Poly(lactic acid)/biobased polyurethane blends with balanced mechanical strength and toughness

The mechanical strength and modulus of poly(lactic acid) (PLA) are usually reduced significantly during toughening modification. Herein, we report a PLA blend with balanced strength and toughness via incorporation of a biobased polyurethane (COIPU) consisting of castor oil (CO) and isosorbide (IS) through dynamic vulcanization. The composition of COIPU played an important role in the morphology and the final mechanical properties of the PLA/COIPU blends. The compatibility between PLA and COIPU increased with increasing IS content, as shown by the gradually reduced particle size of the dispersed COIPU phase. The tensile strength and Young's modulus increased gradually while the elongation at break and notched Izod impact strength first increased and then decreased with increasing IS content. The blend with balanced mechanical strength and toughness may find extensive application where both toughness and high strength are required.