Toughening Poly(Lactic Acid) By Melt Blending With Poly(Ether-Block-Amide) Copolymer

Melt blending with poly(ether-b-amide) copolymer (PEBA) was found to significantly enhance the toughness of poly(lactic acid) (PLA). The miscibility, morphology, thermal behavior, mechanical properties and rheological behavior of the blends were investigated. DMA and DSC analysis revealed that the PLA/PEBA blends were immiscible. A clear, phase-separated morphology was observed from SEM results. The addition of PEBA enhanced the cold crystallization of the PLA in the blends and accelerated the crystallization rate due to the interfacial function between PLA and PEBA phases, Significant enhancement of the toughness of PLA was achieved by the incorporation of PEBA copolymer. The optimum impact modification of the PLA was obtained by blending with 20 wt% PEBA, with an elongation at break of 300% as compared to 5% for pure PLA. The impact strength was ten times higher than that of the pure PLA. SEM results showed that the interfacial cavitation followed by a massive shear yielding of the matrix contributed to the increased toughening effect in the blends. The rheological measurement revealed an interaction between PLA and PEBA in the melt state.