Optimizing core yarn twist levels for enhanced mechanical properties of aramid-wrapped yarns and fabrics

This study addresses the issue of low surface energy of aramid fibers and their fabrics and aims to enhance their mechanical properties including tensile strength and impact resistance. Using the hollow spindle spinning method, aramid fiber bundles are employed as the core yarns with varying twist levels and nylon fibers are used as the wrapping yarns to create the nylon/aramid-wrapped yarns, which are then woven into the nylon/aramid fabrics. The investigation focuses on the effect of core yarn twist levels on the mechanical properties of the yarns and fabrics. Experimental results reveal that applying an appropriate core yarn twist can significantly improve the mechanical properties of the yarns and fabrics. Specifically, with the optimized the core yarn twist of 80 turns per meter (tpm) the tensile and hook strengths of the wrapped yarns reach 3.3 GPa and 1.2 N/Tex, respectively which are about 20.6% and 21.7% increase as compared to the untwisted yarns. Similarly, the plain-woven fabric consisting of the 80 tpm yarns achieves a tensile strength of 2577.9 N/cm, a pull-out force of 160.2 N, and an absorbed energy per unit volume of 436.5 KJ/m 3 which are about 20.0%, 31.4% and 30.1% improvement, respectively as compared to the fabrics with the untwisted yarns. Additionally, the optimized fabric presents a 28.4% increase in the energy absorption efficiency and significant enhancement in abrasion resistance. These findings offer valuable insights for the potential applications of the nylon/aramid-wrapped yarns for developing personal protective fabrics and products.