Thermal properties of 1,2,4-triazole-3-one and copper nitrate mixtures

1,2,4-Triazole-3-one (TO) is anticipated to have applications as a high performance alternative gas generating agent, while basic copper nitrate (BCN) is typically used as the oxidizing agent in air bag systems. In order to obtain a better understanding of the thermal properties of TO/BCN mixtures, thermal behavior was investigated using the differential scanning calorimetry. Mixtures of TO with copper, copper oxide, and trihydrated copper nitrate (Cu(NO₃)₂·3H₂O) were also examined for comparison purposes. Samples were prepared at TO/BCN ratios (on a per mass basis) of 10/0, 7/3, 5/5, 3/7, 2/8, 1.6/8.4, 1/9, and 0/10. The endothermic onset temperatures for TO/BCN mixtures were lower than those for either pure TO or pure BCN. TO/BCN mixtures exhibited an initial exothermic peak immediately after an endothermic peak, in the range of 219–234 °C. TO/BCN mixtures with ratios of 3/7, 2/8, 1.6/8.4, and 1/9 displayed a second series of exothermic peaks in the range of 260–300 °C, which appear to result from the oxidation–reduction reaction of previously formed intermediate species with NO₂ and NO generated by unreacted BCN. The TO/CuO mixtures are believed to undergo reaction between molten TO and CuO at approximately 230 °C. In general, the presence of copper was shown to be effective at promoting the decomposition of TO. The reaction between TO and Cu(NO₃)₂·3H₂O seems to be initiated by the melting of Cu(NO₃)₂·3H₂O, following which TO reacts with nitric acid resulting from the dissociation of Cu(NO₃)₂·3H₂O. Overall, the triggering event for the reaction between TO and each of the copper nitrate species is a phase change of one of the two mixture components.