Mechanical Enhancement, Biodegradation, and Phytotoxicity Assessment of Poly(Dicyclopentadiene-co-Maleic Anhydride) Compatibilizer on PBAT–PLA Blends

Blends of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) attract intensive interest as biodegradable alternatives to conventional plastics. However, the intrinsic incompatibility between PBAT and PLA limits their practical applications. To address this limitation, poly(dicyclopentadiene-co-maleic anhydride) (PDM) was synthesized via self-stabilized precipitation polymerization and used as a compatibilizer. The effects of PDM on the mechanical properties, biodegradation behavior, and phytotoxicity of the PBAT–PLA blends were systematically investigated. The results demonstrated that PDM chemically interacted with both PBAT and PLA, enhancing the interfacial compatibility and mechanical performance. At 2.5 phr of PDM, the blend with optimal mechanical properties was achieved with tensile strength increasing from 23.0 to 31.2 MPa. Biodegradation experiments revealed that PDM improved structural stability and slowed degradation, and the cumulative CO2 release for PBAT–PDM-PLA was 11.02% lower than pristine PBAT–PLA. Furthermore, PDM exerted negligible effects on soybean seedling growth within the experimental period.