Indian Journal of Fibre & Textile Research Vol. 25, June 2000, pp. 92-96

A study on wrap-spun jute yarn with cellulosic yarn as wrapping element

A N Roy, G Basu & A Majurnder

National Institute of Research on Jute and Allied Fibre Technology, 1 2 Regent Park, Calcutta 700 040, India

Received 26 March 1999; revised received and accepted 4 August 1999

Using the hollow-spindle technology, the wrap-spun jute yarns having linear densities of 276, 1 90 and 1 20 tex and varying wrap density (250-450 wraps/m) were produced with 2-ply cotton as wrapping yarn. Wrap-spun jute yarn of 276 tex was also spun using viscose rayon multifilament as wrapping yarn. The yarns with 450 wraps/m could not be spun due to excessive breakage in case of 276 tex linear density. Tensile strength of 276 tex and 1 90 tex wrap-spun jute yarn decreased with the increase in wraps/m. However, for finer yarns of 1 20 tex, the trend was erratic. The load-elongation curves of wrap­spun jute yarns having higher wrap densities manifested staggered multi-peak type fracture whereas the rupture was catastrophic (uni-pick type) when the wrap density was lower. The breaking elongation of all the yarns generally increased with the increase in wrap density. Wrap-spun jute yarns were comparatively better in appearance than the conventional all­jute yarns.

Keywords: Cotton yarn, Jute yarn, Tensile properties, Viscose rayon multifilament yarn, Wrap-spun yarn

1 Introduction In an effort to produce wrap-spun jute yarn using

hollow spindle technique, Xie et at. J proposed a general model to predict the yarn strength from different structural parameters of wrap-spun yarn and confirmed their theoretical approach through experimental work2,) on wrap-spun woollen yarn with nylon filament as wrapping element. Behery and Nunes4 studied the effect of wrapping element, linear density and wrap density on wrap-spun polyester yarn structure and tenacity. Several researchers5.9 have reported about the various properties of wrap-spun jute yarns by adopting hollow-spindle technology. Most of them, however, spun the yarns with synthetic multifilament or monofilament yarns as wrapping element, restricting the wrap density to the maximum of 300 wraps/m. Jute fibre core - synthetic filament wrapping yarn combination requires separate treatments during chemical processing, e.g. bleaching, dyeing, etc. for jute and synthetic components, Moreover, these yarns are not fully bio-degradable, So, with the objective to produce fully bio-degradable wrap-spun yarn, 2-ply cotton yarn was selected as wrapping element as it is compatible with the chemical nature of jute. Khatua et at.? reported some experimental work on wrap-spun jute yarn with viscose rayon multifilament yarn as wrapping element. But no report is available about wrap-spun jute yarn prepared with cotton yarn as wrapping element in hollow-spindle wrap spinning machine.

Bhattacharya and SenguptaJO reported about jute yarn wrapped with cotton yarn, spun in the conventional jute spinning machine. Jute fibres of wrap-spun jute yarn, prepared in hollow-spindle machine, were aligned parallel to yarn axis and were not subjected to twisting while the jute fibres in the spin-wrapped jute yarns, as reported by Bhattacharya and SenguptalO, were twisted as normal spun yarns and hence were helically aligned with respect to yarn axis. Hence, the structures of these two types of yarns are quite different. It was, therefore, thought worthwhile to engineer a wrap-spun jute yarn with cotton yarn as wrapping element in the high-speed hollow spindle machine at a speed 2 .5 - 3 .5 times of that of the conventional jute spinning process with an idea to improve some of the yarn tensile properties to suit weaving on modern high speed looms, These yarns, in which jute fibre being partially covered with cotton yarn, may also improve the aesthetic properties of the finished product. A systematic approach has been made in the present study to develop a wide range of wrap-spun jute yarn with cotton yam as wrapping element. The wrap-spun yarns were spun in three different linear densities (276, 190 and 1 20 tex) with varying wrap density (250 - 450 wraps/m) for each count. Two-ply cotton yarn was used as a wrapping element as it is more uniform and reasonably stronger than single yarn of the equivalent linear density, Moreover, 2-ply cotton yarn is expected to provide an aesthetic effect in the wrap-spun yarn. In addition, for

ROY et al. : STUDY ON WRAP-SPUN JUTE 93

comparisor a viscose rayon multifilament yarn was also. used as wrapping element to prepare wrap-spun jute yarn of a particular l inea� density.

2 Materials and Methods

2.1 Materials Jute fibre of commercial hessian warp batch, 2-ply

1 0 tex cotton yarn, and viscose rayon multifilament of 1 3 .3 tex ( 1 20 denier) were used.

2.2 Methods Jute yarn samples of 276, 1 90 and 1 20 tex nominal

linear densities were spun successfully on (i) Suessen Parafil 2000 wrap-spinning machine at Mis New Central Jute Mills Ltd, West Bengal, after making necessary adjustments in some of the machine parameters, and (ii) Mackie apron-draft jute sliver spinning machine available in our laboratory. All-jute yarns of three different l inear densities were also spun with optimum twist in the conventional apron draft spinning m;lchine from the conventional third drawn sliver. To prevent much loss of moisture, the drawn sliver was brought from jute mill to our laboratory in polyethylene bags. In all, eighteen different wrap­spun jute yarns having cotton/viscose rayon multifilament yarn as wrapping element were prepared, maintaining the draft and delivery speed at

40 and 60 rnlmin respectively at spinning stage. In case of wrap-spun yarn, the fibre was processed through conventional jute spinning system up to the second drawing stage. The sliver thus obtained was once again processed through the second drawing machine, keeping the doubling and draft same to get more regular sliver. Inspite of that, some variation in actual l inear density was observed in wrap-spun jute yarn having 276 tex nominal l inear density which may be due to the variation in card sliver.

The load-elongation properties of all the yarns were tested on an Instron tensile tester at 65% RH and 27°e. The gauge length and cross-head speed were kept at 500 mm and 500 mrnlmin respectively.

3 Results and Discussion The tensile properties of the wrap-spun yarns, two­

ply cotton yarn, viscose rayon multifilament yarn and conventionally spun all-jute yarns are given in Table 1 . It is observed that the wrap-spun jute yarns of all the three l inear densities have lower tenacity and higher extension-at-break than the conventional all­jute yarns of the equivalent linear densities. A similar trend was also observed by Khatua et ae. It may also be observed from Fig.l and Table 1 that the rupture process df some of the wrap-spun yarns is catastrophic, i .e. uni-peak, while that of the others manifested staggered stick-slip failure, resulting in

Table I-Tensile properties of wrap-spun jute. conventional all-jute. cotton and viscose rayon multi filament yarns

Type of yarn Wraps/m Yarn linear density. tex Wrapping Tenacity Extension Number of stress-Actual Nominal yarn cNltex % peaks during

rupture

Wrap-spun 250 256 276 Cotton 8.49 3.28

Wrap-spun 300 25 1 276 Cotton 7.89 3.34

Wrap-spun 350 252 276 Cotton 6.57 6.9 1

Wrap-spun 400 3 1 0 276 Cotton 4.98 9.7 1 3 - 1 2

Wrap-spun 250 261 276 Viscose rayon 8.33 2.98 multifilament

Wrap-spun 300 246 276 Viscose rayon 7.42 2.93 multifilament

Wrap-spun 350 332 276 Viscose rayon 4.41 5.99 2 - 6 multifilament

Wrap-spun 400 3 1 0 276 Viscose rayon 4. 1 5 6.79 2 - 9 multifilament

Wrap-spun 250 1 86 190 Cotton 9. 1 8 2.57

Wrap-spun 300 1 82 1 90 Cotton 7.79 4.88

Wrap-spun 350 1 88 1 90 Cotton 6.72 7.58 2 - 8

Wrap-spun 400 1 9 1 1 90 Cotton 6.45 6.3 1 I - 7

Wrap-spun 450 198 190 Cotton 6.30 7 . 1 4 I - I I Wrap-spun 250 1 1 9 1 20 Cotton 7.46 2.36

Contd

94 iNDIAN 1. FIBRE TEXT. RES. , JUNE 2000

Table I -Tensile properties of wrap-spun jute, conventional all-jute, cotton and viscose rayon multitl lament yarns-Contd

Type of yarn Wraps/m Yarn linear density, tex Wrapping Tenacity Extension Number of stress-Actual Nominal yarn cN/tex % peaks during

Wrap-spun 300 I I I 1 20

Wrap-spun 350 1 1 5 1 20

Wrap-spun 400 1 23 1 20

Wrap-spun 450 1 1 6 1 20

Conventional 1 60" 293 276

Conventional 200· 2 1 8 1 90

Conventional 240· 1 38 1 20

Two-ply Cotton 1 0.2x2 1 0 x 2

Viscose rayon 1 3 .33 1 3 .33 multifilament

"Turns per metre

several stress peaks during rupture. The stress peaks are in the ascending and descending portions of the load-elongation curves. Table I shows that for 276 tex yams, the multiple breaks are at wrap density of 400 wraps/m. Beyond this wrap density level, the yam could not be spun due to the excessive breakage of the wrapping yam, i .e . cotton yam. The low breaking energy of the cotton yam as compared to that of the filament yam is the prime factor for staggered breaks of the aforesaid wrap-spun jute yams. The increase in wrap density, though increased the lateral pressure and hence the inter-fibre cohesion of jute fibre, brought about simultaneous increase in the strain level of the wrapping cotton yam. Beyond the wrap density of 400 wraps/m, for coarser yam of 276 tex nominal count , the dynamic strain level was so high that the wrapping cotton yam ruptured during spinning and consequently the yams with higher wrap density could not be spun. But for the finer yams of 1 90 tex and 1 20 tex nominal count, the wrapping cotton yams did not attain the dynamic critical strain level during spinning as the diameter of the jute core component was smaller, thereby making it possible to spin wrap­spun yams of higher wrap density (450 wraps/m) . However, during tensile testing, these yarns experienced static tensile stress. The tensile stress along yarn axis brought about both col lapse and extension of helically wound wrapping yarn. With the collapse of helical configuration of wrapping yarn, the lateral pressure increased but low extensibil i ty of cotton yarn did not permit the wrapping yarn to share the tensile stress built up in the yarn matrix. As a result, poor elongation balance occurred and the yarns ruptured. This effect became more prominent when the wrap density was increased. C0Dsequently, the

Cotton Cotton Cotton Cotton

14

12

1 0 z C 8 � 0

6 oJ 4

2

0 0

.' .....

9.46

6.96

6.73

7.40

1 1 .7 1

1 0.85

9 . 1 7

1 5 . 1 5

1 4.70 .

5 .5

7.93

7.89

6.74

1 .79

2.2

1 .7 1

6.4

1 7.62

A- 350 WPM

rupture

I - 6

I - 8

1 - 6

/:/ I -300 WPM

0 //0/// 1

2 4 6 8 1 0

ELONGATION, %

Fig. I -Load-elongation curves of 1 90 tex warp-spun jute yams with cotton yam as wrapping element

A similar trend was also observed with viscose rayon multifilament yam used as wrapping element in the wrap-spun jute yams (Table I ). However, it is worth noting that the load-elongation behaviour of the viscose rayon multifilament wrapping yarn is very much different from that of the cotton wrapping yarn (Fig. 2). The viscose rayon multifilament yarn exhibited asymmetric stretching of its filaments, resulting a pronounced yield point at a load level of around 90g and step-wise stick-slip rupture of filament during tensile failure. Accordingly, when the viscose rayon multifilament wrapped jute yarn was extended during tensile deformation, the lateral force exerted by the wrapping element suddenly dropped at the yield point. Beyond the yieid point, the 'Nrapping element did not contribute any lateral force but the parallel-laid jute staple fibres, which comprised the

ROY et al.: STUDY ON WRAP-SPUN JUTE 95

core component of the wrap-spun jute yam, started slipping. Due to the increase in fibre slippage of the core component the wrap-spun jute yam failed. Thus, although the viscose rayon multifilament wrapping yam exhibited high elongation of 1 7 .5%, it failed to contribute during building up lateral force at higher level of extension of the wrap-spun yam. The drastic drop in tenacity of the wrap-spun yarn with the increase in wrap density beyond 300 wraps/m might be explained in the light of quick attainment of the yield point of the viscose rayon multifilament yam at 350 wraps/m as the wrapping element had already

:::f/ z u

200

C 1 50

� ..J 1 00

50 Viscose multifilament

5 1 0 1 5

ELONGATION, % 20

Fig. 2-Load-elongation curves of cotton yarn and viscose multifilament yarn

attained higher level of tensile strain during spinning wrap-spun yarn of higher wrap density. Khatua et al.7 also found that with the increase in wrap density the tensile strength of wrap-spun jute yam with viscose rayon multifilament wrapping yam decreased. However, for finer yams of 1 20 tex nominal count, the trend was rath�r erratic . This might be due to the higher irregularity of the finer jute component. The breaking elongation of these yams generally increased with the increase in wrap density. However, there was a quantum jump in the breaking elongation at 350 wraps/m for 276 tex yam, as compared to those at)OO wraps/m for 1 90 and 1 20 tex yams. It was further observed that fqr finer yams, the trend of increase in breaking elongation with the increase in wrap density was not as smooth as that for coarser yams of 276 tex nominal l inear density.

Fig. 3 shows that the appearance of wrap-spun jute yam with cotton wrapping yam is comparatively better than that of the conventional all-jute yarn. This is mainly due to the less hairiness of wrap-spun jute yams as compared to that of conventionally spun yams. The decrease in hairiness of wrap-spun yam has already been reported earl ier1 1 • 1 2•

It may be mentioned here that the production speed of ) 20 tex wrap-spun jute yarn having cotton yarn as wrapping element was 60 mlmin while that of all-jute yam of equivalent l inear density was around 1 7 .5 mlmin . Besides, the spinning performance of the wrap-spun yams was quite satisfactory even with this higher delivery rate compared to that of the conventional jute yams.

Fig. 3-Photograph showing hairiness and appearance of 1 20 tex warp-spun and conventionally spun jute yarns [A-conventional al l ­jute; 8-250 wraps/m; C-300 wraps/m; D--400 wraps/m and E--450 wraps/mJ

96 INDIAN J. FIBRE TEXT. RES., JUNE 2000

4 Conclusions 4.1 Wrap-spun jute yarn generally shows lower

tenacity and higher elongation at break when compared with the conventional all-jute yarn.

4.2 Wrap-spun yarns give multi-peak breaks at higher wrap densities, depending upon the l inear density.

4.3 The tenacity of wrap-spun jute yarn with viscose rayon multifilament yarn as wrapping element is lower than that of a similar yarn having 2-ply cotton yarn as wrapping element.

4.4 The wrap-spun jute yarns are comparatively better in appearance than the conventional twisted jute yarns.

Acknowledgement The authors are thankful to Mis New Central Jute

Mills, Calcutta, for providing necessary facilities to prepare wrap-spun yarn samples.

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