Mechanical properties, rheological behaviors, and phase morphologies of high-toughness PLA/PBAT blends by in-situ reactive compatibilization

Different ratios of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends were prepared by melt blending in the presence of a multifunctional epoxy oligomers as reactive compatibilizer. During reactive blending, the compatibilizer could react with PLA and PBAT chains to increase melt elasticity, viscosity, and compatibility, as indicated by rheological curve and Han plot analyses. Adding the compatibilizer improved the tensile and impact toughness for all ratios of PLA/PBAT blends. The elongation at break and the notched impact strength of the blend reached 579.9% and 29.6 kJ/m(2), respectively, which were 75.3 and 12.3 times that of neat PLA. The shear yield deformation of impact fractured surface and the fuzzy phase interface of cryo-fractured surface showed that the high toughness can be attributed to the reaction of the epoxy group of reactive compatibilizer with the terminal carboxyl and hydroxyl groups of PLA and PBAT to form a large number of branched copolymers. Thus, the improvement of the interfacial adhesion and compatibility of the two polymers induced that brittle-ductile transition occurred in the failure of the blend.