Chemical Texturing or Bulking of Rotor-spun Jute/Polyester-fibre Blended Yarns

Abstract

Rotor-spun jute (J) and polyester (P) blended yarns of different blend ratios were subjected to a chemical-texturing or bulking process by using caustic soda solutions of different concentrations at different temperatures. Among the various blend compositions employed, a 70:30 J/P composition produced the best bulking effect and strength retention when an 18% (w/w) NaOH solution was applied at 25°C. The bulking effect on the70:30 J/P blended rotor-spun yarn with 13% NaOH at 10°C almost equalled the effect of the 18% NaOH at 25°C. A comparative study on chemical bulking for the rotor-spun J/P blended yarns and the conventional-spun yarns revealed that the rotor-spun J/P blended yarns produced higher bulk and elongation at break, suffered less weight loss, and exhibited a higher degree of migration of the polyester component of the blend towards the yarn's surface during bulking while retaining higher tenacity, even though the overall tenacity of the rotor-spun yarn was found to be always less than that of the comparable conventional-spun yarn. Crimp so imparted in the 70:30 J/P blended yarns on chemical bulking was stable or remained undiminished over four successive soap washes. Both the crimp level and crimp stability were enhanced measurably on application of a heat-setting treatment at 180°C or by a post-treatment using different resins. Amongst the resins employed (viz., dimethylol dihydroxy ethylene urea (DMDHEU), acrylamide–formaldehyde (AMF), and butylated urea–formaldehyde (BUF) resins), DMDHEU gave the highest order of crimp stability together with a somewhat higher strength loss. However, the use of blends of DMDHEU and BUF resins in selected weight proportions imparted enhanced crimp stability together with a relatively higher order of strength retention.