Indian Journal of Research Vol. 6, March 1981,22-27

Study of Pilling in / Blended Fabrics

V R SIVAKUMAR & K P R PILLAY South India Textile Research Association, Coimbatore 641014 Received 16 January 1980; accepted 13 December 1980

The pilling characteristics of commercially available polyester/cotton blended fabrics in the grey and finished conditions as well as of those produced in the laboratory under controlled conditions ha ve been investigated. The structure of pills and the nature of fibres that go into pill formation in various types offabrics have been examined microscopically and the influence of various fibre, yam and fabric factors on pilling tendency has been assessed. An analysis of the conditions giving rise to pilling on fabrics shows that its development is almost always promoted by a number of factors, the most important of which an: the physical characteristics like length, fineness, etc. of the component fibres, the yam twist and the density and type of weave of the fabric. Processes like singeing, cropping and heat setting reduce the pilling tendency to a significant extent and are the most effective ways of controlling pills.

Pills are bundles of entangled fibres formed on the the part of the fabric near the surface are pulled out surface of fabrics during rubbing or wear (Figs. I and and stand in a form, (2) the fibre ends of these 2). It is a fabric fault which has presented serious protruding fibres get entangled with other contiguous problems with the increasing use of polyester/cotton fibres by some abrasive action, and (3) the pills thus blends. The high strength and flex life of polyester formed are worn off or pulled away from the fabric. In fibres prevent easy wear off of pills, while their a given fabric construction, the rate or extent at which electrostatic properties attract foreign matter which these stages occur is determined by the physical may serve as a nucleus for pill formation. The characteristics of the fibres which compose the fabric. advantages like durability, aesthetics and Although the general problem of pill formation has qualities of polyester/cotton blends may be been studied extensively by many workers, only stray considerably offset by the pilling tendency of these references are available in literature as to the probable fabrics and can pose serious problems of appearance in causes of pill formation in polyester/cotton blended apparel fabrics. fabrics. Pilling studies have shown that there are three There is also need to investigate the influences of distinct stages in the life span of a pill: (1) fibres from processes like singeing and heat setting at

Fig. 1 Pill, appearing on polyester/cotton fabrics Fig. 2 Microscopic appearance or a pill

22 SIVAKUMAR & PIllAY: PILLING IN POLYESTER/COTTON BLENDED FABRICS

different temperatures and for different durations on photographs, and (ii) by counting the pills per u'lit the pilling tendency of fabrics. area. The fabrics could be divided into five groups, The present study was aimed at exploring these depending upon the number of pills per unit area. It factors in detail and suggesting optimum fibre, yarn was thus possible to get a quantitative measure of the and processing factors for reducing pilling in number of pills in each photographic standard .. polyeste"rtcotton blended fabrics. The different types of pills in the grey and finished fabrics were plucked out with the help of forceps, Materials and ~ethods teased open with dissecting needles and examined The investigation was carried out in two phases. In the first phase, suiting fabrics made from polyester/ Table I-Details of Polyester/Cotton Blended Fabrics cotton blends (in grey and finished forms) collected Pilling Fabric Blend Yarn Remarks from some of the member mills were used. Details sample construc• prop• treat• No. tion ortion ment regarding the respective yarn, fabric and processing P:C factors were also collected. These fabrics were 52 x 48 PI 25:75 Singed 3 denier polyester subjected to pilling tests on a laboratory pilling tester. 2/32 x 2/32 In all, 20 fabrics from six mills were available for the 52 x 48 study. P2 67:33 do do 2/32 x 2/32 In the second phase, fabrics having different 52 x 48 constructions were woven in the laboratory from P3 50:50 do do different types of polyester/cotton . The 2/32 x 2/32 following variables in fibre, yarn and fabric 52 x 48• P4 67:33 do 1.2 denier polyester construction weri introduced to get an idea of the 2/32 x 2/32 influence of these factors on pilling. 52 x48 P5 --- 67:33 do 2.1 denier polyester 2/32 x 2/32 Blend proportions (polyester: cotton) : 67:33; 50:50 and 33:67 52 x 48 Polyester denier : '1.2, 2.1 and 3.0 P6 do low twist yarn 2/32 x 2/32 67:33 Twist/in : 20, 22 and 26 3 denier polyester Length of polyester : 38 mm and 51 mm 52 x48 Types of : Sankar-4 and Varalakshmi P7 67:33 do High twist yarn Yarn ply : single and double 2/32 x 2/32 3 denier polyester Picks/in : 40, 45 and 56 52 x48 Singeing : single and double P8 25:75 do Normal twist yarn 16x 16 ·3 denier polyester The details offabric constructions used in the study 52 x48 are given in Table I. In all 17fabrics were available for P9 67:33 do do 16x 16 the investigation. Most of the fabrics woven in the laboratory were made from singed yarns. Small 52 x 48 PI0 50:50 do do lengths of fabrics were also finished with the help of a 16 x 16 member mill in the normal way. This was done because 52 x48 the pilling tendency of finished fabrics is more P12 67:33 do Open-end spun yarn 2/32 x 2/32 important to the consumer than those of untreated or 3 denier polyester grey fabrics. 52 x 48 The pilling resistance of the fabrics was measured as P13 67:33 do Varalakshmi cotton 2/32 x 2/32 per the test method recommended by leI using a 3 denier polyester laboratory pilling tester. The pilling tester consisted of 52 x48 twin wooden boxes mounted on an axis capable of P14 3 denier polyester rotation. The samples were ,sewn on special rubber 2/32 x 2/32 67:33 Unsinged 52 x40 tubes, which were placed inside the boxes. The interior P15 67:33 Singed do of the latter is lined with Neubar cork. The boxes were 2/32 x 2/32 revolved at 60 rpm and the revolutions were recorded 52 x 56 P16 67:33 do do on a pre-set electric counter. After the required number 2/32 x 2/32 of revolutions, the instrument was stopped and the fabric specimens were evaluated for pilling. Eight 52 x 48 67:33 Double do samples were tested for each type of fabric. P17 2/32 x 2/32 singed The evaluation of pIlling tendency was done by (i) p, polyester; C, cotton. comparing the treated samples with the ,standard

23 INDIAN J. TEXT. RES., VOL. 6, MARCH 1981 -'~--i Table 2-Variation in Pilling Tendency of Commercial Fabrics-Grey and Finished

Mill Sample code No. -_._------, ---~------~----,------,._------A B c D E Grey3121238Fini- FGshed shed Fini- --- Grey Fini- Grey Fini- Grey Fini-12 Grey Fini- Grey shed shed shed shed .., 1 .l,.••..i. 1.<45 4715321653187119935611 8 10& 32 '~"}" 142 17348 22

4

5

, under tlie microscope to get an idea of the type of fibres Table 3-·ElTect of Weave on Pilling Tendency 2/32s x 2/32s Twill F2lbric Finished1687 Grey 64 x48 85 x 52 Someand fortign of these matterparticul?rs piUs thatwere go alto into photographed. the body of the pills. 53145 2/32s x 2/328 Plain Results land Discus..'iion Analysis of commercial fabrics-The variations in pilling tendencies of commercial fabrics in grey and finished states are given in Table 2. It is seen that there

areais cons~erable i~ the grey variation state not in onlythe number among of the pills/unit fabrics producfd by different mills, but also among the fabrics reduce pilling. The long floats in twill weave expose longer lengths of fibres to the abradant media and in and .5 -531 respectively. This means that the addition, pilling of the fibres from the yarn is produc1dvaria:j· nsby in the fihre, same yam mill, theand ranges processing being 32-222factors facilitated. These circumstances lead to the conclusion that pilling can be reduced by the correct choice of emp!o)jedmills c~n cause in the 7 - manufacture 18times differences of fabrics in the by number different of weave. pills. ! Effect of blend composition on pilling- The effect of blend composition on the pilling tendency of to 87 I' lmit area, whic;h is on the average 85% less commercial suting fabrics is obvious from the data thanThe~'umber t at in the of grey piBsin state. finished Fabric fabrics ranged processes from 6 presented in Table 4. emplo~ed in polyester/cotton blended fabrics can, It is seen that the number of pills is significantly lower in the fabric containing higher proportion of tenden y of these fabrics. polyester fibre in the grey state. The increase in the there~te,The ata bring made significant available by reduction the mills in were the further pilling proportion of cotton from 33 to 51% has increased the number of pills in the grey fabric by more than twice. reasonfanalyz~d for to the see differences whether there in the are number any perceptible of pills Possibly, the higher number of short and relatively loose fibres present in the cotton component are easily obtain~dEffett of with v.'eareon different pilling-The fabrics. effect of weave on rolled up into pills during the pilling test. However, it is interesting to note that this tendency is reversed in the reason~blypilling I tendency constant when is evident other from factors the data are presented kept finished fabric. Probably, the cropping, fabric singeing in Ta~e 3. and heat setting operations during finishing reduce the fuzz forming tendency of cotton fibres considerably and there are fewer piUs in the finished fabric. Here

numbpicksIn sf,'iteI' eof twill ofpills the woven than slightly the fabrics plain higher give woven-fabric numberSUb, stantially of both ends higher in and the again, the finisbe," t'ahrics of both the blend grey ~nd fj,.ished conditions. Probably the greater composition,j show ;;,'ns;derable reduction in the numb~r of interlacings and short cross-lengths in the number of pm' E.Uecf f ;t ""ft on pilling-Fabric having freeplain e~ds toven to emergefabrics diminish on the fabric the opportufiity snrfaces and for thus the filament Wi',' ,;;,ited the lowest number (31) of i 24

, .,i SIVAKUMAR & PILLAY: PILLING IN POLYESTER/COTION BLENDED FABRICS pills/unit area among the commercial grey fabrics. The Analysis of Laboratory Woven Fabrics number of pills is further reduced to 21 in the finished Effect of denier on pilling-The lowest denier (1.2) state. In the case of fabrics incorporating filament exhibits the lowest number of pills when other factors yarns, pilling is impossible unless wear and abrasion are constant. There is practically no difference between break and sever the filaments to produce hairiness and 2.1 and 3.0 denier fibres as regards their pilling pile. tendency. It appears that comparatively large changes in denier are required to effect significant changes in Effect of fibre types on pilling-The data presented the critical height of fibres. This is contrary to the in Table 5 show the pilling tendency of two types of observations of other workers, where finer deniers are polyester fibres (PI and P2) produced by two different reported to give rise to more pills due to their increased manufacturers when blended with cotton and woven flexibility than coarser ones. The present trend in the into fabrics of almost identical construction.It is seen case of fine denier fabrics may be because of (i) the that fibre P2 gives comparatively higher number of greater number of fibres in the yarn cross-section, and pills (47) than PI (32). However, on finishing, the (ii) the higher friction; the fine denier fibres exert differences between the two fibre types are reduced and against surrounding fibres due to greater area of both the fabrics show almost the same number of pills. contact and the consequential resistance to fibre Since the frictional and mechanical properties of migration to the yarn surface. polyester fibres differ, their pilling tendencies may be expected to differ. During fabric finishing, the effect of Effect offibre length on hairiness of blends-Data on surface finishes is removed and the two types behave the effect of using cottons differing in staple length on similarly with respect to the number of pills. the hairiness of polyester-cotton blends are given in Table 7. It is seen that Varalakshmi cotton,which has a Effect of stage of blending on pilling-The stage at 2.5% span length of 37.3 mm, gives significantly lower which the polyester component is blended appears to number of pills (5.0) than Sankar-4 (15.0), which has a have a singificant effect on the pilling tendency of grey 2.5% span length of 31.6 mm. The longer fibres may be fabrics made from the blends. Blending in the expected to have greater in length and less blowroom appears to produce lesser number of pills protruding ends from the body of the fabric than short than blending at the drawframe stage on grey fabrics fibres. Moreover, longer fibres show greater resistance (Table 6). The differences, however, vanish when the to migrate towards the yarn surface. fabrics are finished and both types behave identically. The intimacy of blending that takes place in blowroom Effect of blend compositien on pilling-« The effect of blending probably restricts the removal of fibres from blend composition on the pilling tendency has been the yarn surface during pilling tests. However, more investigated for one fabric construction. Polyester work is necessary to confirm this behaviour. fibres (1.5 denier) in 67:33, 50:50 and 25:75 blend proportions were used to spin 2/32s yarn for the production of suiting fabrics. The results show that the Table 4-Effect of Blend Composition on Pilling Tendency number of pills decreases steadily as the proportion of of Commercial Suiting Fabrics

Fabric Grey Finished particulars Table 6-Effect of Stage of Blending on Pilling Tendency 67:33 PIC 49:51PIC 67:33PIC 49:51 PIC MiliA MillB 2/32s x 2/32s Blowroom blending Drawframe blending 45 119 16 9 64x48 Grey Finished Grey Finished P, polyester; C, cotton.

47 II 222 II Table 5-Effect of Fibre Types on Pilling Tendency Table 7-Effect of Fibre Length on Hairiness of Blends Fabric Fibre Fibre particulars type type PI P2 Cotton Fibre length (2.5% Mean of pills 2/40s x 2/40s 32 47 Grey fabric variety span length), mm 80x 56 2/40s x 2/40s Varalakshmi 37.3 5 10 11 Finished fabric Sankar-4 31.6 15 80x 68

25 INDIAN J. TEXT. RES .. VOL 6. MARCH 1981 polyester decreases (Table 8). The number of pills in and weft have lower number of pills than 25:75 P, C blended fabric is only one-fifth of that in approximately equivalent fabrics with single yarns in 67:33 blended fabric. This trend in the case of singed warp .and weft. Doubling reduces pilling, because yarn fabrics is similar to that observed in finished fabrics containing two-fold yarns are more tightly commercial fabrics. Singeing removes the fibre ends constructed. and short fibres which are predominant on the surface Effect of number ofpicks 0[1 pilling-Data presented of PIC blends having a high proportion of cotton. in Table II suggest that fabrics with more picks pill Effect of twist in yarn on pil/ing- Yarn twist has an less, because the fabric is tightly constructed. The important bearing on the compactness of yarn and number of pills is minimum (5) when the number of degree of mobility of individual fibres. The influence of picks per inch is maximum (56). It appears that when twist in yarn on pilling was determined by giving three the fabric structure is open, the freedom for fibres to levels of twist to warp and weft yarns for a series of migrate towards the yarn surface also increases, polyester/cotton blended fabrics. The fabrics were facilitating the formation of pills. The difference in the identical, except for twist factors of the yarns. Data number of pills for fabrics having 40 and 45 picks per given in Table 9 show that increase in twist reduces the inch is small and probably not significant. pilling of 67:33 polyester/cotton fabric, because the Effect of singeing on pilling-Singeing or burning of fibres are more tightly held in the fabric. As the yarn protruding fibres facilitates the reduction of pilling density increases with increase in the twist factor, the tendency not only by removing the short and loose fibres are pressed more closely against each other, with fibres from the yarn surface, which would otherwise the result that the number of fibres which might be entangle themselves with adjacent ones, but also by freely displaced in the yarn as a result of mechanical heat-setting and stabilizing the yarn structure. action decreases considerably. Many workers, The influence of singeing on pilling tendency is therefore, recommend that for yarn containing evident from the results given in Table 12. It is seen that synthetic fibres, the twist factors be increased above the number of pills in singed yarn fabric is about one- the standard values. twentieth of that in untreated yarn fabric. When Effect of yarn ply on pilling- The fabrics made from singeing is repeated, i.e. the yarn is double singed, the single yarns are more prone to pilling than those number of pills is still reduced to 20% of the previous produced from ply yarns, the reason being that the case.It follows that singeing and double singeing are second twisting causes the fibre protruding on the effective steps for reducihg the number of pills on surface of single yarn to be secured by being moved to polyester/cotton blended fabrics. some extent into the yarn. Data presented in Table 10 show that fabric with Table IO-ElTect of Yarn Ply on Pilling Tendency two-fold yarns of different blend compositions in warp Yarn ply Blend composition

P:C P:C P:C Table 8-ElTect of Blend Proportion on Pilling Tendency 67:33 50:50 25:75

Blend composition Mean of pills Single 17 14 6 Double 15 12 3 P C o ~o /0 P, polyester; C, cotton

25 75 3 50 50 12 Table II-ElTect of Number of Picks on Pilling Tendency 67 33 15 Picks/in Mean of pills P, Polyester: C, Cotton. 40 10 45 15 56 5 Table 9- ElTect of Twist in Yarn on Pilling Tendency Table 12-ElTect of Singeing on Pilling Tendency Twist (TPI) Mean of pills Type of finish Mean of pills 20 10 22 15 Unsinged 336 26 9 Singed 15 Double singed 3

26 SIVAKUMAR & PILLAY: PILLING IN POLYESTER/COTION BLENDED FABRICS

The entangled fibre pill contains predominently Table lJ-ElTect of Duration and Temperature of Heat polyester fibres, with a few cotton fibres trapped in Setting on Pilling Tendency between. The seed coat fragments sometimes come even in combed cotton due to the poor cleaning Period 210°C195°C230°C3232 10.07.55.0180°CControlsample336 see 45 336 efficiency of the processing machines or due to the 25 incidence of these impurities in large quantities in many long staple cottons used in the present study for making polyester cotton blends. These seed coat fragments having short fuzz hairs act as the nucleus for entanglement pill formation. Polyester fibres on yarn Effect of duration and temperature of heat setting on or fabric surfaces get softened and melt during singeing pilling-The effect of setting polyester-cotton fabrics or heat setting. This causes the fibres to adhere to one at different temperatures ranging from 180° to 230°C another or get set in a hooked position. These fibres for two durations (25 and 40 sec) was investigated for cause entanglement during abrasion and form the one fabric type. The number of pills which is 336 in nucleus of pills. In so far as the appearance and appeal untreated fabric practically reduces to zero when the characteristics of fabrics are concerned, pills having fabric is heat set at 230°C (Table 13). seed coat fragments spoil the appearance of fabrics With higher durations, the number of pills is much more than pills consisting only of fibres. generally low, especially if the setting temperatures are low. Thus, at 180°C, the number of pills is reduced Conclusion from 10to 5, when the setting period is increased from An analysis of the conditions giving rise to pilling on 25 to 45 sec. But at 230°C, there is practically no polyester/cotton fabrics shows that its development is difference in the number of pills when fabrics are set always promoted by a number of factors. Fibre for different durations. characteristics like length and fineness of the Pilling in open-end (DE) yarn fabrics-Since OE component fibres influence the pilling tendency of yarns have more twist and show less hairiness due to fabrics to a significant extent. The yarn factors that the shorter length of fibres protruding from the yarn support pilling are (I) low twist, (2) hairy and bulky surface, the fabrics made from these yarns may be yarns, (3) single yarns, and (4) high proportion of expected to show less pilling tendency than the polyester components. corresponding ring yarn fabrics. This is confirmed by Wherever possible, weaves with maximum observations on the pilling of polyester/cotton blended interlacings could be used with advantage. Long floats OE yarn and ring yarn fabrics. OE yarn fabric shows 6 expose longer lengths of fibres to the abradant and pills as compared to 15 for the ring yarn fabric. increase the pilling tendency. Structure and· composition of pills-Pills were Singeing, heat setting and cropping reduce pilling removed from the surfaces of polyester/cotton blended tendency to a significant extent and are the most· fabrics in the grey, heat set,' singed and finished effective ways of controlling pills. conditions and examined under the microscope. The pills were approximately spherical and consisted of Acknowledgement tangled masses of fibres attached to the fabric by The authors wish to express their sincere thanks to several unbroken fibres. These anchoring fibres are Shri K. Sreenivasan, Director, SITRA for encourage• mostly polyester in blends with high polyester content. ment and guidance during the work. They are thankful The pills contain both polyester and cotton, the to Sarvashri K.S. Shankaranarayana and Veluswamy polyester fibres securing the pills to the fabrics being for useful discussions and for arranging to have the surrounded by trapped broken cotton. fibres which fabrics woven. The assistance ofShri Mohan and other increase the size of pills.. colleagues of the Physics Division in testing and of Examination of scores of pills under the microscope M/s Madura Coats for finishing the polyester/cotton revealed that the fibres involved in making them are fabrics is acknowledged. entangled and they can be broadly divided into three groups:' (i) entangled fibre pills, (ii) pills having seed References coat fragments in the core, and (iii)pills having molten, 1 Gintis D & Head E J, Tex/ Res J, 29 (1959) 578. 2 Conti W & Tassinari E, J Tex/lns/, 6S (1974) 119. fused or heat set hooked polyester fibres in the core. 3 Brand R H & Bohmfalk B M, Text Res J, 37 (1967) 467. The first two types of pills are found in grey, singed and 4 Baird M E. Hatfield P & Morres, J Tex/lns/, 47 (1956) TI8!. finished fabrics, but the third type is found only in 5 Palel P D, J Text Ass, 37 (3) (1976) 101. singed yarn fabrics or heat set and finished fabrics. 6 Lutskya T S, Technol Text Ind, USSR, (I) (1966) 33.

27 I J