Study of non-isothermal crystallization kinetics and sequence distributionin poly(ethylene terephthalate-co-isophthalate)

The non-isothermal crystallization kinetics of poly(ethylene terephthalate- co-isophthalate) (PEI-T) with different isophthalate contents (4, 8 and 12% ) were studied by differential scanning calorimetry. Avrami exponent n was obtained. It was found that the n values of PEIT4 and PEIT8 are same as tha t of poly(ethylene terephthalate) (PET). The n value of PEITI12 is larger t han that of PET. PEIT crystallization mechanism appears different with vari ed isophthalate composition. The sequence distribution in macromolecular ch ain of PEIT was also investigated by H-1-NMR method. It revealed that PEIT4 and PEIT8 are block-copolymers with isophthalate sequence length > 5, and PEIT12 is a random copolymer in which most isophthalate sequence length is 2 or 1. The relationship between the crystallization mechanism and sequence distribution characteristic of PEIT has been discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.