Fine-tuning heat resistance and impact toughness of natural rubber-toughened PLA at Various degrees of PLA/PDLA stereocomplexation

Abstract

This study represents a new investigation into the influence of stereocomplex crystal content within the blend system of natural rubber (NR) and polylactic acid (PLA), aiming to concomitantly enhance both the impact strength and thermal properties of PLA. The NR content was fixed at 15 wt%, while the amount of stereocomplex crystals was increased by adjusting the PLA:PDLA ratio from 100:0 to 50:50 corresponding to the PDLA content ranging from 0 – 42.5 wt%. Regarding the effect of NR alone, the incorporation of well-dispersed NR into PLA resulted in a significant improvement in the impact strength with a slight increase in heat resistance of PLA as NR acted not only as a toughening agent but also as a mild nucleating agent for PLA. The addition of PDLA, especially at higher contents, provided higher % crystallinity and crystallization rate of stereocomplex crystals, consequently enhancing the heat resistance of the blends. At the optimal PDLA content of 30 wt%, the molded specimens could successfully withstand a temperature of 100 °C throughout the 24-hour test with a 3-fold higher impact strength than that of neat PLA.