Polylactic Acid Based Blends and Biocomposites with Improved Performance

Abstract

In an effort to improve the toughness of PLA, multiphase blends of PLA, ethylene-methyl acrylate-glycidyl methacrylate (EMAGMA) terpolymer and a partially biobased thermoplastic copolyester elastomer, Hytrel (HYT) were fabricated through reactive melt blending. High impact strength with non break behavior was achieved at an optimized blending ratio of 70 wt% PLA, 20 wt% EMAGMA and 10 wt% HYT. A unique morphological structure with partial encapsulation of GMA and HYT minor phases was observed for the PLA/GMA/HYT (70/20/10) blend revealing the importance of particular blend morphology and composition in enhancing the toughness. In order to achieve concurrent improvements in impact strength and heat deflection temperature (HDT) of PLA, the super-toughened blend was combined with natural fibers and nucleating agents to fabricate PLA biocomposites. Mechanical and thermal properties assessment revealed a 4 fold increase in impact strength compared to neat PLA and the HDT of PLA biocomposites increased to 88°C from 55°C noted for neat PLA and PLA blends. With the addition of 1 wt% Lak-301 as nucleating agent at mold temperature of 110°C PLA biocomposites exhibited dramatic reduction in crystallization half time to 1.3 min with crystallinity content of 42%.