MISCIBILITY OF CAPROLACTONE ETHYLENE TEREPHTHALATE COPOLYMERS WITH CHLORINATED POLYMERS - A DIFFERENTIAL SCANNING CALORIMETRY AND FOURIER-TRANSFORM INFRARED STUDY

Differential scanning calorimetry was used to determine the miscibility and phase behaviour of poly(ethylene terephthalate-co-caprolactone)/chlorinated polymer blends. Five copolymers differing in poly(ethylene terephthalate) (PET) content were blended with poly(vinyl chloride) (PVC), a chlorinated PVC (CPVC) with a chlorine content of 67.2% and a chlorinated polyethylene (PECL) with a chlorine content of 48%. The results show that CPVC is miscible with each of the copolymers investigated, provided that the blends are annealed between Tg and their lower critical solution temperature (LCST). However, PVC is only miscible with copolymers containing 33 and 44% PET, whereas PECL is miscible only with the copolymer containing 33% PET. Miscibility is more easily achieved with chlorinated polymers of a high chlorine concentration. A LCST was observed with blends of CPVC with copolymers containing 64 and 89% PET. Furthermore the LCST of the former blend occurs at a higher temperature than that of the latter. This difference is caused by a decrease of intermolecular interactions and/or intramolecular repulsions, which coexist in these mixtures. A LCST was also observed in blends of PECL with the copolymer containing 33% PET. Some measurements were made with PET/poly(caprolactone) blends, which were found to be immiscible, and the importance of specific interactions (attractive and repulsive) are discussed. © 1990.