Preparation of High‐Performance <scp>PBS</scp> ‐ <scp>COOH</scp> / <scp>EVA</scp> Composite Foams via Carboxyl Grafting and Hydrogen Bonding Interfacial Modification

ABSTRACT Ethylene‐vinyl acetate copolymer (EVA) foam is widely used but is non‐biodegradable, raising environmental concerns. Existing green modification methods suffer from poor interfacial compatibility, low melt strength, cell collapse, and degraded mechanical properties, making it difficult to balance degradability and high performance. Herein, this study investigates the effect of Poly(butylene succinate) (PBS) with different molecular weight distributions on PBS/EVA blends and foams. Then, carboxyl groups are grafted onto PBS chains (PBS‐COOH), and the resulting hydrogen bonding between carboxyl groups and ester groups of EVA improves interfacial compatibility. The contact angle measurement results confirm the positive effect of hydrogen bonding. Specifically, while the theoretical interfacial tension of PBS‐COOH/EVA increased by 31.7% compared to that of PBS/EVA, its actual foaming compatibility improved significantly (maximum PBS‐COOH loading: 40 phr, compared to 30 phr for unmodified PBS). As a result, the PBS‐COOH/EVA (3/7) composite foam exhibits a reduced average cell size (from 80 μm in pure EVA foam to 39 μm) and a cell density of 14.2 × 10 9 cells/cm 3 . Its compressive strength at 70% strain is 7.5 times that of pure EVA, and over 90% of the strength is retained after 400 cycles, demonstrating excellent mechanical properties and fatigue resistance.