Effect of Yarn Type, Sett and Kind of Huck-a-back Weave on Some Characteristics of Towelling Fabrics

Transcription

1 Indian Journal of Textile Research Vol. 8, March 1983, pp. 1-5 Effect of Yarn Type, Sett and Kind of Huck-a-back Weave on Some Characteristics of Towelling Fabrics G S BHARGAVA, S MAHAJAN, S TONDON & R GUPTA The Technological Institute of Textiles, Bhiwani Received 13 September 1982; accepted 4 January 1983 ( The effect of type of weft yarn, weft sett and kind of huck-a-back weave on water absorbance, abrasion resistance in dry and wet states, and tensile and te.arstrengths of towelling fabrics has been investigated. It has been observed that if the final count of weft yarn is the same, the use of single yarn associated with lower sell leads to a highly absorbent towelling fabric. Huck-a-back weave having relatively longer warp floats than weft floats, using the same yarns and fabric construction but higher ends than picks per inch, produces a fabric with improved strength and absorbance. ) In the production of simple structure towelling fabrics, standard atmosphere (65 ± 2% RH and 20 ± 5 C) for huck-a-back weave is used extensively, as it produces a 24 hr. sufficiently absorbent and durable fabric!. If the For measuring water absorbance, two main counts of warp and weft are same, the fabric methods, viz. sinking time method and centrifuge characteristics become dependent upon the type of method, were used. In the first method, sinking time in fibre2, yam 3, weave and sett4. In the present study, seconds was noted and in the second one, the the effects of weft yam structure, weft sett and kind of percentage water absorption was calculated as huck-a-back weave on water absorbance, abrasion resistance in dry and wet states and tensile and tear b 0 Wwa Water absor ance, %=w- ds x 100 strength of towelling fabrics have been investigated. The huck-a-back weaves selected in this study were 8 x 8 weave repeat size. Materials and Methods Cotton yam of 2/20' spun from 1-34 cotton [two fold-13.3 turns per inch (S) and single-17.0 turns per inch (Z)] was used as warp and three different yams, the first one of IOscount spun from 60% 1-34 plus 40% desi cotton [16 turns per inch (Z)], the second one of 2/20sT (with doubling twist) as of warp and the third one of2/20sp (without doubling twist) both spun from 1-34 cotton, were used as weft. In all, 30 fabric samples with 44 x 40 and 44 x 44 nomii1al construction, each using three different weft yams and five kinds of huck-a-back weaves, as shown in Fig. 1, were prepared. The fabric samples were prepared on the same loom and finished under identical co'nditions. Prior to testing, all the fabric samples were conditioned in a Fig. I-Huck-a-back weaves used where W wa is the weight of water absorbed by the specimen; and Wds, the weight of dry specimen. The fabric samples, both in dry and wet states, were tested for flat abrasion on CSI-stoll-QM universal wear tester. The end point was determined by abrading the specimen until all the fibres in the centre of the abrasion zone were worn off and was specified by the number of cycles. The tensile strength was measured using German tensile strength tester type FW GW 500, with 20 cm gauge length and 5 cm wide specimen. The tear strength was determined using Instron tensile strength tester with 4 in tear distance. Results and Discussion The characteristics of the fibres and yams used in the study are given in Tables I and 2 respectively. The fabric characteristics of the experimental fabrics are given in Table 3. Water absorption-the water absorbance values, measured by two methods, are given in Table 3. In the sinking method, a highly absorbant fabric takes least time for sinking, while in the centrifuge method, the same retains maximum water. The data in Table 3 show that the fabric with single 10' weft is more absorbent than those with 2-pIy

2 10' -- Desi Cotton ,0 strength, Actual Lea 20' '-" No WeftWater 41.5 twist 2/20' TPI Parallel Type (Nominal Twisted kgof absorbance Actual count yarn count) Abrasion ~.~~ , l --- '-'--~"~"-'--'----'-'-~---' type Tear Tensile strength strength -_.,----_ ;:j.._~._ kg Weft Warp kgkgkg : q Wet cycles Centrifuge ' method, cycles --i~ J I 'p11""1'1'1" I D "ll<i"iv' I PI ! "HI' Dry , II' "I' /" 'to II' Reed resistance x Pick: 44 INDIAN Reed x 40; x 49.5 JPick: x 40 TEXT44 actual RES, x 40; 49.5 VOLx 40 8, Table MARCH actual 2- Yam Characteristics ',J \ 1 I I' 1,'1 II!I'II'I' II -1>11 ill ifllll";1 'I. II~ '" "r

3 BHARGAVA et al.: EFFECT OF YARN CHARACTERISTICS & WEAVE ON TOWELLING FABRICS twisted - 2/20sT and 2-ply parallel - 2/20sP. The probable reason for such a trend is thatthe single IOs yarn had been prepared from J-34 (60%) plus desi cotton (40%). Desi cotton being of shorter and coarser fibres than J-34 will have better capillary action for water absorbance rating, thereby absorbing water at a faster rate. It is further observed that folding twist affects adversely the water absorbance of a fabric. The reason for this is that the folding twist restricts the penetration of water more due to improved binding of fibres. The results for different weft sett fabrics reveal that the low weft sett fabrics because of their loose structure and longer warp float provide greater capacity to hold water molecules, thereby exhibiting higher absorption capacity!. Comparison of water absorbance values of fabrics of different weaves reveals that the fabric with weave No. I exhibits maximum absorbance and the one with weave No.4 shows the minimum water absorbance. This is because weave No. I has the maximum number of long floats associated with the long floating thread separated by plain interlacing threads; this enables long floating threads to absorb water at a quicker rate due to the large surface exposed to water!. On comparing the values for fabrics woven as per weaves No.3 and 4 it is seen that a fabric with better water absorbance may be obtained by using a huck-aback weave with longer floats of warp than weft when the thread density of warp is higher than that of weft. Abrasion resistance-it is seen from Table 3 that the wet abrasion of the fabric samples is higher by 35-70% compared to dry abrasion. In most cases, the magnitude of increase in abrasion resistance is higher for single yarn fabrics prepared from coarse and short fibres, and fabrics having a high pick level. This is in agreement with the finding of Mc Nally et al.5. It has been observed that the use of a single yarn prepared from short and coarse fibres in place of 2-ply yarn gives a fabric with improved dry and wet abrasion. This is due to the superior mechanical properties and large diameter of desi cotton fibres. Another reason for this is that the single yarn being bulkier than 2-ply yarn provides a relatively more flattened surface to the abrader. This is in agreement with the finding of Sengupta et al.6 According to Backer 7 and Backer and Tanenhaus8, a bulkier (i.e. low compressive modulus) yarn gives a fabric with higher abrasion resistance by reducing the pressure at crowns. Further, the folding twist in 2-ply yarn, on similar grounds, affects the abrasion resistance adversely. The effect of folding twist in 2-ply yarn on abrasion resistance in both dry and wet states offabrics is marginal. As would be expected, a fabric having the same weave and yarn, but a higher pick level, exhibits better abrasion resistance. This is because of the improved fibre binding and fibre to fibre cohesion caused by the increase in pick density. Fabrics woven as per weave No. I show maximum abrasion resistance, and those woven as per weave No. 4, the minimum abrasion resistance. This is possibly due to the greater number of long floats in weave No. I, which, in turn, provide a relatively large flattened surface to the abrader. A comparison of abrasion resistance values of fabrics woven as per weaves NO.1 and 3 reveals that a huck-a-back weave, in which long floating threads and plain interlacing threads are arranged alternately, gives a fabric with better abrasion resistance than a huck-a-back weave in which they are arranged in pairs. It is also obvious that a fabric with higher abrasion resistance may be obtained employing a huck-a-back weave having longer warp floats than weft floats, if in the construction of the fabric the warp thread density is more than the weft thread density. This is evident from the abrasion resistance values of the fabrics having the same construction but woven as per weaves No.3 and 4. Tensile strength- The tensile strength in both warp and weft directions is highest for the fabric with 2-ply twisted weft among the three types of weft yarns used. Further, the tensile strength is independent of the fabric sett and the type of weave used (Table 3). This may be ascribed to the superiority of2-ply twisted yarn which is more regular and better bound than 2-ply parallel and single yarn of the same final count. Use of equivalent single yarn produces the weakest fabric. Increase in weft sett, keeping other parameters constant, results in increase in both warp-way and weft-way tensile strengths. This is.due to the improved cohesiveness and better binding of fibres and yarns, leading to increased weft sett. This is in agreement with the finding of Taylor9. Comparison of the tensile strength of fabrics of five different weaves (Table 3) reveals that the fabric woven as per weave No.2 has the maximum strength in both warp and weft directions and that woven as per weave No.4 has the minimum strength. The higher strength in weave NO.2 may be attributed to the higher number of interlacements in the weave structure~ which results in higher cohesiveness of warp and weft yarns. Tensile strength values of the fabrics woven as per weaves No. I and 3 reveal that a huck-a-back weave with long floating and plain interlacing threads arranged alternately produces a stronger fabric than a huck-a-back weave having these threads arranged in pairs. Comparison of the tensile strengths of fabrics woven as per weaves No.3 and 4 reveals that a fabric with higher tensile strength can be obtained by 3

4 INDIAN J TEXT RES. VOL 8. MARCH 1983 employing a huck-a-back weave having warp floats longer than weft floats. Tear strength-it is seen from Table 3 that the fabric with 10s single weft exhibits lower tear strength compared to 2-ply twisted and 2-ply parallel yarn fabrics. This may be due to the larger diameter, higher bulkiness and lower strength of single yarn compared with 2-ply twisted and 2-ply parallel yarns of equivalent count. The first two factors reduce the actual space between the threads in the cloth and consequently the tendency to slip, which, in turn, results in reduced tear strength. The third factor, i.e. yarn strength, affects the tear strength directly. The tear strength is shown to be proportional to the single thread strength of the threads broken, other factors being the same. It is seen from Table 3 that folding twist improves the tear strength of the fabrics in both the directions. This is due to the fact that folding twist increases both the yarn strength and the slipping tendency of threads which become rounder in cross-section. The lower extensibility ofl-ply twisted yarn is further responsible for the higher tear strength. This is in agreement with the finding of Sengupta et a/. I> The results given in Table 3 further show that increase in weft sett causes increase in tear strength in both warp and weft directions. According to Harrison 10 change in thread spacing may be accompanied by either an increase or a decrease in tear 'strength, depending on other features of fabric construction. Fabric woven as per weave No.2 shows maximum tear strength, whereas that wovep according to weave No.4 shows the minimum tear strength. This may be for the reason that each thread of weave No.2 has warp or weft float of three or more thread-like twill and none has plain interlacing; on the other hand, weave No.4 has four picks in pairs, plain interlacing. Therefore, in weave No. 2",the slipping of threads, at the act of tear, would be highest and in weave No.4 the same will be inhibited to the maximum extent. A comparison of the tear strengths of the fabrics woven as per weaves No. I and 3 shows that both ways, the tear strength of the fabric woven as per weave No. I is higher than the tear strength of the fabric woven as per weave No.3. The probable reason for this is that weave No. I has plain and floating threads alternately, while weave No.3 has these in pairs. Consequently, the slipping tendency of threads is more in the former than in the latter. Therefore, to obtain a fabric with better tear strength, alternate combinations of plain and floating threads in the construction of huck-a-back weaves should be preferred. Comparison of tear strengths of fabrics woven as per weaves No. 3 and 4 shows that a fabric with improved tear strength may be obtained by selecting a huck-a-back weave with longer floats of warp than weft. Backer and Tanenhaus8 and Teixeita et a/.11 have shown that the type of weave used in a fabric has a major effect on tear strength. The results of the present investigation show that among the various huck-a-back weaves tried, weave No. I imparts the maximum water absorbance to the fabric, but in respect of abrasion resistance, tensile strength and tear strength, it comes next to weave No. 2. Therefore, weave No. I is the best among the five weaves taking all the fabric characteristics into consideration. -Comparison of the data for 44 x 40 nominal sett fabric with those for 44 x 44 nominal sett fabric reveals that using higher sett of weft there is an effective decrease in water absorbance accompanied by increase in abrasion resistance, tensile strength and tear strength. It may be concluded that with single yarn as weft, 44 x 40 construction and weave No. I, the highest water absorbance and optimum serviceability values are obtained in the resulting fabric. Conclusions (I) Single yarn prepared from a mixing of short and coarsefibre cotton improves the water absorbance rate and abrasion resistance, but adversely affects the tensile strength and tear strength of the fabric. (2) The folding twist affects the water absorbance and abrasion resistance adversely, but improves the tensile strength and tear strength of the fabric. (3) Increase in pick density causes improvement in fabric quality by increasing abrasion resistance and tensile and tear strengths, but affects the water absorbance of the fabric adversely.. (4) Weave No. I is the best among the weaves tried and the lower sett, i.e. 44 x 40 nominal, is the better of the two setts considered. (5) In the construction of a huck-a-back weave, floating and plain interlacing threads should be arranged alternately in association with longer floats in warp direction to obtain desirable characteristics. Acknowledgement. The authors are thankful to Prof. R.C.D. Kaushik, Director, TIT, Bhiwani, for permission to publish this paper. References I Bhargava G S. Mukherjee S & Chatterjee S, Indian J Text Res, 6 (1981) Kaswell E R. Text Res J. 16 (1946) Robertson A F. Text Res J. 20 (1950)

5 _e ~U "-'~'i' BHARGAVA I!t uf.: EFFECT OF YARN CHARACTERISTICS & WEAVE ON TOWELLING FABRICS 4 Shrinagabhushan, Shri Kanthiah S & Muniswamy D V, Text Dig, 20 (1959) Mc Nally J P & Mc Cord F A, Text Res J, 30 (1960) Sengupta A K, De D & Jayaraman K S, Proceedings, 12th Tech ConfofATlRA, BTRA & S/TRA (BTRA, Bombay) 1971, Backer S, Text Res J, 21 (1951) Backer S & Tanenhaus S J. Text Res J. 21 (1951) Taylor H M, J Text/nst, 50 (1959) T-16L 10 Harrison P W, J Text/nst, 51 (1960) T-91. I I Teixeira N A. Platt M M& HamburgerW J. Text ResJ. 25(1955)