Phase Structure Analysis and Composition Optimization of Poly(Lactic Acid)/Poly(Butylene Adipate-co-terephthalate) Blends

Poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends with different mass ratios of PLA and PBAT (PLA/PBAT: 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100) were prepared by a monomer melt blending method. The processability, mechanical properties, microstructure, thermal properties of the PLA/PBAT blends were tested. The change of phase structure of the PLA/PBAT blends with different proportions of its components was characterized and the relationship between phase structure and mechanical properties was determined. The results showed that the PLA/PBAT (80/20) blend had the best comprehensive performance of the blends with different properties; the torque test results showed that the maximum torque and balance torque of the PLA/PBAT (80/20) blend were 5.67% and 38.67% lower than those of PLA, respectively, while the mechanical properties tests showed that the impact strength of PLA/PBAT (80/20) blend was 4.27 times that of PLA. SEM test results showed that there were a large number of PBAT doming uniformly dispersed in the PLA matrix in the form of microbeads in the PLA/PBAT (80/20) blend while the results of the TGA tests showed that the Ts and T50% of the PLA/PBAT (80/20) blend increased by 3 °C and 6 °C compared to PLA, respectively, and the DSC tests results showed that the cold crystallization temperature of the PLA/PBAT (80/20) blend was 16 °C lower than that of PLA.