Enhancing the Mechanical and Thermal Properties of Poly(L-lactide)/Poly(D-lactide) Stereocomplex with Polybutylene Adipate-co-Terephthalate: Innovative Biopolymer Solutions for a Sustainable Future

This study investigates the formation and reinforcement effects of stereocomplex polylactide (SC-PLA) when blended with poly butylene adipate-co-terephthalate (PBAT). SC-PLA was prepared by blending equimolar amounts of PLLA and PDLA, and then incorporated with PBAT at varying concentrations (10–30 wt%). The formation of stereocomplex crystals was confirmed by X-ray diffraction, which revealed characteristic diffraction peaks at 11.9°, 20.6°, and 23.9°, corresponding to the triclinic crystalline structure of SC-PLA. Differential scanning calorimetry (DSC) also confirmed the formation of SC crystallites, indicated by a distinct melting peak at ~ 224 °C, approximately 50 °C higher than that of homopolymeric PLA. SC-PLA enhanced tensile strength, modulus, and thermal stability, while PBAT improved ductility. Blends with 10–20 wt% PBAT demonstrated optimal mechanical performance, outperforming neat PLLA and PLLA/PBAT systems in both strength and elongation at break. Heat deflection temperature and thermal resistance analysis showed excellent dimensional stability at elevated temperatures, particularly in SC-PLA/PBAT systems. Scanning electron microscopy revealed improved phase morphology and reduced interfacial voids, suggesting physical compatibilization via SC crystallites. These results highlight the synergistic potential of SC-PLA and PBAT to create biodegradable materials with balanced strength, flexibility, and heat resistance for sustainable applications.