Study on the double cold crystallization peaks of poly(ethylene terephthalate) (PET): 2. Samples isothermally crystallized at high temperature

Abstract

The exothermic peak during the heating scan of differential scanning calorimeter (DSC) analysis is called the cold crystallization peak, originating from the crystallization of the amorphous regions. In this work, we further use the cold crystallization peak in DSC scans as a probe to study the structure in the amorphous regions of poly(ethylene terephthalate) (PET). For PET samples properly treated at high temperature near the melt temperature, double cold crystallization peaks also appear in DSC scanning. This fact may have a relation to the co-existence of two kinds of amorphous regions: interlamellar amorphous regions and complete amorphous regions between spherulites. The difference and changes in position, height and shape of peaks reflects the change in structure of amorphous regions under treatment conditions. The difference in cold crystallization behavior between samples treated at low temperature and at high temperature is also discussed.