Physical properties of Kevlar and Nomex plied and covered yarns

This article experimentally investigates various physical properties of Kevlar and Nomex plied yarns. The tensile properties of a yarn decide the performance of post spinning operations – warping, weaving and knitting – hence its accurate technical evaluation carries much importance in industrial applications. For this purpose, Nm 50 Kevlar and Nomex yarns were twisted in various combinations with a DirecTwist machine. Multi-yarn twisting and cross-yarn covering methods were used to produce plied yarns. Surface roughness (both pin friction coefficient and yarn-to-yarn friction coefficient), lint generation, hairiness, breaking force and breaking elongation properties of the yarns were tested. Furthermore, the effect of twisting technique, twist amount and yarn type on these physical properties of yarns were statistically investigated.