Structure-Property Relationship of Blended Cotton Yarns Made from Low and High Tenacity Fibers

Abstract

The tensile response of staple yams is usually determined by their structure and the mechanical properties of their constituent fibers. Yarn structure is influenced by the radial disposition of fibers along the yam length, commonly known as migration, and the packing density of the fibers in the yarn cross section. These, in turn, are affected by fiber properties, yarn factors, and the dynamics of preparatory and spinning pro cesses. Yarn structure development is further complicated when the yarn is spun from blends of different fiber types because the blending method usually profoundly influ ences the position and orientation of the fibers in the yam matrix. This investigation is concerned with the effect of fiber properties and yarn structure on the tensile properties of ring spun yarns made from a 50:50 blend of high (Pima) and low (Upland) tenacity cotton fibers spun using intimate and drawframe blending techniques. The drawframe blended yarn in this work is produced by arranging all high tenacity fiber slivers in the center of the drawframe creel to determine if preferential positioning in the core of the yam helps to improve the strength of drawframe blended yarn compared with intimate blended yarns. The findings reveal that intimate blended yam has better tensile strength than drawframe blended yarn, even though more high strength Pima cotton fibers are positioned in the core of the yam. This is because non-uniform fiber distribution re sulting from blending of different fibers affects the migratory behavior of fibers. The tensile failure of such yams is governed by the mode of fiber breakage and fiber slippage as determined by the yarn structure—fiber distribution and migration—rather than predominantly by fiber breakage compared with strength.