Comparisons of Core—Sheath Structuring Effects on the Tensile Properties of High-Tenacity Ring Core-Spun Yarns

Abstract

The structuring effects of the core and sheath on the tensile properties of core-spun yarns need to be systemized in order to meet potential application requirements. In this study, the core— sheath structuring effect was modeled theoretically, using a spring and damper as mechanical elements. Core-spun yarns with high tenacity filaments as the core and cotton staples as the sheath were prepared and tested to determine their tensile properties. Results demonstrated that the tensile system of the ring core-spun yarn could be described with four mechanical elements, two elements for the core-sheath geometry and two elements for the structuring effect. The core-spun yarns had a lower elastic modulus than the core filaments, and an easy viscous deformation of the core-spun yarn occurred with core spinning. Increasing the number of twists led to a consistent decrease in the strength of aramid core-spun yarn, while the high tenacity PET core-spun yarn had almost unaffected tenacity for various twist levels. The basalt core-spun yarn, however, demonstrated a twist factor level that indicated a potential maximum yarn tenacity. The breaking elongation of the aramid core-spun yarn had an increasing tendency with the number of twists. The high tenacity PET core-spun yarn remained in a limited range of elongation with twists. The basalt core-spun yarn had noticeably greater elongation as the number of twists increased.