Largely toughened poly(lactic acid) fabricated by melt blending with thermoplastic polyurethane through interfacial compatibilization induced by simultaneous addition of hydrophobic silica nanoparticles and in situ cross‐linking reaction

Abstract

Polylactic acid (PLA) has gained significant attention as a commercially available biodegradable and biocompatible polymer. However, the brittleness of PLA greatly limits its application. Blending PLA with another rubbery polymer such as thermoplastic polyurethane (TPU) is a simple strategy to toughen PLA. In this study, a largely toughened PLA has been successfully prepared by melt blending with TPU through interfacial compatibilization induced by the simultaneous addition of hydrophobic silica nanoparticles (NPs) and in situ cross‐linking reaction. The torque evolution during melt mixing and rheological analysis confirm a successful dynamic vulcanization process. Scanning electron microscopy images indicate that, dynamic vulcanization and adding NPs synergistically compatibilize the TPU and PLA phases leading to a considerable interfacial adhesion between the phases. Simultaneous addition of NPs at an optimum amount of 5 wt% and in situ cross‐linking reaction significantly improve the elongation at break, and tensile toughness of the PLA/TPU blend as they are achieved 311%, and 91 MJ/m3, respectively. Both dynamic vulcanization and NPs play their role independently in the compatibilization of PLA and TPU phases inducing substantial shear yielding of the matrix phase under stress resulting in a highly toughened blend. The microstructural properties of the blends are studied by rheological analysis.