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 polyether-block-amide (PEBA) based on PA1012 and PTMO. Thermal analysis, nuclear magnetic resonance (NMR), in-situ 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°C for 60 minutes 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 (T_g) and Brill transition temperature (T_B) are largely unaffected, with the T_B only shifts from 64°C to 61°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.