Rheological and thermal behavior of PLA modified by chemical crosslinking in the presence of ethoxylated bisphenol A dimethacrylates

摘要

Crosslinking structures can be partly introduced into PLA by melt mixing in a twin screw extruder with dicumyl peroxide (DCP) and ethoxylated bisphenol A dimethacrylates (Bis-EMAs) as a crosslinking coagent. The study of DCP and Bis-EMA contents on the melt rheology, thermal properties, dynamic mechanical properties and morphology of the reactive extruded pellets is presented. The results show that PLA with a DCP content higher than 3 phr exhibits increases in both the melt modulus and complex viscosity as compared with PLA. The introduction of DCP into PLA improved the thermal stability of the PLA. PLAs with various Bis-EMA contents showed the optimum storage modulus and complex viscosity to occur at 5 phr Bis-EMAs. Moreover, the glass transition, cold crystallization and melting temperature of PLAs decreased with increasing Bis-EMA content. The crystallinity of the partly crosslinked PLAs was lower than that of PLA. Similar to the rheological results, the thermo-mechanical properties showed that the storage modulus and loss modulus of the partly crosslinked PLAs increased with increasing Bis-EMA contents up to 5 phr. In addition, these partly crosslinked PLAs showed rough surface or sea island-like structure. Copyright (c) 2016 John Wiley & Sons, Ltd.