Thermal decomposition mechanism of diisopropyl azodicarboxylate and its thermal hazard assessment

Abstract

Thermal decomposition behavior and decomposition mechanism of diisopropyl azodicarboxylate (DIAD) were characterized and analyzed by C80 micro-calorimetery and STA-FTIR-MS system. And thermal hazard of DIAD was assessed by using self-accelerating decomposition temperature (SADT) as the evaluation index. The results show that only one exothermic peak appeared in decomposition process, and that the onset temperature and peak temperature increase with heating rate, whereas the released reaction heat at the heating rates remained approximately constant at 945.67±23.45 kJ/kg. Based on C80 data, the calculated activation energy of DIAD decomposition ranges from 45 kJ/mol to 77 kJ/mol by Friedman method, while the reaction progress in the range of 0.10–0.90. During thermal decomposition process of DIAD, there is only one stage of weight loss, which starts at about 80 ℃, reaches to the maximum rate of weight loss at 138 ℃, and end up at about 150 ℃. The thermal decomposition mechanism of DIAD can be mainly summarized as the route that the CO single bond breaks at first, then CC breaks, and the NN bond breaks subsequently, then the CO bond or the CN bond breaks, final products such as H2O, CO2 etc. appear from further dissociation and oxidation of molecular ionic fragments at last. According to the above-metioned results, the calculated SADT of DIAD is 89.0 ℃ based on Semenov model, when packed in 25kg standard package.