Indian Journal of Fibre & Textile Research Vol 29, December 2004, pp. 436-439

Characteristics of dref-3 yams with jute in core

S Mukherjeea & P K Maj umdarb

College of Textile Technology, Serampore 7 1 2 20 1 , India

Received 30 June 2003; revised received and accepted 3 J December 2003

The tensile properties of jute-acrylic and jute-cotton dref-3 yams with jute i n core have been studied. The tenacity of dref-3 yams was found to be lower but the strength translation efficiency of jute fibres was higher when used in the core of jute-acrylic dref-3 yam as compared to that when used in the flyer yarn structure. Stick-slip pattern of failure was observed in case of dref-3 yams, whereas catastrophic failure was observed in case of jute flyer yarn. Breaking elongation and specific work of rupture of the dref-3 yarns were higher than those of the jute flyer yam.

Keywords : Dref-3 yarn, Jute-acrylic yarn, Jute-cotton yarn, Modulus ratio, Packing coefficient, Stick-slip pattern, Tensile properties

IPC Code: Int. C17• DOl H 1 3/26, D020 3/00, D06H 3/00, OO I N 33/36

1 Introduction Stronger and longer fibres in the core produce Dref-3 friction spinning technology has established stronger yarns; higher core/sheath ratio gives better

its commercial success in the coarse and medium strength, whereas lower core/sheath ratio gives better count range. The yam consists of a core made of cover. Jute blended dref-3 yam is being used as weft bundle of staple parallel fibres and a sheath where the on various looms to produce denim and Oxford staple fibres are regularly twisted in a helical fashion fabrics. Dusting of jute blended dref-3 yam on around the core. The strength of such a structure is shuttleless looms is appreciably lower as compared to largely dependent on the magnitude of radial pressure similar yam spun through the other spinning systems exerted by the sheath fibres on the core fibres. due to the presence of lesser jute fibres on the surface

Although considerable research work has been even when the jute content is around 53%. Oxford carried out to study the viability of spinning different fabric with specialty finish is found to be quite fibres into yarn by this systeml-7 of spinning, very comfortable and almost free from any pricking little published work 8- 10 is available on the use of jute sensation. fibres and no published work is available on the use As reported in the work carried out at Arvind Mills, of jute fibres in the core. Due to some inherent nature the payback period I I is 4.5 years for a cotton/polyester of jute fibre, blending of jute with finer and flexible mill which has to procure jute slivers from jute mills. fibres helps to improve the processing and The payback period is 6.6 years for a new dref-3 characteristics8 of dref-2 yarns. Jute fibre has been spinning plant which has to procure all the slivers used as sheath fibre in blends with other fibres in from cotton/polyester/jute mills. dref-3 system so as to cover it with high value fibre9• In the present work, the yarns have been spun by There is a good effect lO of stronger and longer j ute dref-3 spinning system using jute fibres in the core fibres in higher percentage, either in the core or in the and acrylic as well as cotton as sheath fibres and the sheath, on the tensile properties of dref-3 yarn. tensile characteristics of these yarns have been

Dref-3 yarn with jute in the intermediate layer is compared with those of conventional jute flyer yarns. quite strong and has significantly lower shedding tendency during subsequent high speed weavingl l . 2 Materials and Methods

2.1 Materials

apresent address : MPMMC Division, Indian Jute Industries' Research Association, 17 Taratola Road, Kolkata 700 088, India �o whom all the correspondence should IX: addressed. Phone : 2662 1 058 ; Fax : + 9 1 - 33 -2662 1 058; E-mail : pkm5 @rediffmail.com

Jute fibres of Tossa-Daisee grade(TD-3), acrylic staple fibres of 3 denier and 5 1 mm length and cotton fibres of Digvijay grade were used. Some of the physical properties of these fibres are given in Table ! .

MUKHERJEE & MAJUMDAR: DREF-3 YARNS WITH JUTE IN CORE 437

2.2 Methods 2.2.1 Preparation of Yarn Samples

A twenty-spindle Mackie apron-draft spinning frame was used to spin the conventional jute yams of nominal l inear density ( 1 75 tex) with four different twist multipliers (24.35, 25 .56, 26.83 and 28.3) at a flyer speed of 3200 rpm.

Dref-3 machine was used to spin jute-acrylic and jute-cotton yams of same nominal l inear density at a delivery speed of 75 m/min . The speeds of spinning and carding drums were maintained at 3750 and 1 2000 rpm respectively. While jute sliver of 3 . 1 ktex was fed to the drafting unit 1 , five slivers each of 3 .2 ktex were fed to the drafting unit I I in preparing both jute-acrylic and jute-cotton yarns. Core-sheath ratio of 70:30 was maintained to achieve stable spinning condition.

2.2.2 Evaluation of Tensile Properties

Tensile characteristics of all the fibres were tested on Zwick tensile tester (Model 1 445) with a gauge length of 1 0 mm. Average values of tenacity, breaking elongation and initial modulus were taken for each type of fibres. Tests were carried out with cross - head speeds of 1 , 5 and 1 0 mm/min for jute, cotton and acrylic fibres respectively.

Tensile characteristics of the yam samples were tested on Instron tensile strength tester (Model 1 195) with the gauge length of 500 mm and cross-head speed of 50 mm/min in all the cases. The average values of fifty tests were taken for each yarn sample to evaluate tenacity, elongation, specific work of rupture and initial modulus.

2.2.3 Evaluation of Packing CoefflCient

The packing coefficient of each type of yam was computed from the ratio of bulk densities of yarn and fibre. The diameter of yam samples was measured on ' a projectina microscope with the magnification of X 20 . A pre-tension level of 0.025 cN/tex was used for each yam sample. An average of thirty readings was taken for each yarn sample. Specific volume of fibre (Vr) in case of dref-3 yams was calculated by taking the weighted average of specific volumes of the two component fibres using the following relationship :

Specific volume of fibre ( Vr) = ------XVt2 + YVfJ

where Vr \ and Vf2 are the specific volumes of fibres f\ and f2; and X and Y, the fractional presence of fibres f\

and f2 , Specific volumes of jute, acrylic and cotton fibres were taken as 0.7, 0.85 and 0.65 cc/g respectively.

3 Results and Discussion 3.1 Tensile Characteristics of Jute Flyer Yarns

The twist-tenacity relationship is shown in Fig. 1 .The optimum tenacity value is observed at a twist multiplier of 25.56. The increase in strength at low twist level is due to the increase in cohesive force and fall in strength after optimum twist multiplier is due to the obliquity effect.

3.2 Tensile Characteristics of Jute Blended Dref-3 Yarns 3.2.1 Tenacity

The characteristics of jute, acrylic and cotton fibres are shown in Table 1 . Much lower value for elongation is observed in case of cotton fibres when compared with the normal values. This may be due to the short and coarser variety as lower elongation values are generally observed \2 in shorter and coarser varieties.

The tensile characteristics of jute-acrylic and jute­cotton dref-3 yams are given in Table 2 along with the tensile characteristics of jute flyer yam at the optimum twist multiplier of 25.56. Tenacity values of both jute-acrylic and jute-cotton dref-3 yarns are found to be lower as compared to that of jute flyer­spun yarn. Jute flyer yam shows the highest and jute­cotton dref-3 yam shows the lowest tenacity values

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1 1 .4 1 1 .2 1 1

� 10.8 <oj '" � 1 0.6 J.. ... m � 10.4 .y <I.l 0-m 10.2

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Twist multiplier, turns/em x {tex Fig. 1 - Effect of twist multiplier on tenacity of twisted jute yam

438 INDIAN J. FIBRE TEXT. RES., DECEMBER 2004

while jute-acrylic dref-3 yarn occupies the intermediate position. However, the tenacity of jute­acrylic dref-3 yarn is found to have higher value than that of jute flyer yarn when the tenacity is calculated on the basis of l inear density of jute fibres at the core. This indicates higher strength translation efficiency of jute fibres at the core. Tenacity of jute-cotton dref-3 yarn is found to be stil l lower than that of jute flyer yam even when calculated on the same basis. It is evident from these results that the transverse pressure developed by surface acrylic fibres on the core structure comprising the jute fibres is more during straining of the yarn as compared to that developed by the twisted structure in case of jute flyer yarn. The transverse pressure generated by the surface cotton fibres is lower than that generated by the acrylic fibres. The less initial transverse pressure provided by cotton sheath is also evident from the lower packing coefficient value (Table 2). A marginally lower packing coefficent value of jute- acrylic dref-3 yarn is observed as compared to that of jute flyer yarn.

3.2.2 IniJial Modulus

The initial modulus values of both jute-acrylic and jute-cotton dref-3 yarns are lower than that of jute flyer yam. But considering the l inear density of jute

Table l -Characteristics of fibres

Characteristic Jute Acrylic Cotton

Linear density, tex 3. 1 1 0.333 0. 1 7

Tenacity, cN / tex 47.53 26.36 3 1 .68

Elongation, % 2.84 32.37 2.7 1

Initial modulus, cN / tex 1 558.6 503 1 237. 1

fibres in the core, the initial modulus is found to be higher for both jute-acrylic and jute-cotton dref-3 yams. Table 2 also shows the ratio of yarn modulus and fibre Uute) modulus. The ratio is lower in case of dref-3 yarns than that in case of jute flyer yarn when the count of the whole yam is considered. But when linear density of jute fibres in the core is considered, both jute-acrylic and jute-cotton dref-3 yarns show higher values of modulus ratio than that of jute flyer yam. This essentially shows higher effective utilization of fibre tensile characteristics in the elastic deformation part of dref-3 yam due to the development of more transverse pressure on the core structure by the surface fibres.

3.2.3 Elongation and Specific Work of Rupture

Elongation at maximum load for the dref-3 yarns is found to be higher than the elongation at failure of the jute flyer yarn. This may be due to the slipping and gripping phenomenon of the dref-3 yarns, thus delaying the failure to occur, as compared to the catastrophic failure in case of jute flyer yarn. Specific work of rupture values of dref-3 yarn are found to be remarkably higher than that of jute flyer yarn, which is due to the step-wise failure of the dref-3 yarns, resulting in the failure to occur over a longer time as compared to the catastrophic failure of jute flyer yarn.

3.3 Failure Mechanism

The failure mechanism of jute flyer yam and jute­acrylic and jute-cotton dref-3 yarns can be explained from their stress-strain curves (Fig. 2). As compared to the catastrophic failure in case of jute flyer yarn, a stick-slip pattern due to the alternate slipping and

Characteristic

Table 2 - Tensile characteristics of yarns

Flyer-spun jute yam Dref-3 spun yarn

Jute-acrylic Jute-colton

Linear density, tex 173 1 82 1 82

Tenacity considering whole yarn, eN/tex 1 1 .29 8.5 1 7.53

Tenacity considering core fibres, cN / tex 12 . 1 6 1 0.76

Elongation, % 1 . 2 1 1 .97 1 1 .56

Specific work of rupture, mJ/tex - m 0.78 1 .3 1 1 . 10

Initial modulus considering whole yam, cN / tex 940.5 800.4 778.5

Initial modulus considering core fibres, cN / tex 1 143.4 1 1 1 2. 1

Modulus ratio considering whole yam 0.60 0.5 1 0.50

Modulus ratio considering core fibres 0.73 0.7 1

Packing coefficient 0.49 0.47 0.42

Modulus ratio=Yam modulus/Jute fibre modulus

M UKHERJEE & MAJUMDAR: DREF-3 YARNS WITH JUTE TN CORE 439

12 r---------------------------------�

10

>o! 8 .. � '"' ;i '" 6 ... � '"' I::: 'u OJ c.. 4 V)

2

0 2

Flyer,spun jute yarn

Dref-3 spun jute acrylic yarn

Dref-3 spun jute cotton yarn

4 Elongation , %

6

Fig. 2 - Stress-strain curves of flyer-spun jute and dref-3 spun jute-acrylic and jute-cotton yarns

gripping of core and sheath fibres is observed in case of dref-3 yarns. A phenomenon of mUltiple breakage of core fibres is possibly the reason of such behaviour for dref-3 yarns, which is due to the continual development of transverse pressure by the sheath fibres as the yarn is strained.

4 Conclusions 4.1 Jute can be used successfully in the core of

dref-3 friction yarn. Core-sheath ratio of 70 : 30 for both jute-cotton and jute-acrylic is found to be the most suitable from the spinning point of view. Maximum speed of 75 mlmin is also found to be possible for stable spinning.

4.2 Jute-acrylic and jute-cotton dref-3 yarns with jute in the core show considerable strength but lower than that of jute flyer yarns. The strength translation efficiency of the jute fibres in the core is higher for jute-acrylic dref-3 yarns than for the corresponding flyer yarn.

4.3 The elongation at maximum load for jute­acrylic and jute-cotton dref-3 yarns i s h igher than

the breaking elongation of j ute flyer yarn , resulting in higher specific work of rupture of these yarns. The i nitial modulus of jute-acrylic and jute-cotton dref-3 spun yarns is comparable with that of jute flyer yarn .

4.4 The spinning of jute-cotton and jute-acrylic dref-3 yarn and making fabrics from such yarns shall be commercially viable and can be used for the production of diversified value-added products, l ike furnishings, decorative fabrics and blankets.

Acknowledgement One of the authors (S M) is grateful to the Director,

Indian Jute Industries' Research Association, Kolkata, for granting study leave and extending support to complete the work.

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