influence of weave type and weft density **m. e. yazdanshenas … · pilling is a fabric defect...

Lohrasbi F., Ghahi J.l M., Yazdanshenas M. E.; Influence of Weave Type and Weft Density on Worsted Fabric Pilling.FIBRES & TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 (88) pp. 64-69.

64

3)

Influence of Weave Type and Weft Density on Worsted Fabric Pilling

Farshad Lohrasbi, *Jalal Mokhtari Ghahi,

**M. E. Yazdanshenas

Islamic Azad University, 1Arak Branch

Arak, Iran E-mail: [email protected]

*Tehran South Branch, P.O.BOX: 1666976113, No 75, 4th Golestan St.,

Pasdaran Ave, Tehran, Iran

**Yazd Branch,Yazd, Iran

AbstractPilling in textiles has been one of the most significant areas which many researchers, such as Cook, have investigated. In this study, we analysed the pilling of several samples of worsted fabrics: 45% wool/55% polyester with different weft densities and weave types. Rubbing test results were obtained using the Martindale test and by counting pills on the fabric surface assumed. The results show that the more the warp and weft are engaged together in the fabric surface, the fewer pills will form on it; or one may conclude that, in some cases, less pilling forms on the surface when the warp outnumbers the weft (i.e. less engagement between warp and weft), provided that the density of the warp is far larger than that of the weft. But in some fabrics, increasing the weft density will form fewer pills on the surface fabric.

Key words: worsted fabrics, weave type, weft density, pilling.

1. Theestablishmentofalocalisedareaofhighfuzzdensity,

2. Thedevelopmentofalooseentangle-mentwithinthatarea,

3. The tightening of the entanglementintoaroughlysphericalmassoffibre,

4. Thepullingoutoftheanchorfibrestoformadiscrete,mobilepill,

5. Thefractureofcertainfibreduetotherelocationofapill,

6. The fracture of remaining fibre andthelossofthepill[6].

Micro-pilldevelopmentiscoveredbythefirstthreesteps,whichmeansthefirsten-tanglementzone.The development of fuzz into a pill isshowninFigure 1.

Gintis and Mead showed that the in-creasedstrengthandflexlifeofsyntheticfibres reduces the rate of pill wear-off,resulting in higher pill densities and agreatlyincreasedpilllife.Inaddition,thetenacity and rigidity of the fibres affectthe fuzz-development phase 2 - 6 andsubsequent fuzzentanglement in suchawaythatfibreswitharelativelyhighte-

n IntroductionPillingisanimportantproblemnotonlyfortextileandclothesmanufacturersbutalso for users. The effect of the pillingprocess results in a significant decreaseinfabricqualityandanegativeinfluenceonusercomfort[1].

Sirospun yarns are quite sufficient andcomparable to two-plied yarns inmanyoftheperformancecharacteristicsofwo-venworstedfabricswhenoptimumcon-ditions are provided in their productionprocess.Suchfabricsresisttheformationofpillingandabrasionatnearlythesamelevel,andhaveasimilarappearance[2].Apart from the high variety of garmentdesigns, durability is also an importantfactor. Therefore certain specificationslike pilling, which affects durability, isone of the critical problems in the gar-mentindustry.

Pilling is a fabric defect which is ob-servedassmallfibreballsorgroupscon-sistingofintervenedfibresthathavebeenattached to the fabric surfacebyoneormorefibres[3].

Pilling often represents a serious defectina fabricorgarment.Notonlydoes itdetract from the appearance and handleoftheproduct,butitalsohasanacceler-atingeffecton the rateoffibre removalfromtheyarnstructure,hencemateriallyreducingtheservicelife[4].

Throughthepillformationprocess,fibreentanglementmakessomedeformitiesonthefabricsurface[5].

Pill initiationanddevelopmentfollowawell-establishedpatternwithsixstages:

Figure 1. Steps in pill formation [5]; 1) fuzz, 2) loose entanglement, 3) pill (tight entanglement), 4) spiral entanglement.

4)

1) 2)

65FIBRES & TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 (88)

nacityandlowbendingrigiditygeneratehighfuzzdensitieswithhighratesofini-tialpilldevelopment[4].Brand and Bohmfolk assume in theirmodelofpillingthatfuzzfibresdisappearfromthefabricsurfacethroughabrasionorpull-out,whileMotojiandTsujimotoconsider fibre deformation beyond theyield point to be partly responsible forinitial entanglement but do not provideany clear evidence of fibre damage re-motefromthepillsite[4].

Pilling is generatedby repeated frictionforcesactingaccordingtotwocombinedphenomena:theemergingoffibresfromthefabricsurfaceandthepersistenceofneps formed on the same surface. Thefirst phenomenon increases with lowbendingmodulus fibres and a low fric-tion coefficient, while the second oneincreaseswhenfibreshaveahightensilestrengthandhighbendingrecovery.Itisgenerally understood that pilling is par-ticularlyhighinthecaseoffabricscon-taining synthetic fibres, such as polya-mideandpolyester[3].

In cases where the fibre tensile forcesare insufficient to overcome friction-al forces within the yarn, pill growthis restricted, and the roll-up proc-ess leads to pill immobilisation (Fig-ure 2) and an increased pill life due tothe reduced scale of cyclic bendingand torsional strain in the fibres [6].

Hightwistfactorsandtightfabricstruc-tures lead to lowpull-out and restrictedpillgrowthand,forfibreswithhighten-silestrengths,thepillsthatformarelike-lytobecomeimmobileandremainonthefabric surfacewithoutwearing off.The

withthecommonknowledgethatthereismore yarn-to-yarn interlacing in fabricswithsmallerweavefloats[7].

Thepillingofworstedfabricsisaseriousproblemandhasattractedtheattentionofcustomers, manufacturers and research-ers.Inthiswork,theeffectoffabricpa-rameters including the weave type andweft density on the pilling of worstedfabricswasinvestigatedusingthestatis-ticalanalysismethod.

n ExperimentalIn this study, we used worsted45% Wool/55% Polyester fabrics withdifferent warp and weft yarn counts,

meanlengthoffibresextractedfromthefabricsurfaceaffectspillsize[6].

Improved resistance to abrasion due toincreased fabric sett is understandablebecauseasthesettincreases(Figure 3),the fabric becomes more compact andfibre-to-fibre and yarn-to-yarn frictionincreases[7].

Computed changes in fabric propertiesduetochangesintheweavestructureareshowninFigure 4.Intermsofresistancetoabrasion,plainweaveisthebest,and2/1 twill is better than 2/2, 3/1, or 4/1twill.Plainweavefabricshavethehigh-est shear rigidity compared with otherweaves. These trends are in agreement

Roll-out with pull-out

Roll-out without pull-out

Mea

ns lo

ss d

ue to

abr

asio

n, %

Figure 2. Pilling processes [6].

Figure 3. Effect of sett on fabric, assuming a constant yarn linear density of 50 tex, a constant weave crimp of 8%, a changing fabric sett from 29×27 to 10×8, and plain weave fabric [7].

Mean sett, yarns/cm Weave type

Mea

ns lo

ss d

ue to

abr

asio

n, %

Figure 4. Effect of weave structure on fabric properties, assuming the warp and weft yarn linear density are 50 tex, sett 21×19, com-position 22 µm wool, twist 590Z/540S [7].

Table 1. Sample technical data.

Sample no.

Warp and weft count, tex Weave type Weft density, weft/cm Warp density,

warp/cm1 50/2 Twill 1/2 Left to Right 15 16 17.25 18.5 262 50/2 Twill 2/1 Left to Right 15 16 17.25 18.5 26

3 38.4/2 Twill 2/1 Left to Right + Twill 1/2 Left to Right 21 22 23 24 26.25

4 38.4/2 Twill 2/2 Left to Right 21 22 23 24 275 25/2 Satin 4/1↑2 28 29 30 31 40

6 25/2 Twill 1/2 Right to Left + Twill 2/1 Left to Right 25 26 27 28 29 31.5

FIBRES & TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 (88)66

weavetypesandweftdensities,suppliedbytheIranMerinosandMotahhariCom-panies. Detailed specifications of thesamplesarelistedinTable 1.Itmustbenoted that the fibre processes and spin-ningsystemsareexactlythesame.

Each samplewas processedwith 4 dif-ferent weft densities, apart from sam-pleno. 6,whichhadfivedifferentweftdensities. The size of the samples was90 × 150 cm.We prepared 3 pieces ofeachsample,thebackandfront,andthewarpandweftdirectionsweremarked.

Toensuretherandomnessofthetests,wechose samples from different places ofthe fabric surface. Itmustbenoted thatintheMartindaletest, twopiecesofthesamplesmustbeinfullcontactwitheachother.

Testswereperformedinstandardcondi-tions (65%RH and 20 °C). In the pill-ing test,onepieceof thesamplehad tobesetonthelowerheadofthemachine

Table 4. Technical data for wool fibre of a 38.4/2 tex and 25/2 tex yarn count.

Test typeTest result

38.4/2 tex 25/2 texFibre fineness, µm 22 19Weight of sliver, g/m - 20.64Mean length, mm 70 63

Table 5. Technical data for polyester tops of a 38.4/2 tex and 25/2 tex yarn count.

Test typeTest result

38.4/2 tex 25/2 texFibre fineness, µm 2.4 2.4Mean length, mm 91 91

Table 6. Technical data for yarn twist and Twist direction.

Warp and weft count, tex

t.p.m (two-ply) twist direction(two-ply)

t.p.m (one- ply) twist direction(two-ply)

50/2 575 S 662 Z38.4/2 636 S 732 Z25/2 821 S 944 Z

Table 2. Technical data for wool fibre of 50/2 tex yarn count.

Test type Test resultFibre fineness, µm 23.3Weight of sliver, g/m 18.67Mean length, mm 57

Table 3. Technical data for polyester tops of 50/2(tex) yarn count.

Test type Test resultFibre fineness, dtex 3Mean length, mm 66.6

i.e.onthefelt,andthesmallerpiecehadtobeadjustedtothemovingheadofthemachine.

The test cycles were set at 125, 500,750, 1000, 1500 and2000 according toISO12945-2000.Aftereachtestrun,thenumberofpillswascountedhorizontallybyamagnifierunderafluorescentlight.Itmustbenotedthatthelightshouldbesetatanangleof5to15degreestothefabricsurface,andalso thedistancebe-tween the samples and the eyemust bebetween30to50cm.Themeanvalueofthenumberofpillsofeachsamplewasrecorded[8].

Raw Material Specifications The specifications of wool fibres proc-essed to a 50/2 (tex) yarn count by theIranMerinos company are listed inTa-ble 2.Technicaldataofthepolyesterfi-brearealsogiveninTable 3.

Technical data of fibre processed to a38.4/2texand25/2texyarncountbytheMotahharicompanycanalsobeseen inTables 4, 5 and 6.

n Results and discussionTheyarn twistquantitycouldaffect thepillingpropertiesoffabrics.Anincreaseinthetwistfactorresultsinadecreaseinfibremigration,fuzzgenerationandpill-ing.We used the same t.p.m. and twistdirectionfortheweftandwarpyarnsam-ples to eliminate the effect of the twistparameteronthepillingfabrics.

Worsted fabric with 50/2 tex warp and weftAs regards sample 1, (weave: twill 1/2Left toRight) fromFigure 5.a it isob-vious that when the weft density is in-creased first from 15 to 16 and then to18.5,thenumberofpillsdecreasesfrom69to60.Thisapproachiscontinuedbyincreasingtheweftdensity.

Moreover, Figure 5.b illustrates thatby increasing the weft density of thefabric (x), the number of pills (y) de-crease according to the linear equationy=108.415–2.641xandcorrelationco-efficient-0.699.

According to Table 7, the significanceleveloftheexaminationislessthan5%,anditisconcludedthatthereisarealre-lationbetweenpillingandtheweftden-sityoffabric.

As regards sample 2 (weave: Twill 2/1LefttoRight),inFigure 6.awecanseethatthenumberofpillsdecreasesfrom65to51whentheweftdensityisincreasedfirstfrom15to16andthento18.5.

Moreover, inFigure 6.b it is illustratedthat by increasing the weft density ofthefabric(x),thenumberofpills(y)de-creases according to the linear equationy=123.245–3.805xandcorrelationco-efficient-0.758.

According to Table 8, the significanceleveloftheexaminationislessthan5%,anditisconcludedthatthereisarealre-lationbetweenpillingandtheweftden-sityoffabric.

ThecomputedsigfromtheTtestinTa-ble 9isabout0.05,whichmeanssamples1 and 2 are obviously different in theirresponsestothetest.Themeanvalueofpills in sample 2 is lower compared tosample1.

Samples 1 and 2 have nearly the sameweave construction aswell as the sametwistpermeterandtwistdirection:sam-ple1-twill1/2lefttorightandsample2-twill2/1lefttoright).However,thereismorewarpyarnon the fabricsurfaceinsample2,andthedensityofthewarpis farmore than thatof theweft, hence fibres cannot easily come out from thefabricsurfacetoformpills,andthusthenumberofpillsisfewerthaninsample2.


It is obvious fromFigures 5.a and 6.athat whenever the weft density is in-creased, fibres cannot be free from theyarn structure and appear on the fabricsurfacetoformpills.Ontheotherhand,increasing the weft density results infewerpillsonthefabricsurface.

Worsted fabric with 38.4/2 tex warp and weftIn sample 3 (Twill 2/1 Left to Right +Twill 1/2 Left to Right) and sample 4(Twill2/2LefttoRight),wehaddifferentresponses.Tobecertainoftheresult,thetestwasdoneagain,with thesameout-come.AscanbeseeninFigures 7.a and 8.a,(seepage68)theresultsarechangedinadifferentway.

Insample3,accordingtoFigure 7.b,(seepage68)byincreasingtheweftdensityoffabric(x),thenumberofpills(y)arein-creasedaccording to the linearequationy=2.133+0.633xandcorrelationcoef-ficient-0.212.However,thesignificanceleveloftheexaminationismorethan5%inTable 10(seepage68).Itisconcludedthat the number pills are not dependentontheweftdensityoffabric.

Insample4,accordingtoFigure 8.b,(seepage68)by increasing theweftdensityofthefabric(x),thenumberofpills(y)decreaseaccordingtothelinearequationy=41.033-1.003xandcorrelationcoef-ficient-0.241.Althoughthesignificancelevel of the examination is more than5%inTable 11 (seepage68), itcanbeconcludedthatthenumberofpillsisnotdependentontheweftdensityoffabric.

ThecomputedsigfromtheTtestinTa-ble 12 (seepage68) ismore than0.05,hencethereisnoobviousdifferencebe-tween the test results forsamples3and4, According to the mean values, thenumberofpillsinsample3islower.

The factors of warp and weft densitiesare not significant for this sample be-cause the density of the warp is lowerthanthatoftheweftinsamples3and4.However,intheweavesTwill2/1LefttoRight+Twill1/2LefttoRightandTwill2/2LefttoRight,morewarpandweftareinterlaced togetheron the fabricsurfacebecause fibres cannot easily come outfromthefabricsurfacewithweaveTwill2/1LefttoRight+Twill1/2LefttoRighttoformpills.Therefore, therearefewerpillsinsample3.

Figure 5. Effect of weft density on pill formation (a) and curve estimation of regression (b) for sample 1 - Twill 1/2 Left to Right.

Table 7. Analysis of regression and parameter estimates for sample 1 - Twill 1/2 Left to Right; Dependent variable: average number of pills, independent variable: weft density.

EquationModel summary Parameter estimates

R. square F df1 df2 Sig. constant b1

Linear 0.488 9.528 1 10 0.012 108.415 -2.641

a) b)





Linear 0.574 13.473 1 10 0.004 123.245 -3.805

a) b)

Table 9. T test for sample 1 (Twill 1/2 Left to Right) and sample 2 (Twill 2/1 Left to Right).

Group statistics

(Twill 1/2 Left to Right) = 0 &(Twill 2/1 Left to Right) = 1 N Mean Std.

deviationStd. error

mean

Pills (Twill 1/2 Left to Right) 0.00(Twill 2/1 Left to Right) 1.00

1212

64.341759.7500

5.195016.90053

1.499671.99201

Independent Samples Test

Equal variance

Levene’s test for equality of

variance

t-test for equality of means

t df Sig. (2-tailed)

mean difference

std. error difference

95% confidence interval of the

difference

F Sig. lower upper

Pills (Twill 1/2 Left to Right) & (Twill 2/1 Left to Right)

assumed 0.453 0.5081.842

22.0 0.0794.5917 2.4934

-0.5794 9.7627

not assumed 20.4 0.080 -0.6024 9.7857

FIBRES & TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 (88)68

As mentioned before, Figures 7.a and 8.ahavedifferentgraphs,presentingtherelationbetweenweftdensityandpilling.

Worsted fabric with 25/2 tex warp and weftAsregardssample5,weaveSatin4/1↑2,itcanbeseeninfigure13thatthenumberofpillsdecreasesfrom47to33whentheweftdensityisincreasedfirstfrom28to29andthento31.

For sample 5, according toFigure 9.b,by increasing the weft density of thefabric (x), the number of pills (y) de-creases according to equation lineary=162.573–4.22xandcorrelationcoef-ficient-0.806.

According toTable 13, the significanceleveloftheexaminationislessthan5%,anditisconcludedthatthereisarealre-lationbetweenpillingandtheweftden-sityoffabric.

For sample 6, with weave: Twill 1/2Right to Left+ Twill 2/1 Left to Right,thenumberofpillsdecreaseswithanin-crease inweftdensity,and then there isanincreaseinthenumberofpills,whichiscontrarytoourtheory.Tobecertainofthe result, the last testwas done again,andtheoutcomewasthesame.Itispos-siblethatthedirectionofSandZintheweaveconstructioncanhaveaninfluenceontheresults.

As regards sample 6, according toFig-ure 10.b,byincreasingtheweftdensityofthefabric(x),thenumberofpills(y)increasesaccordingtothelinearequationy=-32.517+3.957xandcorrelationco-efficient-0.531.

According toTable 14, the significanceleveloftheexaminationislessthan5%,anditisconcludedthatthereisarealre-lationbetweenpillingandtheweftden-sityoffabric.

InTable 15,thecomputedsigfromtheTtestislessthan0.05,hencethedifferencebetweentheresultsforsamples5and6,withrespecttotheincreaseinweftden-sity,isobviouslyremarkable.

Because thewarpandweft in sample6isinterlacedmorethaninsample5,theremustbefewerpillsonthesurfaceofsam-ple6;however,thedensityofthewarpisfarmorethanthatoftheweftinsample5,hencefibrescannoteasilycomeoutfromthefabricsurfacetoformpills.

Figure 7. Effect of weft density on pill formation (a) and curve estimation of regression (b) for sample 3 - Twill 2/1 Left to Right + Twill 1/2 Left to Right.

Table 10. Analysis of regression and parameter estimates for sample 3 - Twill 2/1 Left to Right + Twill 1/2 Left to Right; Dependent variable: average number of pills, independent variable: weft density.



Linear 0.045 0.473 1 10 0.507 2.133 0.633

a) b)





Linear 0.058 0.614 1 10 0.451 41.033 -1.003

a) b)

Table 12. T test for sample 3 (Twill 2/1 Left to Right + Twill 1/2 Left to Right) and sample 4 (Twill 2/2 Left to Right).

Group statistics

(Twill 2/1 Left to Right + Twill 1/2 Left to Right) = 0 &(Twill 2/2 Left to Right) = 1 N Mean Std.

deviationStd. error

mean

Pills (Twill 2/1 Left to Right + Twill 1/2 Left to Right) 0.00(Twill 2/2 Left to Right) 1.00

1212

16.383318.4583

3.48084.8710

1.00481.4061


Equal variance


variance



mean difference



difference

F Sig. lower upper

Pills (Twill 2/1 Left to Right + Twill 1/2 Left to Right) & (Twill 2/2 Left to Right)

assumed 0.270 0.608

-1.201

22.0 0.243

-2.0750 1.7282

-5.659 1.5092

not assumed 19.9 0.244 -5.681 1.5311


Received 10.03.2010 Reviewed 15.11.2010

Furthermore the density of the warp isless than that of the weft in sample 6,thereforefibrescaneasilycomeoutfromthefabricsurfacetoformpills,hencewehavefewerpillsinsample5comparedtosample6.

Figure 9.ashowsthatwhenevertheweftdensity is increased, fibres cannot eas-ily come out from the fabric surface toformpills.Ontheotherhand,increasingtheweftdensityresultsinfewerpillsonthefabricsurface.ButinFigure 10.awehavedifferentresults.

n Conclusion1. Thedensityofwarpandweftyarnsaf-

fectsthepillingofworstedfabrics.2. Theweavetypeandinterlacingwarp

yarn with weft yarn also influencethe pilling of worsted fabrics. How-ever,whenthedensityofthewarpisfarmore than that of theweft,warpdensityhasmoreofaneffectthantheweave typeon thepillingofworstedfabrics.

3. Inweaves, whenever themorewarpand weft are interlaced together inthe fabric surface, the change in thenumberofpillsislesswithincreasingweftdensity.

4. The statistical investigations pre-sented herein, based on regressionequations and graphs, illustrate thatthenumberofpillsdecreasesinmoresamples(1,2,4and5)whentheweftdensityisincreased.

References1. Jasinka I.;Fibres&Textiles inEastern

Europe,Vol. 17,No. 2 (73), 2009, pp.55-58.

2. KalaogluF.,OnderE.;“Pillingandabra-sion performance of worsted fabricsfromdifferentyarns”International.Text.Bulletin.,April2003.

3. Lucas J.M.,MiguelR.A. L.,CarvalhoM.D.L.,ManichA.M.; “FabricDesignConsidering theOptimisation ofPillingFormation”MagicWorldofTEXT.,Octo-ber2004.

4. CookeW.D.;J.Text.Inst.,No.1,1982.5. GoktepeO.;Textile.Res. J., 2002(72),

pp.625-630.6. CookeW.D.;J.Text.Inst.,No.3,1983.7. FanJ.,HunterL.;Textile.Res.J.,Octo-

ber,1998(68),pp:763-771.8. ISO12945“PartII:ModifiedMartindale

method”4130-2,1stRevision.Mar,2002.

Figure 9. Effect of weft density on pill formation (a) and curve estimation of regression (b) for sample 5 - Satin 4/1↑2.

Table 13. Analysis of regression and parameter estimates for sample 5 - Satin 4/1↑2 to Right; Dependent variable: average number of pills, independent variable: weft density.



Linear 0.651 18.650 1 10 0.002 162.573 -4.220

a) b)

Figure 10. Effect of weft density on pill formation (a) and curve estimation of regression (b) for sample 6 - Twill 1/2 Right to Left + Twill 2/1 Left to Right.

Table 14. Analysis of regression and parameter estimates for sample 6 - Twill 1/2 Right to Left + Twill 2/1 Left to Right; Dependent variable: average number of pills, independent variable: weft density.



Linear 0.282 5.108 1 13 0.042 -32.517 3.957

a) b)

Table 15. T test for sample 5 (Satin 4/1↑2) and sample 6 (Twill 1/2 Right to Left + Twill 2/1 Left to Right).

Group statistics

(Satin 4/1↑2) = 0 &(Twill 2/1 Left to Right) = 1 N Mean Std.

deviationStd. error

mean

Pills (Satin 4/1↑2) 0.00(Twill 1/2 Right to Left + Twill 2/1 Left to Right) 1.00

1212

38.083375.1167

6.107812.0541

1.76321.4797


Equal variance


variance



mean difference



difference

F Sig. lower upper

Pills (Satin 4/1↑2) & (Twill 1/2 Right to Left + Twill 2/1 Left to Right)

assumed 6.901 0.015-9.493

22.00.000 -37.033 3.9009

-45.12 -28.94

not assumed 16.30 -45.29 -28.78

influence of weave type and weft density **m. e. yazdanshenas … · pilling is a fabric defect...

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