Supercritical CO 2 Foaming of PBAT / TPEE Blends With Chain Extension: Toward Low‐Shrinkage, High‐Resilience and Thermal‐Insulating Biodegradable Foams

ABSTRACT As a representative biodegradable copolymer with both aliphatic and aromatic segments, poly (butylene adipate‐co‐terephthalate) (PBAT) has attracted tremendous interest for fabricating green porous materials owing to its excellent toughness and processability. However, unmodified PBAT suffers from insufficient melt strength and poor foam stability, which severely restrict its real‐world applications. In this work, we developed a combined strategy of chain extension and elastomer blending to address these issues, and successfully prepared high‐performance PBAT composite foams via supercritical CO 2 (scCO 2 ) solid‐state foaming. PBAT was first modified with an epoxy chain extender (CE) and thermoplastic polyester elastomer (TPEE) through melt blending, which effectively regulated the rheological behavior and crystallization behavior of the matrix. The introduction of CE built a stable cross‐linked network, while TPEE served as a reinforcing phase and a heterogeneous nucleation agent to refine cell morphology. Benefiting from the combined effect, the optimized PBAT/CE/TPEE foam achieved a uniform cellular morphology with a mean pore size of 80 μm and the cell density up to 4.89 × 10 6 cell/cm 3 . In parallel, the PBAT/CE/TPEE foam showed a negligible volume shrinkage of 3.4%, a high ball rebound resilience of 49%, and a thermal conductivity as low as 50.18 mW/(m·K), together with remarkable cyclic compression stability. This study proposes a straightforward and efficient method to prepare low‐shrinkage, high‐resilience, and thermal‐insulating biodegradable polymer foams, which shows great potential in green cushioning and thermal insulation fields.