Properties of wool/PET composite yarns

This paper reports an investigation of the differences in structures and mechanical properties of two kinds of composite yams and of conventional two-ply staple yarns. The cross section of one composite yams (Sirofil) shows a circular shape, which is similar to the structure of single spun yams and to the helical geometry line of two-ply yarns. The other composite yam structure (twisted ring spun singles yarns with filaments) is similar to that of two-ply yams. The tensile properties of composite yarns mainly depend on the tensile properties of the filaments, and their tenacity is higher than that of two-ply wool/PET staple fiber yarns. The bending rigidity of these two kinds of composite yams is lower than that of two-ply staple fiber yams. Wool/PET composite yams show higher residual torque than conventional two-ply staple yarns, and the reason is their structure and lower torque-relaxation.