Modification on crystallization behavior and mechanical properties of polylactide by the addition of polyamide elastomer

The phase morphology, crystallization behavior, and mechanical properties of polylactide (PLA) modified by polyamide elastomer (PAE) have been systematically investigated. SEM images showed that PAE was homogeneously dispersed in the PLA matrix forming a sea-island morphology. The dimension of PAE domains increased slightly with its content and still remained smaller than 3 mu m even at 40 wt% due to the partial compatibility of PLA and PAE. PAE had some nucleation effect on PLA and promoted the crystallization of PLA to a certain extent. The crystallization kinetics and crystalline morphology, especially the nucleation and growth of PLA crystals, were compared in detail between pure PLA and PLA/PAE blends. The elongation at break and impact strength of PLA were considerably improved by PAE. The sample PAE20 exhibited the best rigidity-toughness balance showing ductile failure. The toughening mechanism was proposed based on the deformation of the impact fracture surfaces.