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Studies on Abrasion Resistance of Silk Fabrics

Studies on Abrasion Resistance of Silk Fabrics

Indi an Journal of Fibre & Research Vol. 29, March 2004, pp.69-73

Studies on abrasion resistance of fabrics

B V Vaslimathi . T I [ Somashckar", S L Chil akwad & G Shrikanth Central Sil k Technological Research Institute, BTM Layout, Madi vala, Bangalore 560068, lndia

Receil'ed 16 Jllly 2002; Revised received 9 December 2002; accepted 18 Decell/ber 2002

Around 100 different sampl es of commercially popul ar sil k fabrics were coll ected and tested for fabric constructi onal particulars and two functional properties, viz abrasion resistance and bursting strength . The silk fabrics were tested for abrasion resistance on both Taber type and Martindale testers and the end point of the test was determined as per th e pin­ hole and wei ght loss methods. Abrasion resistance, expressed in terms of number of cycles to form a pin-hole, showed better consistency in terms of vari ous inter-relati onships. The interdependence of factors influencing th e abrasion resistance wi th other functi onal properties have also been deduced. Keywords: Abrasion resistance, Martindale tester, Silk fabric, Taber tester IPC Code: lnt. 0 7 D06H 3/00

1 Introduction Some abrasion effects are immediately recognizabl e. One of the most important physical properties of a Where the rubbing is general over a large area, there textile fibre in relation to durability is its ability to may be a thinning of cloth and a loss of strength , withstand abrasion. Fibres with poor abrasion leading eventually to bursting or tearing. If the wear is resistance break and splinter, leading to the formation concentrated, the first effect to be noticed is likely to be of holes in the fabric) . Abrasion of fabrics may take a hole. If the cloth is square in construction, i.e. having place in normal usage when they are flat, folded or equal numbers of similar in both the warp and curved such that the fibres are subjected to three types weft, it is possible that the hole will be formed by the of abrasion, namely fl at, flexed and edge. Prediction destruction of both sets of threads in the same area. ]f, of performance in relation to abrasion is considered to however, one set of threads is predominant on the be difficult as many factors influence abrasion) . Some surface of the cloth, as in the case of dupion sil k fibres have better abrasion resistance than do others. fabrics, these threads are abraded preferenti ally and the construction is also an · influencing factor. hole will be seen to be crossed by a ladder of the Loosely twisted yarns abrade more easily than do opposing threads. Such a hole may be the starting point tightly twisted yarns. In the loosely twisted yarns, the of a tear if the cloth is sufficiently stressed in that area:! . 4 7 individual fibres are more likely to be subjected to The reports - on the abrasion resistance of a wide being pulled out from the body of the yarn onto the range of fabrics do not include silk. However, si lk is 2 surface of fabric • rated as one with poor abrasion resistance. It is found In construction, the aspect of crimp that the problems associated with the characterizati on di stribution seems to be particularly important. The of in respect of abrasion resistance are serious crown, a part of the yarn that protrudes above the and by no means solvedI.2. surface of the fabric, is subjected to the pressure and The imitative test for wear :-esistance is branded as a surface or edge abrasion. If there are more crowns of 8 snare and a delusion . It is not required that service li fe the same height in a given area of cloth, the wear will be forecast in same unit of time, but a relati ve be distributed over the surface of the fabric more comparison of one fabric with another would be more evenly 3 . Fabrics made from uneven loosely twisted 9 meaningful . slubbed yarns with higher unevenly spaced crowns have poor abrasion resistance ). In the present work, around 100 different samples of commercially popular silk fabrics were collected and two tested for fabric constructional particulars and two aTo whom all the correspondence should be addressed. Phone: 26685238 ; Fax: +91-80- 26680435; functional properties, viz abrasion resistance and E-mail: cstri @vsnl. bursting strength. The silk fabrics were tested for 70 INDI AN 1. FIBRE TEXT. RES., MARC H 2004 abrasion resistance on both Taber type and Martindale abrasive / wear action results when a pair of abrasive testers wheels is rotated in opposite directions by a turn table on which the specimen material is mounted. 2 Materials and Methods An exclusive feature of the Taber abrasers is a Around 100 samples of vari ous types of patented "X" pattern of abrasion, produced by a rotary commercially popu lar silk fabrics were coll ected and rub-wear action of the wheels. The wear pattern tested for fabric constructional particulars and two of formed is that of two intersectin g areas or a sli ghtly th e functional properties, viz abrasion resistance 10 and curved configuration fr m th e outside to bursting strength. The range of fabric particul ars of the centre and from th e centre to the outsid e of th e th ese samples are given in Table I. Crimp ratio (warp specimen. An area of 30 cm2 was subj ected to test and crimp/we ft crimp) has been used instead of absolute a complete circle on the material surface was abraded valu es of warp crimp and weft crimp since the relative at all angles of grain or weave. There was provision maonitude is what is known to influence th e abrasion "" for vacuum pi ck-up for removing abraded parti cles properties of any fa bri cs. from th e urface of the fabri c. The two philosophies, one of duplicating actual The test results were later analyzed statistically to conditions of wear and th e other of selecting the most study th e inter-relationships and to draw inferences. important causes of wear and correlating them wi th The analyses were carri ed out variety wise and th e service tests, have led to the development of more poo led data across all the vari eti es of si Ik fabrics have . I ' II th an 50 abrasion and wear testing mac ll11es . been referred to as 'Overall '. The following In th e present study ., th e si Ik fabrics were tested for observations were made: abrasion resistance on two types of abrasion testers, (i) Correlation of the abrasion test results of viz Taber type and Marti ndale testers. The end point Martindale and Taber type testers was studi ed. of the test was determined as per th e pin -hole method (ii ) Correlati on between the abrasion test results and weight loss meth od. In th e pin-hole meth od, th e was also determined on the basis of weight loss and fabric was abraded till a hole was fo rmed on its pin-hole methods. surface, while in the weight loss method, th e fabric (iii) The abrasion test results were correlated with was abraded for 50 cycles. The initial weight and th e 2 different fabric parameters, viz wei ght/m , thickness, final wei oht were determined for calcul ating the per "" cover factor, etc. cent weight loss. (iv ) 't' tests were carried out to establish the 2.1 Marlindale Tesler sionificance of di ffe rences in the abrasion resistance The tester is designed to ensure that the speci men of"" the most common varieties of silk fabrics. under test is subj ected to rubbing and fl exing from all 3 Results and Discussion directions. The pattern traced by th e abradin g heads is The abrasion resistance values of various types of the well-known ' Lissajous' figure. An area of 100 silk fabrics tested are given in Table 2. cm2 was subjected to abrasion in all the directions. It was used to compare th e resistance to abrasion of 3.1 Influence of Method of Test different types of cloths. Abrasion resistance, expressed in terms of number of cycles to form a pin ho le, shows better consistency 2.2 Taber Type Tesler in terms of various inter-relationships, while the Material s to be tes ed are subjected to wear action weioht loss method does not show any trend. The of two abrasive wheels at a known pressure. The probable"" reasons for the lack of correlation in the case

Table I- Range of fabri c parameters for different silk fab ri cs

Fabri c Endslinch Picks/i nch C rimp ratio Warp deni er Weft denier We ight, g/m2 Cover fac tor T hi cknes , mill Soft silk 100- 129 92 - 127 1.2 - 8.1 18.3 - 38.5 18.2 - 56.4 18.2 - 56.4 11.2 - 18.9 0. 12 - 0.15 120- 248 90 - 115 4.0 - 14.6 29.8 - 36.4 65. 1- 100.9 51.5- 77.9 17 .5 - 23.6 0. 13-0.17 Dupi on 92 - 240 S9 - 95 3.5 - 16.5 23.5 - 44.6 155 .2 -4 11.5 75.5-134.0 16.6 - 24.4 0.15 - 0.36 138 - 223 64 - 11 0 0.1 - 0.6 17. 6 - 22.3 18.6 - 46. 1 20.0 - 34.8 12.0 - 17.2 0. 12 - 0.18 Georgette 102 - !1 2 82 - 95 0.5 - 1.6 18.9 - 43.8 20.5 - 37.6 17.0 - 36.2 10.7 - 14.6 0.12 - 0.16 Crepe 108 - 141 69 - 129 0.4 - 1.3 34.6 - 87.9 33.6 - 81.0 32.0 - 65.9 13.9 - 19.5 0.13 - 0.20 SateenfTwill 120 334 103 155 0.9 1.3 35.3 - 52.8 36.1 - 62.9 5 1.6 - 92.5 17.6 - 27.7 0.12 - 0.25 VASUMATHI el al.: ABRAS ION RES ISTANCE OF SILK FA BRICS 71

Table 2-Abrasion resistance of vari ous sil k fabrics resistance expressed in terms of number of cycles to

Num ber of cycles to Weight loss (%) aft er 50 form a pin hole (Table 3). It is also observed th at the Fabric from a Ein hole c~cles weight loss on the Taber tester is much more th an that Martindale Taber Martindale Taber on the Martindale tester. One of the reasons for thi s is Soft sil k 52.7" 38.3" 0.56 2.65 the presence of vacuum sucti on arrangement in Taber. b Du pion 29.8 2 1.1 h 0.57 3.96 The abraded fibre particles are duly sucked away Taffeta 63.3c 56.8" 0.28 0.93 from the fabric, while thi s has to be done manu all y in h b Crepe 27.6 18.8 0.96 1.60 the case of Martindale tester at regul ar intervals. Georgette 9.0d 7.0d 0.2 1 2.83 Chi ffo n II.Od 10.2d 2.64 1.26 3.3 Influence of Variety of Fabric Twi II/ 85.0e 77.0e 0.60 1. 60 Overall 50.6 33.9 0.63 2.32 Chiffon and georgette fabrics show the least resistance to abrasion followed by the crepe fa brics. J.b.c.d & e indicate signi fica nt di fference at 5% Chi ffon and georgette have hi gh twisted yarn s in both Table 3-Correlatio n between Martindale cycles and Taber cycles , while crepe has high twisted yarn on ly Fabric Correlati on coefficient (r ) in the weft. It is observed that the hi gh twi st sti ffens the Soft sil k 0.82" yam to a point where very little contact is made Dupi on 0.92" between yarn and abrasive. This, in turn, results in hi gh Taffeta 0.92 " b locali sed abras ive pressure and earl y breakdown of Crepe 0.47 4 Overall 0.79" yarn structure . It has been shown that an optimum

" Significant at 1%: b Signi fica nt at 5%. twist is recorded beyond which the increase in number 9 of twists results in lower abrasion resistance . of weight loss were identified to be: (i) the size of the The plain fabrics exhibit lesser abrasion resistance sample prepared for the test is much larger th an the than taffeta, while the abrasion resistance of dupion size of the specimen actuall y abraded, resulting in the silk fabrics is lower than that of pl ain fa brics. The di fference in weights, especial ly in the case of Taber reason for the low abras ion resistance of dupion fa brics tester, (ii ) there is no sucti on device in Martindale could be attributed to the greater imbalance in the tester to suck the abraded fibre particles from the construction of fabric owing to the huge difference in surface, thereby all owing these particles to clog onto the deni er of dupion yarn used as weft and reeled sil k the surface of either the abrader or the abradant, and yarn used as warp. This also results in greater (i ii ) since silk has comparati vely low abras ion di fference between warp crimp and weft crimp. resistance, it continues to abrade the surface fo r a Increased fabric thickness and larger yarn di ameter are defin ite number of cycles (say 50) even after a hole is generally related and provide marked improvement in 4 fo rmed and destructs the fabri c to a greater extent, abrasion resistance of textile structures . However, the sometimes di sintegrating the fabric structure. This largest di ameter of the abrasion bearing yarns mu st be leads to the generati on of a large quantity of lint accompani ed by yarn uniformity if increased wear li fe whi ch gets embedded onto the fabric surface. is desired. This is not so in the case of clupion sil k Therefore, it was decided to use the abrasion fabrics. It is reported that the non-uniform heavy yarn s resistance results obtained from the pin-hole method actually cause fabric degradati on because of the high for further analysis. pressure concentration at their crowns. 3.2 Influence of Type of Tester The better abrasion resistance of taffeta can be Table 2 shows that the abrasion resistance attributed to th e hi gher warp densit y. It has been measured on Taber tester in terms of cycles to form a shown th at when all other factors are taken constant, pin hole is lower th an the corresponding results the abrasion resistance of warp flu sh fabrics is obtained on Martindale tester in all the varieties. The improved by increasing the number of warp crowns 4 reason could be that the two abraders act on the fabric per square inch of the fabric . It is also stated that the surface simultaneously in case of both Taber and warp texture should not be increased to the point of Martindale testers and the fibres separated from the jamming the warp threads and reducing the fle xibility fabric surface due to abrasion gets clogged onto its of fabric structure. surface, thereby delaying th e end point. and sateen silk fabrics show the hi ghest There exi sts significant correlation between abrasion resistance. This reiterates the fact th at weave Martindale and Taber in th e case of abrasion has an influence on th e abrasion resistance of fabrics. 72 INDlAN J. FIBRE TEXT. RES., MARCH 2004

Table 4-Correlation between abrasion cycles and fabric parameters Parameter Soft Silk Dupion Taffeta Crepe Overall Martindale Taber Martindale Taber Martindale Taber Martindale Taber Martindale Taber b b c b b Weight. g/m2 0.49" 0.60 " 0.49" 0.51 " O.77 0.S3 0.3S 0.S3 0.32h 0.33 Thi ckness, mm 0.25c 0.29 c 0.09 c O.IO c 0.65" 0.74b O.IS c 0.50 " 0.25 " 0.21 " Crimp ratio 0.13c 0.14c -0.3 1" -0.24 c 0.06 c 0.07 c 0.25 c O.77b -0. 19 c -0.1 3 c b b b c b Cover fac tor 0.6 1" 0.62b 0.75 0.76 0.S3 0.94b 0.37 0.S5 0.29" 0.35" b b c c End s/inch 0.52c 0. 47 c 0.S3 0.S2b 0.S5 0.94b 0.61 " 0.50 0.3 1h 0.20 c c c b b Warp deni er OAS 0.6 1h 0.09 0.13 C 0.09 O. OJ C 0.69" 0.79 OAS 0.61 " b b c b Bursting strength , kg/cm2 0. 14c 0.4S" 0.34" OAI b O.77 0.74 0.07 0.74 0.26" 0.52h "Significant at 5%; bS ignificanl at 1% ; cNot Signifi cant

4 This is in agreement with the earli er observations . In fabric degradation because of the high pressure 4 fabrics with floats, the yarn s and fibres are more free concentration at their crowns . to move and are less consistently exposed to There is a significant correlation between cover abradants. For this reason, twill and sateen fabrics factor, weight and abrasion resistance in all the cases. may show better abrasion resistance. However, the The dependence of fabric abrasion resistance on the longer floats do have adverse effect on the abrasion cover of the fabric and its weight is establi shed beyond resistance of fabrics as already observed in the case of doubt in all the sorts tested. some jacquard designs 1.3. Incidentally, there has been a significant relationship between bursting strength and abrasion resistance in 3.4 Influence of Fabric Parameters Con'elation studies between abrasion resistance and almost all the valieties tested (Table 4). Bursti ng fabric parameters were carried out for the four varieties strength is the composite strength of both warp ancl of ilk fabrics, viz pl ain , taffeta, dupion and crepe , we ft and it indicates their ability to withstand th e multi­ which showed moderate abrasion resistance. The directional loading. Abrasion is recognized as a seri es vari eties at the two extremes, viz. chi ffon/georgette of repeated application of stress and therefore a with very low abrasion resistance and sateen/twill with capacity to absorb the stress is required on the entire very hi gh abrasion resistance, were excluded. The fabric structure including the fibres. Thi s similarity abrasion resistance of these fo ur vari eti es of fabrics could be the contributing factor for the interdependence shows significant dependence on weight, thickness, of these two factors across all the varieties of silk cover factor and bursting strength of the fabric fabrics tested. Multiple regression analysis was carri ed out to (Table 4). However, there are some exceptions. estimate the strength of relationship between the Wherever the thickness of the fabric is primarily due abrasion cycles and all the fabric parameters. The to the coarseness of either the warp or the weft multiple regression equations along with the R2 values resulting in an imbalance of the structure, a higher are given in Table 5. The explanation for the significant fabric thickness is not contributing to abrasion relationships observed in the analysis can very well be resistance as can be observed in the case of dupion explained in the context of the findings of the earlier fabrics. Here, the increase in thickness is largely due to 4 studies . The variety-wise explanations are as given the greater imbalance in the crimp of warp and weft under: because of the coarser weft used and a higher warp density. The abrasion resistance in this case is not Soft Silk Fabrics-The abrasion resistance of soft showing any improvement with the increase in fabric silk fabric is observed to be a function of its cover thickness while in the case of taffeta, where the factor. Soft silk fabric being almost a square fabric, it is increase in thickness is due to a closer construction quite understandable that its cover factor significantly (i ncreased sett in the fabric), the abrasion resistance is explains the abrasion resistance with equal role of warp positi vely correlated with thickness. and weft. The abrasion resistance is related to the thickness or Dupion Silk Fabrics-Here, endslinch, crimp ratio di ameter of that part of the textile structure which is and cover factor explain the abrasion resistance of the exposed at the rubbing surface. For plain fabrics with fabric. Dupion fabrics are weft predominant. The warp hi gh warp crimp and low weft crimp, the rate of denier is much fin er than the weft denier and the warp 4 damage is hi gher. Non-uniform yarns actuall y cause crimp is also much hi gher. It is observed that the VAS UMATH I et al.: ABRASIO N RESISTANCE OF SILK FABRICS 73

Table 5 - Multiple regression of Jbrasion cycles with fabric parameters Fabric Tester Constant Endslinch Warp deni er C ri mp ratio Cover factor Thickn ess R2 Soft Sil k MartindJle -69.2 + 7.2 0.3 1" Taber - 18.1 + 3.3 0. 33" Dupion MartindJle -9:l.4 0.35 1 -2.232 + 5.05 0.65 ~ Taber -9.28 0.255 0. 66 ~ Taffew Martindale 45.99 0.54 0.69 " TJber -32.81 0.442 0.87 h Crepe Martindale - 1.888 0.60'+ 0.42" Tabt:r -45.424 02 11 3.178 0 . 69 ~ Overall Martindale -228. 13 0.331 -5 .9 17 12.67 0.53 b Taber -72.605 0.50'+ 6.788 -22 1.0 0. 6 1 " "Signifi cant at 5%; "Significant at 1% crimp distribution plays an important role in the fabric. Wear resistance is more li ke ly to be a complex abrasion resistance of fabrics and higher the cri mp interaction of several properties whose relati ve imbalance, the lower wi ll be the abrasion resistance. influence is different in different end uses. The difference in warp and weft deniers will result in The study has enabled ranking o f silk fabrics in the the warp yarns bending freely while the weft yarns order of merit of the ir resistance to abrasion wit h remain uncrim ped. This conditi on wi ll lead to an actual chi ffon and georgette having the lowest values and reduction in geometric area of contact and to an earl y taffetta and / exhibiti ng the best abrasion damage to the warp yarns. The damage can be delayed resistance. Abrasion of texti Ie fabrics is a so complex with more warp crowns in a given area of fabric. Weft, mechanism that the effect of individual structural being a highly irregul ar yarn in spite of having a larger parameter is often masked by th e interactions with diameter, is more prone to damage and this perhaps each other. This is well reflected in the difference in makes the cover factor as one of the parameters behaviour of different varieties o f silk fabrics. The explaining the abrasion resistance along with crimp abrasion resistance of sil k fabrics can be increased by ratio and warp densi ty. increasing the geometrical area of contact between th e Taffefa--Endslinch happens to be a significant cloth and the abradant which can be done by usi ng the parameter explaining the abrasion resistance. Taffeta is hi gher cover factor and equal cro wn heights in warp a warp flush fabric and the abrasion resistance of warp and weft. However, the exact nature of influence of flush fabrics is known to be a function of warp density, these parameters becomes specific to the type of other factors being the s ame~. It is observed that the fabric that includes all possible structural variations hi gher number of warp crowns per square in ch of the and th eir interactio ns. fabric reduces the normal load per crown, th ereby imparting better abrasion resistance. References Crepe--Crepe fabrics have untwisted or low twisted I Tortora Phyili s G, Ullderstalldillg Textiles (Mac mil la n yarns in the warp and high twisted yarns in the weft. It Publishing Company, New York ). 1987. 48 1. 0 is reported 4 that the abrasion resistance is related to the 2 Taylor H M, Textiles, 7 ( 1 78) 36. di ameter of th at part of the textile structure which is 3 Lord P R & Mohammed M H. Weal'il!g: COll ve rsioll (!f Yam to Fabric (Marrow Publishing Co Ltd. Eng land). 1982. 175. exposed at the rubbing surface. In the case of crepe 4 Stanl ey Backe r & Tanenhaus S J. Text Res J, 2 1 ( 1951 ) 635. fabrics, the hi gh twisted weft yarn s relax on , 5 Stout E E & Moseman M B. in Textile Fibres. Yams (llId imparting a crinkled and uneven surface to the fabric. Fabrics-A COlllparatil'e SlIrl'ev of tlieir Belwl'iollr \\'itli Thus, the hi ghly twisted yarn s in th e crepe fabric Special Rej erel/{'e to , edited by E R Kaswe ll (Re in hold Publi shing Corporatio n, New Yo rk ). 1953, 3 19. provide less contact with the abradant and the warp 6 Peirce F T , J Text IlI st, 28 ( 1937) 181. yarn takes the brunt of the abrasive action. It is 7 Lo max J. J Text /11 .1' 1, 28 ( 1937) 218. confirmed 4 th at the abrasio n resistance is related to the 8 Booth J E, Prillciples '!f Textile Testillg (Butterworth diameter of tex til e structure whi ch is exposed at the Scienti fi co Lond on), 1983, 266. rubbing sLllface and in thi s case it is warp. 9 Hicks E M & Scorggie A G, Text Res J. [8 ( 1948) 4 16. 10 ASTM D3884-92 and IS 12673 : 1989 4 Conclusions I I Kaswell E R, Textile Fibres. Ya m s alld Fabrics-A COlllparative SlIn'ey (! f tli eir Beliw'iour witli Special The abrasiv e wear of silk fabrics depends, to a Referellce 10 Wool (Reinhold Publishing Corporation, New considerable extent, on the con :-~ ru c t i o n o f yarn and York), 1953, 301.

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