Investigation of Reactive Compatibilization on Degradable Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends with Lysine Diisocyanate

Biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends have poor compatibility, and reactive compatibilization is the most effective approach to improve their compatibility. In this study, lysine diisocyanate (LDI) is employed as a reactive compatibilizer to improve the interfacial interactions within PLA/PBAT blends at various ratios (30/70, 50/50, and 70/30). The effects of LDI on the reactive mechanism, thermodynamic behavior, mechanical properties, and phase morphology of the blends are thoroughly investigated. Fourier Transform Infrared Spectroscopy (FTIR) analysis shows that LDI react with the carboxyl terminal group of the PLA and PBAT to form copolymers, which serve as a chemical bridge between the two phases. Thermodynamics behaviors show that LDI reduces the crystallization rate and crystallinity of the blends. Mechanical property studies prove that LDI significantly improves the comprehensive properties of the blends, and the elongation at break, elastic modulus, and tensile strength are optimal for LDI at 2 wt.%. Impact strength even exceeds 90kJ m⁻² for PLA/PBAT (50/50) blends at above 2 wt.% LDI. The morphology studied by Scanning Electron Microscopy (SEM) shows that the addition of LDI can emulsify the two-phase interface, change the sea-island structure into a co-continuous one, and improve the affinity between the two components.