Super‐Toughened Heat‐Resistant Poly(lactic acid) Alloys By Tailoring the Phase Morphology and the Crystallization Behaviors

ABSTRACT The interfacial grafting copolymerization and the compatibility between poly(lactic acid) (PLA) and ethylene‐vinyl acetate‐glycidyl methacrylate elastomer (EVM‐GMA) are adjusted by varying the blending temperatures. High temperature is favored to the grafting reaction between epoxy groups of the EVM‐GMA and terminal groups of the PLA, resulting in better compatibility between the two components. Taking PLA/EVM‐GMA (80/20) blend as an example, an increase in blending temperature from 175 to 230 °C led to a 42.8% reduction in EVM‐GMA particle size, and consequently 137.8% and 52.6% increases in elongation at break (Eb) and notched impact strength (NIS), respectively. In comparison, the Eb and NIS of PLA/EVM blends without any interfacial reaction deteriorated dramatically due to thermal degradation of the PLA at high(er) temperatures. Furthermore, the PLA/EVM‐GMA blend prepared at 230 °C possesses both excellent toughness (Eb > 60%, NIS > 60 kJ m−2) and high heat deflection temperature (>90 °C) after annealing at 100 °C. This work provides a new approach in designing high‐performance biobased materials which may broaden the application range of PLA in engineering areas. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 500–509 Reactive blending with ethylene‐vinyl acetate‐glycidyl methacrylate elastomer (EVM‐GMA) is an effective approach to enhance the toughness of poly(lactic acid) (PLA). The interfacial grafting copolymerization and the compatibility between PLA and EVM‐GMA are adjusted by varying the blending temperatures. High temperature is favored for the grafting reaction between epoxy groups of EVM‐GMA and terminal groups of PLA, resulting in better compatibility of the two components and consequently higher toughness of the blends.