Characterization, crystallization kinetics and melting behavior of poly(ethylene succinate) copolyester containing 5 mol% trimethylene succinate

Copolyester was synthesized and characterized as having 94.4 mol% ethylene succinate units and 5.6 mol% trimethylene succinate units in a random sequence as revealed by NMR. Differential scanning calorimeter (DSC) was used to investigate the isothermal crystallization kinetics of this copolyester in the temperature range (T-c) from 30 to 80 degrees C. The melting behavior after isothermal crystallization was studied by using DSC and temperature modulated DSC (TMDSC) by varying the T-c, the heating rate and the crystallization time. DSC and TMDSC curves showed triple melting peaks. The melting behavior indicates that the upper melting peaks are primarily due to the melting of lamellar crystals with different stabilities. A small exothermic curve between the main melting peaks gives a direct evidence of recrystallization. As the T-c increases, the contribution of recrystallization gradually decreases and finally disappears. The Hoffman-Weeks linear plot gave an equilibrium melting temperature of 108.3 degrees C. The kinetic analysis of the spherulific growth rates indicated that a regime II -> III transition occurred at similar to 65 degrees C. (c) 2007 Published by Elsevier Ltd.