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 (T-c) from 130 to 170 degrees C. The melting behavior after isothermal crystallization was studied using DSC and temperature-modulated DSC by varying the T-c, 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 T-c increases, the contribution of recrystallization gradually falls and finally disappears. A Hoffman-Weeks linear plot yields an equilibrium melting temperature of 198.7 degrees 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 degrees C. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2305-2314, 2009