Super toughed poly (lactic acid)/poly (ethylene vinyl acetate) blends compatibilized by ethylene-methyl acrylate-glycidyl methacrylate copolymer

Abstract

Poly (lactic acid) (PLA), as a biodegradable and biocompatible polymer, has attracted extensive attention and investigation in recent years. However, the inherent brittleness of PLA greatly limits its application. In this work, super toughed PLA-based blends were prepared by facile melt blending of PLA with poly (ethylene vinyl acetate) (EVA) and compatibilized by ethylene-methyl acylate-glycidyl methacrylate (E-MA-GMA), owing to the partial miscibility with EVA domains and the chemical reactions with PLA matrix of E-MA-GMA. Micromorphology reveals that E-MA-GMA effectively tunes the interface interactions and phase morphology of the incompatible PLA and EVA. Increasing the E-MA-GMA content promotes the phase adhesion and increases the interface thickness, thus producing a super-toughened blend behaving an incomplete fracture during impact tests. The maximum impact strength (about 77.6 kJ/m2) was obtained for the ternary blend with 12 wt% E-MA-GMA, which is 27.7 times higher than that of neat PLA. Rheological studies showed that the viscosity was enhanced for the ternary blends with large amounts of E-MA-GMA at low frequency. The PLA crystallinity was suppressed and the thermal stability was improved in the ternary blends. Micromechanical deformations and toughening mechanisms were studied, indicating that the matrix shear yielding, induced by the improved interface adhesion and the formed semi-continuous microstructure, was the main source for impact energy dissipation.