Influence of core-sheath ratio and core type on DREF-III friction-spun core yarns

Abstract

DREF-III friction-spun core yarns have been produced by wrapping a fibrous sheath of viscose rayon fibres around three different polyester cores, viz. fibrous bundle, twisted fibre assembly with Z and S directions, and continuous multifilament yarn, at varying level of core-sheath ratio. It has been observed that the yarn tenacity, breaking extension and the resistance to abrasion increase with the increase in the proportion of core fibres up to 70%, irrespective of the core type, but the sheath-slipping resistance, in general, improves with the increase in sheath content. Further, Z-twisted fibrous core produces strongest yarn with comparable sheath-slipping resistance while the yarns spun with multifilament exhibit highest breaking extension and resistance to abrasion. The introduction of normal parallel fibres as core shows an increased sheath-slipping resistance for DREF-III friction-spun core yarns. Core contents as well as type of core do not show any relationship with yarn unevenness.