Super-elastic and structure-tunable poly(ether-block-amide) foams achieved by microcellular foaming

Poly(ether-block-amide) (PEBA) is an advanced thermoplastic elastomer that has very low material density and excellent resilience over a wide temperature range. High-performance PEBA foams enabled by microcellular foaming show great prospects in sports, safety protection, and medical rehabilitation, yet their preparation is still greatly limited by the unclear processing-structure-property relationships. Herein, microcellular foaming with CO2 as the blowing agent was developed to fabricate high-performance PEBA foams. Foaming temperatures and CO2 pressures were varied to investigate their effects on foam structure, and hence PEBA foams with a tailored cellular structure were achieved. With the structure-tunable PEBA foams, the processing-structure-performance relationships were clarified. It was demonstrated that a higher expansion ratio and larger cell size lead to significantly enhanced resilience and reduced energy loss coefficient. In particular, PEBA foams with an expansion ratio of up to 24.5-fold were prepared, which possess a drop-ball resilience of up to 80 %, obviously superior to current foams. Moreover, the PEBA foams with larger cells exhibit significantly improved cyclic compression stability, and the minimum energy loss coefficient is lower than 15 %. The super-elastic PEBA foams with tailored structure exhibit promising prospects in advanced resilience applications.