The Effect of Different Acrylic-Based Rubbers on the Crystallization Behavior of PLA/PDLA Stereocomplex

Abstract

This study investigated the performance of two acrylic rubbers on the improvement of mechanical and thermal properties of polylactic acid (PLA)/ poly(D-lactide) (PDLA) stereocomplex. The selected acrylic-based rubbers consisted of a commercial acrylic rubber (ACM) and acrylic core–shell rubber (CSR). In this work, 5 wt% PDLA was melt-blended with PLA to form PLA/PDLA stereocomplex (ST) in the presence of a 15 wt% acrylic-based rubber in an internal mixer at 180 °C and 50 rpm. It was found that the small amount of PDLA could successfully form stereocomplex crystals with PLA during melt mixing. The addition of acrylic-based rubbers not only increased the impact strength of the blends but also assisted PLA in forming more perfect crystals. This is because the rubbers could act as nucleation sites for PLA crystallization leading to smaller spherulite size than that of neat unmodified PLA. Comparatively, CSR could provide much higher %crystallinity with quicker nucleation onset than ACM in both PLA and ST systems, even though the crystallization rate was lower. In terms of mechanical properties, CSR also contributed to the highest impact strength due to the smaller size of CSR than ACM in both PLA and ST systems.