To address the increasing demand for high-quality stretch denim, new yarn designs are being developed to enhance the elasticity of the fabrics, mechanical strength and overall comfort. This research examines how the yarn structure and core components affect the mechanical, physical and dimensional characteristics of the yarn and the fabric made from it.
Fourteen types of yarns were made in rigid, core-spun, dual core-spun and Siro dual core-spun combinations by using cotton, elastane (EL), PBT (polybutylene terephthalate) and T400®. These yarns were subsequently used to produce fabric samples under controlled conditions to evaluate their performance at the fabric stage. One-way MANOVA was used to assess differences among yarn types.
The yarn strength varied between 10.75 and 16.89 cN/tex and yarn elongation varied between 6.07 and 9.93%. The Siro dual core yarn with PBT and EL (Y13) achieved the best YQI (11.90) and the highest extensibility (9.93%), illustrating the advantage of Siro structure in terms of yarn quality and extensibility. But, yarn strength did not have a direct correlation with fabric tensile strength. While yarn strength for Y5 was the lowest (10.75 cN/tex), the highest tensile strength for the fabric was measured in the weft direction (67.1 kgf), suggesting that fabric performance is also influenced by yarn elongation, interaction between yarns, integration of core into the yarns and load redistribution within the structure of the fabric. Fabric weft tensile strength ranged from 43.8 to 67.1 kgf, while weft tearing strength ranged from 5069 to 5787 gf. The highest fabric elasticity obtained was for Y7 (53.2%), while the highest stiffness was obtained for Y5 (1.79 kg). The results show that the performance of hybrid yarns is dependent not only on core composition, but also on the technique of incorporating the core components into them.
The cumulative findings of this study are that the structural engineering of yarn, especially that of dual core-spun and Siro dual core-spun yarns, can significantly improve the yarn uniformity, elongation and performance of the overall fabrics to be used in high-end denim and stretch fabrics.
