On problems of isoconversion data processing for reactions in Al-rich Al-MoO₃ thermites

Isoconversion processing of thermoanalytical data, while becoming more and more widely used, remains problematic when used indiscriminately. The exothermic reaction in a 4Al·MoO₃ nanocomposite thermite, prepared by arrested reactive milling, was investigated at heating rates ranging from 1 to 40 K/min. The data processing according to a number of traditional isoconversion methods (Kissinger, Friedman, Ozawa-Flynn-Wall), reveals distinct and experimentally reproducible nonlinear regions in the plots of their respective logarithmic function vs. inverse temperature, possibly indicating changes in reaction mechanism over this range of heating rates. More contemporary implementations of isoconversion algorithms give results that are substantially similar. In order to predict kinetic behavior under any heating conditions, especially outside the range of heating rates covered by experiments, a detailed mechanistic model of all involved processes is needed.