Relationship between Sequence Distribution and Thermal Properties of the Transesterification Product between Poly(ethylene terephthalate) and Poly(butylene terephthalate)

Abstract

The relationship between the number-average sequence length and the melting temperature of the block copolyesters prepared by quench after the transesterification reaction between poly(ethylene terephthalate) and poly(butylene terephthalate) was reported. The number-average sequence length was determined by the triad sequence analysis in a solvent system of o-chlorophenol/deuterated chloroform mixture (75/25 v/v) at 80 °C using 600 MHz 1H NMR. The melting temperature was observed using a differential scanning calorimeter. The linear correlation between the melting temperature and the inverse of the number-average sequence length was observed for the transesterification products with composition of PET/PBT from 20/80 to 80/20 mol %. This correlation was confirmed by the measurement of the long period using small-angle X-ray scattering. For the transesterification products obtained under definite conditions such as the quench after the transesterification reaction, it was confirmed that the number-average s...