CRYSTALLIZATION STUDIES OF BLENDS OF POLYETHYLENE TEREPHTHALATE AND POLYBUTYLENE TEREPHTHALATE.

Abstract

In the reported experiments, the compatibility of blends of polybutylene terephthalate and polyethylene terephthalate has been studied. A single glass transition for the blend is observed which varies with composition, suggesting that the components are compatible in the amorphous phase. Studies of the effects of time and temperature in the melt show that this is not a consequence of trans-esterification. X-ray, DSC, and IR studies demonstrate that crystallization results in separate crystals of the two components rather than cocrystallization. An IR technique, calibrated by density, was developed for measuring degrees of crystallinity of each component in the presence of the other. Crystallization rates are primarily affected by the degree of supercooling of each component in the blend and by the influence of blending on the glass-transition temperature.