Reactive Compatibilization and Plasticization of Poly(Lactic Acid)/Poly(Butylene Succinate) Blends for Balancing Strength and Ductility

Abstract

Poly(lactic acid)/poly(butylene succinate) blends, which are composed of biodegradable aliphatic polyesters, are promising candidates for sustainable polymer applications. However, their poor interfacial compatibility limits the simultaneous improvement of strength and ductility. This study aimed to regulate the interfacial structure and mechanical response of 70PLA/30PBS blends through reactive compatibilization with a multifunctional epoxy chain extender and reactive plasticization with epoxidized soybean oil. The blends were prepared by reactive melt extrusion and characterized by mechanical testing, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results showed that 5 phr epoxy chain extender refined the dispersed phase and improved interfacial adhesion, giving a tensile strength of 76.89 MPa and an elongation at break of 261%. Further addition of 2 phr epoxidized soybean oil increased the elongation at break to 292% while maintaining a tensile strength of 65.06 MPa. The combined results suggest that the epoxy chain extender mainly provides reactive interfacial anchoring and structural support, whereas epoxidized soybean oil improves chain mobility and plastic energy dissipation. By distinguishing the effects of chain extender content, epoxidized soybean oil content, and premixing sequence within a fixed 70PLA/30PBS formulation platform, this work clarifies how reactive interfacial anchoring, reactive plasticization, and reaction‐distribution control jointly regulate crystallization behavior, interfacial morphology, and the strength–ductility balance of PLA/PBS blends.