Super-Tough Poly(lactic Acid)-Based Thermoplastic Vulcanizate Based on Selective Dispersion and In Situ Compatibilization of Commercial Reinforcing Fillers and Its Application in Three-Dimensional Printing

Abstract

Blending with elastomers is a commonly used method to improve the toughness of poly(lactic acid) (PLA). However, the poor compatibility between polar PLA and the nonpolar elastomer results in a limited improvement of the toughness. In this work, we report a simple but effective strategy to improve the compatibility between PLA and natural rubber (NR) and manufacture super-tough PLA-based thermoplastic vulcanizate (TPV). We choose the widely used reinforcing filler SiO2 nanoparticles as the compatibilizer, whose modification using 3-(trimethoxysilyl)propyl methacrylate (KH570) is synchronized with the dynamic vulcanization. Simultaneously, the modified SiO2 nanoparticles migrate from the NR phase to the PLA/NR interface due to the interfacial tension. The modified SiO2 nanoparticles located at the interface entangle with the NR chains on the one hand and graft with the PLA chain on the other hand, acting as a “bridge” to improve the interfacial compatibility of the two phases. While only adding a small amount of filler, 20 phr SiO2 nanoparticles in NR and 7 phr modifier in SiO2, the impact strength of the PLA/NR (80/20) TPV increases to 95.96 kJ/m2 (without fracture), which is 38-fold than pure PLA. Even in a low temperature of −30 °C, the impact strength is still 7.93 kJ/m2. Finally, the co-continuous structure and the excellent toughness with a small amount of toughener make the TPV have great potential for application in the 3D printing field (processing speed of 110 m/min, over 100 times bend after immersion in hot water).