Effect of thermal treatment on wrap-spun jute yarns

Abstract

Wrap-spun jute yarns prepared at hollow spindle spinning machine using polyester (PET), nylon, polypropylene (PP) flat and textured multifilament and PP monofilament yarns as wrapping elements with wrap density of 350 wraps/m were subjected to thermal treatments in dry heat and boiling water. The thermal treatment in dry heat was done for 5,10, 15 and 30 min at 185°C for PET and nylon wrapped yarns and at 135^oC for PP wrapped yarns. Boiling water treatment was carried out for 30 min. On thermal treatment, a downward trend in tenacity was observed in case of polyester, nylon and polypropylene flat multifilament wrapped yarns but no definite trend was observed in case of polypropylene textured multifilament and polypropylene monofilament wrapped yarns, while the breaking extension of all the wrap-spun yarns

increased. The work of rupture of wrap-spun yarns also decreased with the increase in treatment time on dry heating except in case of nylon wrapped yarn where the work of rupture improved remarkably up to 10 min of exposure and then again dropped. On boiling water treatment, the work of rupture of PET, ny lon and PP flat multifilament wrapped yarns increased and that of PP textured multifilament and PP monofilament wrapped yarns decreased. Initial modulus and secant modulus of all the wrap-spun yarns ,except polyester wrapped yarn , generally decreased on dry heating. Residual shrinkage of all the wrap-spun yarns decreased with the increase in treatment time in dry heat. No relationship could be established between the changes in tensile properties of wrap-spun yarns and those of synthetic wrapping yarns.