Mechanical and rheological properties of poly(lactic acid) toughened by bio‐based thermoplastic polyamide elastomer

Abstract Polylactic acid (PLA)/thermoplastic polyamide elastomer (TPAE) blends were prepared by melt‐compounding on a two‐roll mill. The effects of the TPAE content on the mechanical properties, thermal stability, and rheological behaviors of the blends were fully investigated. With the incorporation of 30 wt% TPAE, the elongation at break and impact strength of the PLA/TPAE blend were increased by 34 times and 3.5 times as compared with the neat PLA, respectively. The improved toughness and tensile ductility were contributed to by the stress whitening and shear plastic deformation, which can absorb energy when subjected to external work. The thermal stability of the PLA/TPAE blends was slightly decreased with the incorporation of the TPA. The dynamic mechanical analysis showed that the blends possessed better elasticity and toughness at low temperatures, and the presence of the TPAE promoted the cold crystallization of the PLA. The rheological behaviors demonstrated that TPAE was compatible with PLA, and obvious chain entanglement occurred between them, resulting in a heterogeneous structure with fine phase separation. Highlights TPAE ensured the overall biodegradability of the toughened PLA. TPAE enhanced the elongation at break and impact strength of the PLA blend. The toughening mechanism and rheological properties were investigated.