A comparison study on thermal decomposition behavior of poly(l-lactide) with different kinetic models

Abstract

A thermal study of poly(l-lactide) under nitrogen atmosphere has been carried out through thermogravimetric (TG) analysis and differential thermal analysis (DTA) measurements. The experimental data were collected with the heating rates of 2.5 to 30 K min−1 and from ambient temperature up to 750 K. The thermal features were obtained from resultant TG and DTA curves. The results show that the thermal decomposition was mainly in the temperature range of 550–660 K. Kinetic analyses of the mass loss versus temperature data have been performed with four different temperature integral models, including the distributed activation energy model (DAEM), Flynn–Wall–Ozawa, Coats–Redfern, and Tang models. Through the DAEM model, the activation energy distribution function and the relationship between activation energy and pre-exponential factor have been obtained. The activation energy thus obtained at different conversion levels ranges from 91.34 to 107.44 kJ mol−1, and similar results have been produced using the other three models. With these kinetic parameters, the TG curves have been simulated with the above four models by assuming the first-order reaction mechanism, resulting in satisfactory simulation results.