Effect of Compatibilization of Thermoplastic Polyurethane with Poly(lactic acid) for the Preparation of Sustainable Blends

Poly(lactic acid) (PLA) is a prominent biopolymer highly recommended for resolving environmental concerns due to its biodegradability. To overcome its limitations of brittleness, blending with other polymers is common technique but results in phase separation. In this work, impact modification of poly(lactic acid) (PLA) has been carried out by melt blending with maleic anhydride grafted thermoplastic polyurethane (PLMTPU) and with acrylonitrile grafted thermoplastic polyurethane (PLATPU). The blends were prepared using twin screw extruder by melt mixing of PLA with grafted TPUs in ratios of 97.5/2.5, 95/5, 92.5/7.5, and 90/10 by weight percentage. The interfacial adhesion imparted through compatibilization shown pronounced improvement in the impact strength of PLATPU and PLMTPU by 88 and 28% respectively compared to the virgin PLA. Also, improvement in the elongation at break from 1.2% (PLA) to 4.4% (PLATPU) and 4.9% (PLMTPU) was observed. The mechanical studies were also compared with the theoretical models. Interestingly, incorporated flexibility to the PLA with ATPU and MTPU and the impeded effective stress transfer mechanism was evident on probing the morphology of the blends. The novel compatibilized blend of PLA with grafted TPU is potential candidate for packaging, biomedical applications and as a feed stock material in 3D printing technologies.