Optimizing Thermo-mechanical and Shape-Memory Properties in Nanofibrous Yarns Through Twist Variation and Core–Shell Structure

This study aims to optimize the thermo-mechanical properties and shape-memory effect of twisted nanofibrous yarns featuring a core–shell structure for potential integration into thermo-responsive smart textiles via conventional processing methods, such as weaving and knitting. Twisted shape-memory polyurethane (SMPU) yarns were fabricated utilizing a double-nozzle electrospinning device, and the effects of twist amount and core–shell configuration on their structural, mechanical, and shape-memory properties were examined. Morphological analysis confirmed the production of uniform yarns with twist angles ranging from 7 to 21°, while differential scanning calorimetry (DSC) thermograms indicated a transition temperature of approximately 44 °C. Increased levels of twist resulted in a significant rise in maximum stress, approximately 36%, alongside an enhancement in Young’s modulus of about 30%, with elongation at break values within the range of 140% to 180%. The thermo-mechanical behavior was assessed at 50% and 100% strain over three cycles, demonstrating improved shape fixity and recovery with increased twist levels. Although exhibiting lower mechanical strength, core–shell yarns displayed comparable shape-memory performance to their single counterparts. These findings contribute valuable insights into the optimization of electrospun yarn structures for enhanced shape-memory functionality in the context of smart textiles.