Properties of Polyester/Wool Parent and Air-Jet Textured Yarn and Their Fabrics

Indian Journal of Fibre & Textile Research Vol. 27, June 2002, pp. 156- 160

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Properties of polyester/wool parent and air-jet textured yarn and their fabrics

V K Kothari" & S K Bari

Department of Textile Technology, Indian Institute of Technology, New Delhi 110016, India Received 14 July 2000; revised received and accepted 27 February 2001

Air-jet texturing of polyester/wool blended spun yarn has been carried out and woven and knilled fabrics have been produced using parent and textured yarns. The properties of parent and textured yarns and of the fabrics produced using par­ ent and textured yarns have been compared. It is observed that the yarn bulk increases while the tensile and evenness proper­ ties become inferior on' air-jet texturing. The textured yarn fabrics have lower air permeability, higher thermal resistance, higher abrasion resistance and inferior strength-related properties as compared to the parent yarn fabrics. Air-jet textured polyester/wool blend spun yarns can be used where higher comfort-related properties are desirable.

Keywords: Air-jet texturing, Fabric properties, Polyester/wool blended yarn, Textured yarn

1 Introduction Recently, some papers have been published on The term texture describes a yarn or textile appear­ air-jet texturing of cotton spun and composite yarns}·7. ance, character and hand, and relates to the composi­ Studies on ring- spun, siro- spun, rotor- spun and tion, structure or finish of the yarn or fabric I . Texture wrap- spun air-jet textured yarns have been reported. 2 is affected both by surface and internal effects . Sur­ Improvements in the bulk, warmth, handle and abra­ face texture, which governs the outer appearance and sion resistance of cotton-based air-jet textured spun hand consisting of irregularities on the face of the ma­ yarn fabric indicate that simi lar im provements are terial, creates the aesthetic appeal of the end product. likely in case of air-jet textured blended worsted yarn The internal texture is determined by the relative posi­ fabrics. The yarn characteristics are also likely to be tioning of the fibres , which affects the bulk of the better because of the expected improved texturizabil­ material, i.e. the amount of air trapped between the ity due to the longer fibre length in bl ended worsted fibre s, and thus adds to the comfort and feel of the yarns. product. In the present work, air-jet texturing of polyes­ ter/wool blended worsted yarns has been carried out In general, yarn texturing is described as a tech­ and woven and knitted fabrics have been produced nique by which closely packed parallel arrangements using these yarns. Properties of the yarns and of the of continuous filaments are changed into more ran­ fabrics produced from parent and air-j et textured dom and voluminous arrangement to increase the us­ yarns have also been compared. ability of the filament yarns. Air-jet texturing is one of the several processes which are used to convert 2 Materials and Methods continuous filament yarns to textured yarns and is the Polyester/wool yarn of 25.3 tex linear density with most versatile of all the known tex turing methods. It a blend composition of 70% polyester and 30% wool is a unique and purely mechanical method which uses was used as the parent yarn. The air-jet texturing was cold supersonic air-stream to produce entan­ carried on Eltex AT/HS air-jet texturi ng machine at gled- fil ament bulked yarns of low extensibility. 300 m/min using HemaJet with TlOO core, 5 mm baf­ Air-jet texturing is a mechanical method and, there­ fle setting, 8% overfeed and 6 bar air pressure. Tex­ fore, thermoplastic and non-thermoplastic fi lament tured and parent yarns were wound onto packages at 4 yarns as well as the spun yarns can be used for air-jet cN tension for bulk measurement. Wetting of yarn texturing. before feeding to texturing unit an d mechanical stretch were not used . "To whom all the correspondence should be addressed. Phone: 659 1407; Fax: 0091-011-6862037; The parent yarn was tested for lin ear density, twi st Emai l: [email protected] level, tensile properties, unevenness an d yarn imper- KOTHARI & BAR I: PROPERTIES OF POL YESTER/WOOL YARNS AND THEIR FABRICS IS7 fections. The textured yarns were tested for linear Warp 100% Cotton 2/110s Ne (2/S .37 tex) density, physical bulk, instability, tensile properties, Weft (i) Parent yarn-2S.3 tex unevenness and yarn imperfections using the instru­ polyester/wool ments/methods listed below: (ii) Textured yarn -26.2 tex polyester/wool Parameter InstrumentIMethod End density 64 endslin. (2S.2 ends/cm) Pick density 48 picks/in. (18.9 picks/cm) Yarn twist Eureka twist tester Linear density Wrap reel and electronic Circular (tubular) weft knitted fabrics were al so weighing balance produced using both the parent and textured yarns on Tensile properties Instron tensile tester Krenzler sample knitting machine with one feeder as Unevenness/ imperfections Uster Tester -I per the following details: Physical bulk DuPont method Instability DuPont method Machine gauge 18 Cylinder diameter 3.S in . (8.9 cm) For finding yarn twist, ten specimens (10 in. each) Number of needles 198 were detwisted and twisted in the opposite direction Cylinder rpm 3S0 till the same tension as of the initial yarn builds up in the yarn to obtain the twist per inch. For finding linear The woven fabrics were used for testing in grey density, ten 100m leas were prepared on a wrap reel state and the knitted fabrics were used after dry re­ laxation. Different tests on fabrics were carried for and the yarn tex was obtained by weighing these wrap using the instruments listed below: reels on an electronic balance. The tensile properties of yarns were obtained on lnstron tensile tester Parameter Instrument (Model 4302) with a constant rate of extension ad­ justed to give 20 ±) s time to break. The gauge length Thickness and Essdiel thickness tester was kept at SOO mm and SS readings were taken to compression calculate the average values of tensile properties. The Fabric weight Electronic weighing balance yarn unevenness and imperfections were obtained on Tensile properties In stron tensile tester Uster evenness tester (UT-I) at a speed of SO m/min Bursting strength Eureka bursting strength for S min. Four readings were used to obtain CY% tester and Instron tensile and yarn imperfections per 1000 m. The physical bulk tester of the textured yarns was obtained by winding 4S00 m Abrasion resistance CSI stoll universal of parent and textured yarns on cylindrical bobbins of (Flat) abrasion tester known weight and diameter at a tension of 4 cN. The Air permeability Textech air permeability diameters and weights of the wound packages were tester measured and the package densities were calculated. Crease recovery Shirley crease recovery The physical bulk was obtained as the ratio of the tester parent yarn package density to the textured yarn Thermal resistance Tog meter package density, expressed as a percentage. For insta­ bility measurement, the yarns were hung vertically The fabric thickness was measured at a pressure of with a pretension of 0.09 gfltex and one metre yarn 20 gf/m2 and the compressional resilience was ob­ length was marked. The yarn tension was increased to tained by applying the increasing and decreasing pres­ 4.S gfltex for 30s and then allowed to recover under sures on fabrics in the range of 20-2000 gflm2 and the pretension load of 0.09 gfltex for 30s.The percent­ obtaining the fabric thickness after each increasing or age extension in one metre length was used as yarn decreasing pressure step. Compressional resilience was calculated as a ratio of area under the unloading instability (%) and the average yarn instability was thickness curve to loading thickness curve and was obtained from SO readings. expressed as a percentage. A 10cm x 10cm template Plain woven fabrics were produced on a 60 in . was used to cut samples for measuring fabric weight. wide Saurer shuttle loom using both the parent and The samples were weighed on an electronic balance textured yarns as weft as per the following details: and the average weight per unit area was calculated 158 INDIAN J. FIBRE TEXT. RES ., JUNE 2002 based on 10 readings. The tensile properties of woven yarns. The cause for lower increase in bulk as com­ fabrics were obtained on Instron tensile tester by test­ pared to that in filament yarns may be partly due to ing eight warp -way and eight weft- way ravelled fab­ the lower overfeed used and partly due to the lower ric strips of 10 in. x 2.5 in. The ravelled strips of 2 in. number of loops and higher hairiness of air-jet tex­ width with 6 in. gauge length were tested with a tured spun yarns. Instability value of 4.36% is mainly cross head speed of 300 mm/min. The bursting due to the increase in disorderliness in fibre arrange­ strength of woven fabrics was obtained on a dia­ ment which leads to reduction in inter-fibre friction . phragm bursting tester and average was obtained Fig. 1 compares the stress-strain curves for parent based on five test results. For obtaining bursting and air-jet textured yarns. Both the yarns show an ini­ strength of knitted fabrics, a rod with spherical end tial elastically deformable region and, following the was attached to the load cell and a hollow cylinder yield point, a wide region of plastic deformation. The with a circular collar top clamp to clamp the fabric reduction in tenacity, breaking extension and modulus was fixed on the Instron frame. The spherical end rod in case of air-jet textured yarn is clearly reflected in was lowered on the fabric at a rate of 100 mm/min the curve for air-jet textured yarn. The cause for these and the load at which the fabric ruptures was re­ changes is the disorderliness of fibre arrangement due corded. Ten readings were used to obtain the bursting to the air-jet texturing process. strength of knitted fabrics. The flat abrasion resistance of fabrics was measured on CSI Stoll universal abra­ Table 1:"- Properties of parent and tex tured yarns sion tester with 0.5 Ib head load in case of woven fab­ Property Parent yarn Textured yarn rics and 1.0 Ib head load in case of knitted fabrics Linear density, tex 25.3 26.2 with a zero grade emery paper as abrading surface. Yarn twist, tpi 15.0 The number of abrasion cycles were read after an Physical bulk , % 100 144 electrical contact stops the machine and abrasion cre­ Instability, % 4.36 ates a hole in the fabric. Five readings were taken to Tenacity, cN/tex 18.35 9.58 obtain the average number of abrasion cycles required Breaking extension, % 24.42 19.77 Modulus, cN/tex 250.4 127.9 to abrade a fabric. Ten readings of the air flow rate Uster CY % 17 .6 1 22.48 per unit area under a pressure drop equal to the pres­ sure of I cm of water head was measured on Textech Yarn imperfections 1l000m air permeability tester to obtain the average air per­ Thin places (-50%) 31 258 meability of fabrics. Crease recovery was measured Thick places (+50%) 13 123 Neps (+200%) 14 178 using 20 samples (each of 2 in. x 1 in.) taken at ran­ dom in warp and weft directions using Shirley crease 20 recovery tester. The folded samples were loaded un­ der a 2 kg load for I min and then all owed to recover Por~nt for I min. on the dial used to measure the crease re­ covery angle. Thermal resistance was measured on a 15 tog meter in which the fabric is kept in series with a standard thermal resistance and heat is allowed to flow perpendicular to both till a steady state is ob­ tained. The temperature drop across the standard re­ . Tf"xlured sistance and the fabric sample is measured using thermocouples and the thermal resistance of fabric is calculated as the ratio of temperature drops across fabric and standard resistance multiplied by the ther­ 5 mal resistance of standard material.

3 Results and Discussion

Table 1 shows the properties of parent and air-jet <--_--:-_ _ _ .l _ _ -lI __....,L1 ----:: -'::-1-----:"1 textured yarns. The increase in bulk by 44% through 5 10 1S 20 25 30 air-jet texturing is much lower as compared to the Strain,% bulk increase in air-jet texturing of multifilament Fig. I-SlI'ess-strain curves of parent and air-jet textured yarns KOTHARI & BARI: PROPERTIES OF POL YESTERIWOOL YARNS AND THEIR FABRICS 159

The nep level, thick places and thin places increase and compressional recovery behaviour of woven and due to air-jet texturing. This affects the unevenness of knitted fabrics respectively. The bulk of the yarn the yarn and increases the Uster CV%. causes the higher thickness for textured yarn fabrics. Table 2 shows the properties of plain woven fabrics While there is a very little change in compressional produced using parent and textured yarns in weft and resilience in case of woven parent and textured yarn Table 3 shows the properties of plain knitted fabrics fabrics, there is a substantial change in compressional produced using parent and textured yarns. The in­ resilience of knitted parent and textured yarn fabrics. crease in textured yarn fabric weight, compared to The textured yarn leads to higher crease recovery that of parent yarn fabric, is due to the increased lin­ and bending modulus in case of woven fabric. The ear density of weft yarn in case of woven fabric and bursting strength in case of woven fabrics is lower for the increased linear density of feeder yarn in case of

1.0 ". " knitted fabric. Figs 2(a) and 2(b) show the thickness (a) -Parent yarn fabric O,S ---- T~xtured yo,,, rob ric 0.6 Table 2-Properties or woven fabrics produced using parent and textured yarns as weft 0.( ~ Property Parent yarn Textured yarn % Change ~ 0.2 fabric fabric .,~ 0 .- ' , , ~ 1·0 Fabric weight. g/m2 79.2 82.2 +3.79 (b) ~0.8 Fabric thickness. mm 0.32 0.34 +6.25 '\ 0.6 Compressional 87.1 87 .8 +0.80 \, resilience. % " \ , , ~ ------_.- ~ ---..0 ~- Crease recovery. deg. 0.2 o Warp 103 117 + 13.59 o (00 800 1200 1600 2000 Weft 116 132 2 +13.79 Pressure. gf/em Bursting strength. 6.4 6.0 -6.25 kglcm2 Fig. 2-Thickness and compression-recovery behaviour of (a) Abrasion resistance. 43 62 +44.19 woven fabrics. and (b) knitted fabrics no. of cycles

Breaking load. N 0.50 Warp 233.9 232.9 -0.43 Weft 466.8 287.2 - 38.47

Breaking extension. % 0·40 Warp 16.78 18.51 +10.31 Weft 32.37 27 .62 - 14.67 Air permeability. 3020 2400 -20.53 l/m2/s Thermal resistance. 0.30 0.1115 0.1193 +7.00 '- 2 ,,- K m /W ~ ",/ \ u \ , PQr~nt ro / \ Table 3 - Properties of knitted fabrics produced using parent and o (w~rt I ...J // \ textured yarns 0·20 / T~x'ur~d / t weft) Property Parent yarn Textured yarn % Change fabric fabric Fabric weight. g/m2 95.6 99.1 +3.66 0.10 Fabric thickness. mm 0.60 0.81 + 35.00 Compressional 87.4 82.8 -5.26 resi lience. % Bursting strength . kg 39.0 27 .9 - 28.46 Abrasion resi stance. 125 148 + 18.40 20 30 40 50 no. of cycle s 60 2 Elongation.mm Air permeability. l/m /s 3060 2720 - 11.11 Thermal resistance. 0.1017 0.2166 + 11 2.98 2 Fig. 3- Load-elongation behaviour of parent and textured yarn K m /W woven fabrics in warp and weft directions 160 INDIAN J. FIBRE TEXT. RES., JUNE 2002

textured sample when measured on Eureka bursting 4 Conclusions strength tester. A similar trend was observed when the Air-jet texturing improves the bulk and linear den­ knitted fabrics were tested on Instron tensile tester sity of polyester/wool blended spun yarns. The physi­ with bursting attachment for bursting strength. The cal bulk of the textured yarn increases by 44%, but the textured yarn samples show higher abrasion resistance yarn instability also increases. On air-jet texturing, the as compared to parent yarn samples. This is possibly tensile strength decreases significantly and the un­ due to the higher mobility of the surface structure of evenness of the yarn increases. There is a loss of the air-jet textured yarn. strength but abrasion resistance improves in case of Fig. 3 shows the load-elongation curves for both both woven and knitted air-jet textured yarn fabrics parent and air-jet textured yarn fabrics in warp and when compared with the parent yarn fabrics. The tex­ weft directions. The load-elongation curves for sam­ tured yarn fabrics have higher thickness and lower air ples in their warp direction do not vary much due to permeability. The knitted fabrics show better comfort­ the same warp threads in both the fabrics. But dis­ and warmth-related properties then the woven fabrics. tinctly different curves were obtained in weft direc·­ tion in case of fabrics with parent and textured yarns. References The decrease in breaking load and breaking elonga­ I Wingat I B, Fairchild's Dictionary oj Textiles, 6 th edn (Fair­ tion can be observed from the curves. The decrease in child Publications Inc., New York), 1988,614 . textured yarn strength is reflected in the strength of 2 Acar M, Basic principles of air-jet texturing and min­ textured yarn fabric samples. gling/interlacing processes, in Proceedings, Int. Calif. all The increase in cover when the textured yarns are Air-jet Texturing and Mingling/Interlacing (Loughborough University of Technology, Loughborough), 1989. used decreases the air permeability of textured yarn 3 Kothari V K, Sengupta A K, Srinivasan J & Goswami B C, fabric samples. The knitted structures have higher air Text Res J, 59(5) (1989) 292-299. permeability compared to woven structures. The 4 Srinivasan J. Seng upta A K & Kothari V K. Text Res J, 62 ( I) thermal resistance for knitted textured samples in­ (1992) 40-43. creases, while the change is much less in case of 5 Srinivasan J, Sengupta A K & Kothari V K, Text Res J, 62 (3) woven fabrics. The bulkier textured yarn in knitted (1992) 169-174. 6 Sengupta A K, Kothari V K & Srinivasan J, Text Res J, 61 (2) sample causes higher thermal resistance as compared (1991) 729-735. to that in woven samples where the textured yarn has 7 Sengupta A K, Kothari V K & Srinivasan 1, Melliand Texlil­ been used only in weft direction. ber, 72 (6) (1991) 409-412, EI64-EI65.