Effect of Weft Rewinding Tension on Fabric Properties

Indian Journal of Textile Research

Vol. 10, March 1985, Pp. 26-27

I C SHARMA, S K BHARDWAJ, NARENDER KUMAR GUPTA & AYUSH SHARMA

The Technological Institute of Textiles, Bhiwani 125022

Received II July 1984; accepted 27 August 1984

/The effect of different weft rewindin~ tensions of texturized polyester filament yarns of 150 and 150/2 deniers on fabricproperties, such as tearing strength, breaking strength and dye uptake, has been studied. At both deniers there was nosignificant effect on the tearing strength and tensile strength in weft direction. The elongation at break decreased with increasein tension in both the cases. The dye uptake, measured in terms of optical density, decreased initially with increase in tensionbut with further increase in tension, increased in both the cases.

Results and DiscussionTensile strength and elongation- Data on the tensile

strength (Table 1)and elongation (Figs I and 2) of thefabric show that the increase in tension for a particulardenier does not cause any effect on the strength whilethe fabric is tested in weft direction but the elongationat break decreases with increase in tension. The reasonfor insignificant changes in tensile strength is that thetension increase is not sufficient to cause any change inthe structure of yarn or to damage the filament whichcan affect the strength. The elongation decreases atbreak because of increase in tension. This is becauseevery yarn has some original elongation at break, andincrease in tension causes some elongation owing towhich the residual elongation, observed during testing,decreases. Further, the tension may not be sufficient tocross the critical level and thus is not able to changethe potential energy and hence latent crimp.

Tearing strength- The data given in Table 1 showthat there is no significant change in tearing strengthwith increase in tension in both the cases. This can beexplained as due to the same factors considered earlierin the case of tensile strength.

Dye uptake- Figs 1 and 2 show that the amount ofdye uptake decreases while the tension in the yarn

conforming to the British Standard were used todetermine fabric characteristics. The fabric strengthwas tested on a German tensile tester to determine thebreaking load as well as the extension at break. Todetermine the tearing strength, single rip tear testsamples were prepared and tested on the samemachine. The tests for the tensile strength were donewith ravelled strip test, by taking 7 in. gauge length.Five readings for each tension level were taken. Thesamples for the dye uptake tests were taken randomlyfrom the fabric sample and the change in uptake wasnoted for polyester weft only. Tests were performed ona photocolorimeter (Toshniwal) by using m-cresol assolvent for the polyester.

Materials and MethodsTextured polyester filament yarn of two different

deniers (I50 and 150/2) were used to prepare thesample. With each denier, six tension levels wereselected to prepare the pirns for making the fabricsample. The pirns were prepared on a Laxmi Schwieter

pirn finder and run on a shirting fabric. Theparticulars of the fabric are:

Ends per inch x picks per inch -46 x 72 for 150denier; and 46 x 44 for 150/2 denier.

Warp count - 2/34s (polyester-viscose blendproportion, 67:33).

The fabric was processed with a few changes in thenormal procedure. It was heat-set, and dyed at 1300eon a beam dyeing machine. The material was not takenon jiggers for cellulosic component, so only thepolyester component of the fabric was dyed. Thecomponents of disperse dyes used were Disperse BlueBT (0.175%) and Disperse Red B2B(0.005%).

Before testing the sampleSiin the weft direction, allthe samples were conditioned under standardatmosphere for 48 hr. Standard test methods

Yarn is tensioned by applying load on the yarn in thelongitudinal direction, and when the tensionedmultifilaments are heat-set, there is permanentdeformation in the structure of the filament. Heat­setting the polyester filament at different temperaturesbut at constant tension causes structural changes in thefilament!, which are similar to those caused by thesetting of filament at constant temperature but atdifferent tensions; heat-setting at different tempera­tures also generates some tension in the filament. Heat­setting of filament at different tensions causes changesin the physical structure of the filament which affectthe dye uptake of the filament. In the present study, theeffect of six different weft rewinding tensions oftexturized polyester filament yarns of 150 and 150/2denier~ on fabric properties, such as tearing strength,breaking strength and dye uptake, has been studied.

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SHARMA et al.: EFFECT OF WEFT REWINDING TENSION ON FABRIC PROPERTIES

24

150/2 DENIER YARN

0·6

References

I Warwicker J 0, J Soc Dyers Colour, 88(4) (1972) 142.2 Achwal W B & Hublikar S N, Man-made textiles in lrUJia, 22

(1979) 435.3 The dyeing of synthetic polymer and acetate fibre, edited by D M

Nunn (Dyers Company Publications Trust, England) 1979,152-155.

4 Shenai V A, Chemistry of dyes and principles of dyeing (SevakPublications. Bombay) 1973, 328-331.

AcknowledgementThe authors express their thanks to Prof. R C D

Kaushik, Director, TIT, Bhiwani, for permission topublish this paper. They are also thankful to Prof. S DDeshpande for his cooperation and help.

10 29 30 40 50 '60'ENSIGN, 9

Fig. 2-Ellect of tension on elongation (0-0-0) and dyeuptake (0-0-0)

Conclusions

(1) There is no significant difference in the breakingstrength of fabrics with change of tension in weft-wisedirection for both the deniers (150 and 150/2).

(2) The elongation at break decreases in weft-wisedirection with increase in tension level f<,>rboth thedeniers.

(3) There is no significant difference in weft-wisetearing strength of fabric while tension level changeswithin a particular denier. But with increase in denier,the tearing strength increases.

(4) The dye uptake of the weft yam decreasesinitially up to a certain level of increase in weft tensionbut later, it increases with further increase in tension.The amount of tension at which dye uptake curvereverses differs for the two deniers, i.e. 25 g for 150denier and 40 g for 150/2 denier.

and dye uptake is very similar to that of the curvesobtained in the case of the polyester ruament yamheat-set at different temperatures and the correspond­ing dye uptake of the filamene -4. Here also, similarchanges appear in the filament structure whichultimately cause changes in dye uptake. In this case,the calibration curing was not done, because it wasnot found to be necessary, as we were interested onlyin the comparison of the samples .

16

za15 ~ozo

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W14

13

....J«!:2 03b:oLJw:.::«~[L::J

~ 02o

Sl. Tension Fabric with weft ofNo.

gISO denier

150/2 denier---Tensile TearingTensileTearingstrength

strengthstrengthstrengthkg

kgkgkgI

1076.72.6072.85.842

I:>76.52.6473.75.803

2076.12.4672.55.804

2576.52.8472.85.805

3576.32.6472.75.766

4076.22.6573.05.68

0'41 150

DENIER YARN

Table I-Effect of Weft RewindingTensionof Texturized.PolyesterFilamentYarns on Tearingand TensileStrengths

of Fabrics

10 20 30 40

TENSION,g

Fig. I-Effect of tension on elongation (0-0-0) and dyeuptake (0-0-0)

increases up to a particular level - 25 g for ISOdenierand up to 40 g for 150/2denier. Later, in both the cases,the dye uptake starts increasing with increase intension. This trend can be explained as follows: Thetension required to disrupt the large crystallineaggregates is greater than that required for smallerones; and as the fibres are stretched on a hot-airstenter, the chain molecules get more and moreoriented, i.e. they get stretched into a more orderlyarray, thus leading to a decrease in the dye uptake.Moreover, reduction in bulkiness. with increase intension also causes some reduction in dye uptake up toa tension level of 40 g and afterwards increase in dyeuptake is probably due to the disordering of chains.This is because, with further increase in tension, the

. above-mentioned mechanism plausibly fails and thechain molecules become more and more disordered,leading to increase in the dye uptake. The shape ofcurves showing the relationship between tension level

27