12—A STUDY OF YARN TORQUE AND ITS DEPENDENCE ON THE DISTRIBUTION OF FIBRE TENSILE STRESS IN THE YARN PART II: EXPERIMENTAL

Abstract

Experimental measurements of yarn torque made on statically twisted continuous-filament and staple-fibre yarns are presented. The torque–twist and recovery characteristics of the yarns are interpreted in the light of the theoretical analyses derived in Part I of this series, and it is shown that the torque generated in continuous-filament yarns is in excellent agreement with that predicted for a yarn structure in which no fibre migration takes place. Staple-fibre yarns, on the contrary, have torsional properties that suggest that the fibres migrate freely until relatively high yarn-twist levels are reached, whereupon the lateral forces created in the yarn begin to impede migration and give rise to an increasing level of torque.