Synthesis, characterization and thermal degradation kinetics of Copolyesters

The copolymer of lactic acid, ethylene glycol and succinic acid (cop1) was synthesized by the condensation process of lactic acid, succinic acid and ethylene glycol. The copolymer was then characterized by FTIR, 1 HNMR, 13 CNMR, DSC, TGA/DTA; the (cop1) was analyzed also for various properties such as acid value, number average molecular weight, etc. The thermal degradation kinetics was investigated for the (cop1) by dynamic thermogravimetry, in a nitrogen atmosphere, at the temperature range of 25 °C to 500 °C, at constant nominal heating rates of 10, 15 and 20 °C/min, respectively. Two distinct mass change stages in the thermogravimetric analysis curves indicated that the degradation of (cop1) may be attributed to two reactions. The Kissinger, Friedman and Flynn-Ozawa-Wall methods were developed, the corresponding activation energies, frequency factors and reaction orders of the two reactions were determined. We proposed the thermal degradation mechanism of the copolymer.