Hydrolytic degradation and lifetime prediction of poly(lactic acid) modified with a multifunctional epoxy-based chain extender

Abstract

The effect of adding chain extender (Cex) during the production of poly (lactic acid) (PLA) films on the hydrolytic degradation of the films was evaluated at temperatures from 40 to 95 °C. The hydrolytic degradation of PLA–Cex film estimated using the Pan model was significantly lower than that of neat PLA film (PLA–Con) at all temperature conditions. The Vogel-Tammann-Fulcher and Williams-Landel-Ferry models were used to study the hydrolytic degradation of the PLA films over a broad range of temperature crossing Tg. A master curve technique was constructed using the time-temperature superposition principle to predict the lifetime of PLA films at any temperature in the tested range. Specifically, accelerated degradation testing at 85 °C was used to predict the degradation behavior at 40 °C. Findings indicate that PLA–Cex would take approximately 130% more time than PLA–Con to degrade to the critical molecular weight for chain entanglement of PLA.