Fabrication of Ultralight and Highly Elastic <scp>PEBA</scp> / <scp>TPAE6</scp> Foams With Tunable Structures and Enhanced Foamability via Supercritical <scp> CO ₂ </scp> Foaming

ABSTRACT Thermoplastic polyamide 12 elastomer (TPAE12) offers excellent thermal stability, mechanical tunability, and chemical resistance, making it promising for elastic foams. However, its low melt strength often leads to pore collapse and poor elasticity. Here, TPAE12 (PEBA) was blended with cost‐effective TPAE6 and foamed using supercritical CO 2 to produce lightweight composite foams. Adding just 10 wt% TPAE6 enhanced melt strength, inhibited pore coalescence, and promoted homogeneous nucleation by creating zigzag gas diffusion paths through microphase separation. Therefore, the expansion coefficient of the composite foam increased by 31% compared to pure PEBA, with a density as low as 0.071 g/cm 3 , which is comparable to the density level of commercial PEBA bead foams. Notably, this ultra‐low density was achieved by adding only 10 wt% of TPAE6, significantly reducing the raw material cost of the foam system. The study also found that smaller bubble sizes correspond to higher compression stability and resilience, whereas larger bubbles weaken these performance metrics. Compared with pure PEBA foam, this composite foam presented a uniform closed‐cell structure without cell fusion/collapse. Therefore, these findings demonstrate that super‐elastic PEBA/TPAE6 composite foams—with their lightweight, highly elastic, and structurally tunable character—hold strong promise for advanced footwear material applications.