Kinetic thermal decomposition studies of thalidomide under non-isothermal and isothermal conditions

Thermogravimetric analysis (TG) was used to investigate kinetic thermal decomposition process of thalidomide under non-isothermal and isothermal conditions. For the isothermal treatment, a methodology based on multilayer perceptron neural networks was adopted using four isothermal experimental data. These temperatures were chosen once they are near to the most important loss of mass of the material. Fifteen well-established models for solid thermal decomposition were used in the network to describe the process. The contraction models were selected by the network as a preferable set as they presented small residual error to fit the data. The neural network architecture allows quantifying the contribution of each model in the process description and also corrects the kinetic functions. Nitrogen atmosphere was used, and the experiments were performed at 293, 304, 314 and 324 degrees C. In the non-isothermal analysis, the activation energy was calculated through Friedman, Vyazovkin and Kissinger-Akahira-Sunose methods. For these experiments, N-2 atmosphere was also used at four heating rates: 2.5, 5.0, 10 and 20 degrees C min(-1). The activation energy was calculated as 98-108 kJ mol(-1) for all the methods. The results were compared and analyzed to predict thermal decomposition for the medicines.