Phase behavior of polyethylene/ethylene vinyl acetate blends: Studies on miscibility window, composition dependency of interfacial interactions, and enhanced toughness

Abstract

Liquid–liquid phase separation of polyethylene/ethylene vinyl acetate copolymer binary blends was investigated employing rheometry, mechanical experiments, optical, and electron microscopy as well as thermal analysis. The observed phase diagram has shown that the studied polyethylene/ethylene vinyl acetate blends possess upper critical solution temperature behavior, i.e. phase separation of two components occurs in the molten state before polyethylene crystallization begins. Moreover, the interfacial interaction of phases was found to be dependent on the blend composition, and it varies considerably by the occurrence of phase inversion. In the solid state, however, the miscibility of phases is controlled by the melt temperature and cooling rate of final process. In addition, it was confirmed that imposing restrictions on phase separation leads to a noticeable improvement in the toughness of blends.