 1, the initialmodulus decreases from 92.5 gf and 84.4 gf inwarp and weft yarns to 59.5 gf and 51 gf respect-ively, whereas in fabric 2, it increases from 93.8gf and 38.5 gf to 135.0 gf and 118.0 gf in warpand weft yarns respectively.

4.3 Yarn Bending PropertiesBending rigidity and hysteresis values of yarns

are given in Tables 8 and 9: It may be observedthat bending rigidity and hysteresis values reach amaximum level after dyeing processes. But, fabricbending rigidity values are minimum after dyeingprocesses. This difference has been reflected inthe bending rigidity index values (Fig. 13), whosemaximum lies in mercerisation/heat-setting, whichmeans that the structure of fabric has significantlyinfluenced the bending rigidity.

10090

80

700'1 60

67133 POLYESTER 1 COTTON SUITING c::::J wup~WEFT

•...~ 50-.J5 40~-LLL~-L~~~~~~~L-L-~~L-L-~L-J-~~

O 75125 POLYESTERICOlT ON SUITING

2: 150-l<l:~z 100

50

SCOURED MER CERISED HEAT'SET PET DYE 0 COTTON DYED FINISHED

STAGES OF FINISHING

Fig. J~-lnitiaJ modulus

Table H- Yarn bending characteristics

Parameter Fabric I (Spun x Spun)

FIJ FJ2 FJ3 FI4 FI5 FI6 FI7

Bending rigidity. gfcm ' Warp 0.0025H (l.0023X (U)()23H (J.()()29R 0.0033R O.0032H (U)0320Weft 0.00303 0.0029R 0.00345 0.00268 0.00290 0.00285 0.00320

Hysteresis of bending Warp O.0()200 (I.()()~OR 0.0020H O.OO2JO 0.00248 0.00268 0.00215moment,gfcm Weft 0.00188 0.00163 0.00235 0.00213 0.00245 0.00245 0.00248

Calculated bending rigidity Warp 0.0(,500 0.06370 (U)6370 0.07980 0.09050 0.08780 0.08570per cm of fabric, gfcm-v cm Weft 0.05730 0.05630 0.06250 0.05060 0.05480 0.05390 0.06050

Bending ridigity index Warp 2.3H('20 J.9<)530 2.2(,050 2.40600 1.44860 1.58540 1.96500Weft 2.91100 1.67140 1.657(,0 3.18380 2.05660 1.85950 2.13720

110 INDIAN J. FmRE TEXT. RES., JUNE 1997

Table 9- Yarn bending characteristics

Parameter Fabric 2 (Spun x Filament)

F21 F22 F23 F24 F25 F26 F27

Bending rigidity/thread, gfcm? Warp 0.00290 0.00278 0.00310 ()'()O463 0.00308 0.00290 0.00225Weft 0.00155 0.00183 0.002211 0.00118 0.00208 0.00150 0.00210

Hysteresis of bending Warp 0.00263 0.00258 0.00203 0.00373 0.00248 0.00213 0.00\90moment/thread, gfcm Weft 0.00085 0.00083 0.00188 0.00110 0.00048 0.00080 0.00015

Calculated bending rigidity Warp 0.09340 0.08760 0.09760 0.16410 0.11160 0.08680 0.06730per ern of fabric, gfcrn-,' ern Weft 0.04760 0.05620 0.07000 0.03720 0.07040 0.04840 0.06610

Bending rigidity index Warp 2.87040 2.89390 3.66090 2.15360 1.79840 2.45510 2.21990Weft 3.83200 2.16010 1.79290 4.42470 1.82100 2.44210 3.47050

32 c:::J WARP

1:22.3 WE F I

,7/)) POLYESTER/conON SUITING

27xW0 2·2z>!o- 1·70c.::>ex: 1·2o 46z0 41zw 3·6CO

31

2·6

2"

1·6GRty SCOUR~D "ERCERISED HEAI'SEI PEl DYED COIION DYED FINISHED

STAGES OF FINISHING

Fig. 13-Bending rigidity index

whereas mercerisation and heat-setting lead to in-crease in these values.

5.3 Changes have also been observed in yarnproperties after each finishing stage. Yarn bendingrigidity and hysteresis values are higher after dye-ing processes compared to those after mercerisa-tion and heat-setting. This shows that changeshave occurred during processing in fabric struc-ture directly affecting the bending characteristicsof fabrics.

5 Conclusions5.1 Changes occur in low-stress tensile, bending

and shear properties to a different level after eachfinishing stage. In general,. scouring and dyeingsoften the fabrics, whereas mercerisation andheat-setting stiffen the fabrics.

5.2 Finished fabrics have smaller bending rigid-ity, bending hysteresis and shear hysteresis valuescompared to grey fabrics. Shear stiffness values offinished fabric are of the same order as of greyfabric. As expected, scouring and dyeing pro-cesses lead to decrease in bending and shear ri-gidity and hysteresis values of both the fabrics

AcknowledgementThe authors sincerely

krishnan, Principal, andthank Prof. P. Radha-Dr K. Jayachandran,

NATARAJAN etal.: POLYESTER/COTTON SUITING FABRICS 111

Head of the Department of Textile Technology,PSG College of Technology, Coimbatore, for pro-viding most of the facilities for carrying out thiswork. They thank the management of Mis Coim-batore Murugan Mills, Coimbatore, Mis Sri Bha-rati Mills, Pondicherry, and to the Director, SIT-RA, for help in the production of samples and incarrying out some of the tests.

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