The formation and disruption of reversible physical crosslinking structure of polyether-block-amide under high temperature

This study investigates the structural evolution under thermal treatment in an inert atmosphere of polyetherblock-amide (PEBA) based on PA1012 and PTMO. Thermal analysis, nuclear magnetic resonance (NMR), insitu small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD), rheology, and in situ infrared spectroscopy are employed to characterize the structure evolution, with a focus on both chemical and physical aspects. After the thermal treatment at 260 degrees C for 60 min in nitrogen atmosphere, the chemical analyses of the sample show minimal reactions at the repeating unit scale, with only slight post-condensation. The main finding in this work is the suppression of crystallization in polyamide hard segments. Other key physical performances like glass transition temperature (Tg) and Brill transition temperature (TB) are largely unaffected, with the TB only shifts from 64 degrees C to 61 degrees C detected by WAXD. The observed changes are attributed to the formation of a denser non-chemical-crosslinking network structure, which reduces crystallization temperatures. Rheological measurements indicate that this network is reversible and can be disrupted by shear. This research enhances understanding of PEBA's non-chemical-crosslinking network structure and its potential for controllable processing and functional design in high-performance materials.