Properties of polyester/wool parent and air-jet textured ...nopr.niscair.res.in › bitstream › 123456789 › 22763 › 1 › IJFTR 27(2) 156-160.pdfThe textured yarn fabrics have

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

7 ( ( ~ 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 The term texture describes a yarn or textile appear-

ance, character and hand, and relates to the composi-tion, structure or finish of the yarn or fabric I . Texture is affected both by surface and internal effects2. Sur-face texture, which governs the outer appearance and hand consisting of irregularities on the face of the ma-terial, creates the aesthetic appeal of the end product. The internal texture is determined by the relative posi-tioning of the fibres , which affects the bulk of the material, i.e. the amount of air trapped between the fibres, and thus adds to the comfort and feel of the product.

In general, yarn texturing is described as a tech-nique by which closely packed parallel arrangements of continuous filaments are changed into more ran-dom and voluminous arrangement to increase the us-ability of the filament yarns. Air-jet texturing is one of the several processes which are used to convert continuous filament yarns to textured yarns and is the most versatile of all the known tex turing methods . It is a unique and purely mechanical method which uses cold supersonic air-stream to produce entan-gled-fil ament bulked yarns of low extensibility. Air-jet texturing is a mechanical method and, there-fore, thermoplastic and non-thermoplastic fi lament yarns as well as the spun yarns can be used for air-jet texturing.

"To whom all the correspondence should be add ressed. Phone: 659 1407 ; Fax: 0091-011-6862037; Emai l: [email protected]

Recently, some papers have been published on air-jet texturing of cotton spun and composite yarns}·7. Studies on ring- spun, siro- spun, rotor- spun and wrap- spun air-jet textured yarns have been reported . Improvements in the bulk, warmth, handle and abra-sion resistance of cotton-based air-jet textured spun yarn fabric indicate that simi lar improvements are likely in case of air-jet textured blended worsted yarn fabrics. The yarn characteristics are also likely to be better because of the expected improved texturizabil-ity due to the longer fibre length in blended worsted yarns.

In the present work, air-jet texturing of polyes-ter/wool blended worsted yarns has been carried out and woven and knitted fabrics have been produced using these yarns. Properties of the yarns and of the fabrics produced from parent and air-jet textured yarns have also been compared.

2 Materials and Methods Polyester/wool yarn of 25.3 tex linear density with

a blend composition of 70% polyester and 30% wool was used as the parent yarn. The air-jet texturing was carried on Eltex AT/HS air-jet texturi ng machine at 300 m/min using HemaJet with TlOO core, 5 mm baf-fle setting, 8% overfeed and 6 bar air pressure. Tex-tured and parent yarns were wound onto packages at 4 cN tension for bulk measurement. Wetting of yarn before feeding to texturing unit and mechanical stretch were not used .

The parent yarn was tested for linear density, twi st level, tensile properties, unevenness and yarn imper-

KOTHARI & BAR I: PROPERTIES OF POL YESTER/WOOL YARNS AND THEIR FABRICS IS7

fections. The textured yarns were tested for linear density, physical bulk, instability, tensile properties, unevenness and yarn imperfections using the instru-ments/methods listed below:

Parameter

Yarn twist Linear density

Tensile properties Unevenness/ imperfections Physical bulk Instability

InstrumentIMethod

Eureka twist tester Wrap reel and electronic weighing balance Instron tensile tester Uster Tester -I DuPont method DuPont method

For finding yarn twist, ten specimens (10 in. each) were detwisted and twi sted in the opposite direction till the same tension as of the initial yarn builds up in the yarn to obtain the twist per inch. For finding linear density, ten 100m leas were prepared on a wrap reel and the yarn tex was obtained by weighing these wrap reels on an electronic balance. The tensile properties of yarns were obtained on lnstron tensile tester (Model 4302) with a constant rate of extension ad-justed to give 20 ±) s time to break. The gauge length was kept at SOO mm and SS readings were taken to calculate the average values of tensile properties . The yarn unevenness and imperfections were obtained on Uster evenness tester (UT-I) at a speed of SO m/min for S min. Four readings were used to obtain CY% and yarn imperfections per 1000 m. The physical bulk of the textured yarns was obtained by winding 4S00 m of parent and textured yarns on cylindrical bobbins of known weight and diameter at a tension of 4 cN. The diameters and weights of the wound packages were measured and the package den sities were calculated. The physical bulk was obtained as the ratio of the parent yarn package density to the textured yarn package density, expressed as a percentage. For insta-bility measurement, the yarns were hung vertically with a pretension of 0 .09 gfltex and one metre yarn length was marked . The yarn tension was increased to 4.S gfltex for 30s and then allowed to recover under the pretension load of 0.09 gfltex for 30s.The percent-age extension in one metre length was used as yarn instability (%) and the average yarn instability was obtained from SO readings.

Plain woven fabrics were produced on a 60 in . wide Saurer shuttle loom using both the parent and textured yarns as weft as per the following detail s:

Warp Weft

100% Cotton 2/110s Ne (2/S .37 tex) (i) Parent yarn-2S.3 tex

polyester/wool (ii) Textured yarn -26.2 tex

polyester/wool End density Pick density

64 endslin. (2S.2 ends/cm) 48 picks/in . (18.9 picks/cm)

Circular (tubular) weft knitted fabrics were al so produced using both the parent and textured yarns on Krenzler sample knitting machine with one feeder as per the following details:

Machine gauge Cylinder diameter Number of needles Cylinder rpm

18 3.S in . (8.9 cm) 198 3S0

The woven fabrics were used for testing in grey state and the knitted fabrics were used after dry re-laxation. Different tests on fabrics were carried for using the instruments listed below:

Parameter

Thickness and compression Fabric weight

Tensile properties Bursting strength

Abrasion resistance (Flat) Air permeability

Crease recovery

Thermal resistance

Instrument

Essdiel thickness tester

Electronic weighing balance Instron tensile tester Eureka bursting strength tester and Instron tensile tester CSI stoll universal abrasion tester Textech air permeability tester Shirley crease recovery tester Tog meter

The fabric thickness was measured at a pressure of 20 gf/m2 and the compress ional resilience was ob-tained by applying the increasing and decreasing pres-sures on fabrics in the range of 20-2000 gflm2 and obtaining the fabric thickness after each increasing or decreasing pressure step. Compressional resilience was calculated as a ratio of area under the unloading thickness curve to loading thickness curve and was expressed as a percentage. A 10cm x 10cm template was used to cut samples for measuring fabric weight. The samples were weighed on an electronic balance 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 fabrics were obtained on Instron tensile tester by test-ing eight warp -way and eight weft- way ravelled fab-ric strips of 10 in. x 2.5 in. The ravelled strips of 2 in. width with 6 in. gauge length were tested with a cross head speed of 300 mm/min . The bursting strength of woven fabrics was obtained on a dia-phragm bursting tester and average was obtained based on five test results. For obtaining bursting strength of knitted fabrics, a rod with spherical end was attached to the load cell and a hollow cylinder with a circu lar collar top clamp to clamp the fabric was fixed on the Instron frame. The spherical end rod was lowered on the fabric at a rate of 100 mm/min and the load at which the fabric ruptures was re-corded. Ten readings were used to obtain the bursting strength of knitted fabrics. The flat abrasion resistance of fabrics was measured on CSI Stoll universal abra-sion tester with 0.5 Ib head load in case of woven fab-rics and 1.0 Ib head load in case of knitted fabrics with a zero grade emery paper as abrading surface. The number of abrasion cycles were read after an electrical contact stops the machine and abrasion cre-ates a hole in the fabric. Five readings were taken to obtain the average number of abrasion cycles required to abrade a fabric. Ten readings of the air flow rate per unit area under a pressure drop equal to the pres-sure of I cm of water head was measured on Textech air permeability tester to obtain the average air per-meability of fabrics . Crease recovery was measured using 20 samples (each of 2 in. x 1 in.) taken at ran-dom in warp and weft directions using Shirley crease recovery tester. The folded samples were loaded un-der a 2 kg load for I min and then allowed to recover for I min. on the dial used to measure the crease re-covery angle. Thermal resistance was measured on a 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-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-mal resistance of standard material.

3 Results and Discussion Table 1 shows the properties of parent and air-jet

textured yarns. The increase in bulk by 44% through air-jet texturing is much lower as compared to the bulk increase in air-jet texturing of multifilament

yarns. The cause for lower increase in bulk as com-pared to that in filament yarns may be partly due to the lower overfeed used and partly due to the lower number of loops and higher hairiness of air-jet tex-tured spun yarns. Instability value of 4.36% is mainly due to the increase in disorderliness in fibre arrange-ment which leads to reduction in inter-fibre friction .

Fig. 1 compares the stress-strain curves for parent and air-jet textured yarns. Both the yarns show an ini-tial elastically deformable region and, following the yield point, a wide region of plastic deformation. The reduction in tenacity, breaking extension and modulus in case of air-jet textured yarn is clearly reflected in the curve for air-jet textured yarn. The cause for these changes is the disorderliness of fibre arrangement due to the air-jet texturing process.

Table 1:"- Properties of parent and textured yarns

Property Parent yarn Textured yarn

Linear density , tex 25.3 26.2 Yarn twist, tpi 15.0 Physical bulk , % 100 144 Instability, % 4.36 Tenacity, cN/tex 18.35 9.58 Breaking extension, % 24.42 19.77 Modulus, cN/tex 250.4 127.9 Uster CY % 17.6 1 22.48

Yarn imperfections 1l000m

Thin places (-50%) 31 258 Thick places (+50%) 13 123 Neps (+200%) 14 178

20

Por~nt

15

. Tf"xlured

5

KOTHARI & BARI: PROPERTIES OF POL YESTERIWOOL YARNS AND THEIR FABRICS 159

The nep level, thick places and thin places increase due to air-jet texturing . This affects the unevenness of the yarn and increases the Uster CV%.

Table 2 shows the properties of plain woven fabrics produced using parent and textured yarns in weft and Table 3 shows the properties of plain knitted fabrics produced using parent and textured yarns. The in-crease in textured yarn fabric weight, compared to that of parent yarn fabric, is due to the increased lin-ear density of weft yarn in case of woven fabric and the increased linear density of feeder yarn in case of knitted fabric. Figs 2(a) and 2(b) show the thickness

Table 2-Properties or woven fabrics produced using parent and textured yarns as weft

Property

Fabric weight. g/m2 Fabric thickness. mm Compressional

resilience. %

Crease recovery. deg.

Warp Weft

Bursting strength. kglcm2

Abrasion resistance. no. of cycles

Breaking load. N

Warp Weft

Breaking extension. %

Warp Weft

Air permeability. l/m2/s

Thermal resistance.

K m2/W

Parent yarn fabric

79.2 0.32 87.1

103 116 6.4

43

233.9 466.8

16.78 32.37 3020

0.1115

Textured yarn fabric

82.2 0.34 87.8

117 132 6.0

62

232.9 287.2

18.51 27 .62 2400

0.1193

% Change

+3.79 +6.25 +0.80

+ 13.59 +13.79 -6.25

+44.19

-0.43 - 38.47

+10.31 - 14.67 -20.53

+7.00

Table 3 - Properties of knitted fabrics produced using parent and tex tured yarns

Property Parent yarn Textured yarn % Change fabric fabric

Fabric weight. g/m2 95.6 99.1 +3.66 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

no. of cyc les Air permeability. l/m2/s 3060 2720 - 11.11 Thermal resistance. 0.1017 0.2166 + 11 2.98

K m2/W

and compressional recovery behaviour of woven and knitted fabrics respectively . The bulk of the yarn causes the higher thickness for textured yarn fabrics . While there is a very little change in compressional resilience in case of woven parent and textured yarn fabrics, there is a substantial change in compressional resilience of knitted parent and textured yarn fabrics.

The textured yarn leads to higher crease recovery and bending modulus in case of woven fabric . The bursting strength in case of woven fabrics is lower for

1.0

O,S

0.6

0.(

~ 0.2 ~ 0 ., ~ 1·0

~0.8

0.6

(a)

~

.- '

(b)

'\ \,

" , \ ,

". " -Parent yarn

---- T~xtured yo,,,

, ,

~ ~ ------------_.-0.2

o o

---..0

(00

-~

800 1200 2

Pressure. gf/em

fabric

rob ric

1600 2000

Fig. 2-Thickness and compression-recovery behaviour of (a) woven fabrics. and (b) knitted fabrics

'-

~ u ro o ...J

0.50

0·40

0.30

0·20

0.10

20

,,-",/ \ , \

/ \ // \

PQr~nt (w~rt I

/ T~x'ur~d / t weft)

30 40 50

Elongation.mm 60

Fig. 3- Load-elongation behaviour of parent and textured ya rn woven fabrics in warp and weft directions

160 INDIAN J . FIBRE TEXT. RES ., JUNE 2002

textured sample when measured on Eureka bursting strength tester. A similar trend was observed when the knitted fabrics were tested on Instron tensile tester with bursting attachment for bursting strength . The textured yarn samples show higher abrasion resistance as compared to parent yarn samples. This is possibly due to the higher mobility of the surface structure of the air-jet textured yarn.

Fig. 3 shows the load-elongation curves for both parent and air-jet textured yarn fabrics in warp and weft directions. The load-elongation curves for sam-ples in their warp direction do not vary much due to the same warp threads in both the fabrics . But dis-tinctly different curves were obtained in weft direc·-tion in case of fabrics with parent and textured yarns. The decrease in breaking load and breaking elonga-tion can be observed from the curves. The decrease in textured yarn strength is reflected in the strength of textured yarn fabric samples.

The increase in cover when the textured yarns are used decreases the air permeability of textured yarn fabric samples. The knitted structures have higher air permeability compared to woven structures. The thermal resistance for knitted textured samples in-creases, while the change is much less in case of woven fabrics. The bulkier textured yarn in knitted sample causes higher thermal resistance as compared to that in woven samples where the textured yarn has been used only in weft direction .

4 Conclusions Air-jet texturing improves the bulk and linear den-

sity of polyester/wool blended spun yarns. The physi-cal bulk of the textured yarn increases by 44%, but the yarn instability also increases. On air-jet texturing, the tensile strength decreases significantly and the un-evenness of the yarn increases. There is a loss of strength but abrasion resistance improves in case of both woven and knitted air-jet textured yarn fabrics when compared with the parent yarn fabrics. The tex-tured yarn fabrics have higher thickness and lower air permeability. The knitted fabrics show better comfort-and warmth-related properties then the woven fabrics.

References I Wingat I B, Fairchild's Dictionary oj Textiles, 6 th edn (Fair-

child Publications Inc., New York) , 1988,61 4 .

2 Acar M, Basic principles of air-jet texturing and min-gling/interlacing processes, in Proceedings, Int. Calif. all Air-jet Texturing and Mingling/Interlacing (Loughborough University of Technology, Loughborough), 1989.

3 Kothari V K, Sengupta A K, Srinivasan J & Goswami B C, Text Res J, 59(5) (1989) 292-299.

4 Srinivasan J. Seng upta A K & Kothari V K. Text Res J, 62 ( I) (1992) 40-43 .

5 Srinivasan J, Sengupta A K & Kothari V K, Text Res J, 62 (3) (1992) 169-174.

6 Sengupta A K, Kothari V K & Srinivasan J, Text Res J, 61 (2) (1991) 729-735.

7 Sengupta A K, Kothari V K & Srinivasan 1, Melliand Texlil-ber, 72 (6) (1991) 409-412, EI64-EI65 .