Changes in Molecular Size and Size Distribution and Their Effects on Mechanical Properties of Nylon-6 Yarns During Texturizing

Abstract

The changes in average intrinsic viscosity and its distribution and their effect on mechanical properties of nylon-6 (poly caprolactam) multifilament yarn during texturizing were studied. It was found that change in average intrinsic viscosity is not the only indicator of the changes taking place in the, mechanical properties of the yarn. The changes in the molecular size distribution, on the other hand, can be regarded as a better indicator in this regard. The reduction in the breaking stress of the textured yarn is dependent on texturizing variables— e.g. : heater temperature, contact time twist, inherent moisture content of the feed yarn, yarn tension in the texturizing zone, etc. The elongation percentage at break, on the other hand, may either decrease or increase. The changes have been found to be dependent on the changes in the low molecular weight, high molecular weight species and broadness of the distribution curve.