Enhancing Impact Toughness of Renewable Poly(lactic acid)/Thermoplastic Polyurethane Blends via Constructing Cocontinuous-like Phase Morphology Assisted by Ethylene–Methyl Acrylate–Glycidyl Methacrylate Copolymer

Poly­(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends and their ternary blends with the incorporation of ethylene–methyl acrylate–glycidyl methacrylate copolymer (E–MA–GMA) were prepared by melt blending. The PLA/TPU (70/30) blend exhibited optimum elongation at break of 615% and impact strength of 53.6 kJ/m2. Compared with PLA/TPU (90/10) blend, the impact strength of PLA/TPU/E–MA–GMA (80/10/10) blend increased by more than 15 times; meanwhile, the elongation at break did not suffer apparent reduction. Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) revealed the reaction and miscibility between components. Morphological observation by scanning electron microscopy (SEM) confirmed the transition from typical sea–island to cocontinuous-like structure due to the addition of E–MA–GMA. The toughening mechanism behind the supertoughened PLA ternary blends was established. The cocontinuous-like structure followed by massive plastic deformation of PLA matrix was believed to be responsible for the enormous toughening effect.