Crystallization kinetics and melting behavior of poly[(trimethylene terephthalate)‐co‐(38 mol% ethylene terephthalate)] copolymer

Abstract

BACKGROUND: Modifications of semicrystalline polymers by copolymerization change both the crystallization kinetics and the morphology. Only a few studies concerning ethylene terephthalate (ET)/trimethylene terephthalate (TT) copolyesters have been published. This study extends the work on a series of random aromatic copolyesters. RESULTS: The copolyester was characterized as having 62 mol% TT units and 38 mol% ET units in a random sequence as revealed by NMR. Results of differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) show that the complex melting behavior involves melting-recrystallization-remelting and various lamellar crystals. As the isothermal crystallization temperature increases, the contribution of recrystallization slowly declines, and finally disappears. A Hoffman-Weeks linear plotgives an equilibrium melting temperature of 188.5 • C. The kinetic analysis of the growth rates of spherulites and the change in the morphology from regular to banded spherulites indicate that a regime II → III transition occurs at 135 • C. CONCLUSION: Results of DSC and WAXD demonstrate that this random copolyester is crystallizable. However, its crystallinity is only about 20%.

Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

“…In this kind of works, NMR has been invariably used in order to determine the comonomer composition and sequence distribution of the PTT copolyesters. One representative example is afforded by the study made on poly(ethylene‐ co ‐trimethylene terephthalate) (PE x T y T) copolyesters . In Figure , the 1 H NMR spectrum of the copolyester PE 70 T 30 T (abbreviated ET70 and made from a feed containing an EG/PDO ratio of 70/30) is compared to the spectra of the corresponding PET and PTT homopolyesters.…”

Crystallization behavior of poly(ethylene terephthalate)/pyrrolidinium ionic liquid

“…Effort on this subject includes copolymerization and reactive blending. Despite the capability for improving the properties, less attention has been paid to copolymerization due to the lengthy processes of designing and synthesis . As an alternative, polymer blending represents a simple and effective method for the development of new polymeric materials with improved properties.…”