Abstract
In this study, 100% polyester and silk yarns and core-spun polyester silk yarns with two core/sheath ratios are produced. Fabrics are knitted from these yarns. Effect of core positioning on sheath coverage and core-sheath ratios and plying on various properties of yarns is analyzed. High level of unevenness is observed for core-spun yarns and plying improves many of the yarn characteristics. Z-twisted core-spun yarn produced with core filaments positioned left to the silk fibers during spinning has poor sheath coverage. Tenacity, elongation, and their CV are improved with increased percentage of core. It is observed that in a core-spun yarn sheath also contribute substantially to the yarn strength. The yarn to metal friction increases with increasing polyester content. Silk-rich core-spun yarn has less hairiness and better uniformity than the yarn with less silk content. Thermal comfort and wicking behavior of these fabrics are investigated in terms of fabric thickness, yarn structure, and fiber properties. The thermal conductivity of silk fabrics is the highest followed by silk rich and then polyester-rich fabrics. The thermal resistance of the fabrics is directly proportional to fabric thickness. The higher water vapor permeability, wicking, and transient heat flow observed for polyester and polyester rich fabrics indicate that they give an unpleasant cool effect to skin.