Crystallization kinetics and melting behavior of poly[(trimethylene terephthalate)-co-(29 mol % ethylene terephthalate)] copolyester



The copolyester was characterized as having 71 mol % trimethylene terephthalate units and 29 mol % ethylene terephthalate units in a random sequence according to the NMR spectra. Differential scanning calorimeter (DSC) was used to investigate the isothermal crystallization kinetics in the temperature range (Tc) from 130 to 170°C. The melting behavior after isothermal crystallization was studied using DSC and temperature-modulated DSC by varying the Tc, the crystallization time, and the heating rate. The DSC thermograms and wide-angle X-ray diffraction patterns reveal that the complex melting behavior involves melting-recrystallization-remelting and different lamellar crystals. As the Tc increases, the contribution of recrystallization gradually falls and finally disappears. A Hoffman-Weeks linear plot yields an equilibrium melting temperature of 198.7°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 148°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009