Polyamide-6-Based Thermoplastic Elastomers and Their Filaments with Improved Thermomechanical Performance Enabled by Enhanced Hydrogen Bonding Interactions

Enhancing the glass transition temperature of the hard phase (Tg-HS) and the tensile strength of PA6-based thermoplastic elastomers (TPAEs) has been a long-standing challenge, significantly restricting their application in textiles. In this study, this issue was effectively addressed by incorporating p-phenylenediamine (PPD) into the molecular chains, which induces enhanced hydrogen bonding interactions in TPAEs. Consequently, the prepared PPD-modified TPAEs (PPD-TPAEs) demonstrated a well-defined nanophase-separated morphology and a Tg-HS of 48.2 °C, which is more than 5 °C higher than that of TPAEs with the same soft segment weight concentrations (CSS). Additionally, the Tg-HS increased with higher CSS values due to the augmented hydrogen bonding interactions in PPD-TPAEs. The tensile strength and elongation at break of PPD-TPAEs were over 1.9 and 2.6 times greater, respectively, than those of TPAEs with the same CSS value. Notably, filaments produced from molten PPD-TPAEs with 44% soft segments (PPD-TPAE-40) exhibited thermomechanical performance comparable to Spandex, underscoring their potential application in the textile industry.