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The thermal stability of 3,6-dihydrazino-1,2,4,5-tetrazine (DHT) and 3,6-bis(1H-1,2,3,4-tetrazol-5-ylimino)-1,2,4,5-tetrazine (BTATz) have been examined by isothermal and nonisothermal methods. The research conducted allow considering that the first stage of DHT decomposition is an unique, from viewpoint of thermal decomposition, redox process, in which tetrazine ring is reduced by hydrazine group forming diaminodihydrotetrazine and molecular nitrogen. In the case of BTATz, the decomposition begins with less thermostable tetrazole fragments, which captures the tetrazine ring also. The presence of preliminary reactions of isomerization during tetrazole ring decomposition is the reason for the large observable activation energy of decomposition (240.6 kJ/mol or 57.5 kcal/mol) in the temperature interval 250–334 °C. In the combustion wave at higher temperatures, the activation energy of BTATz decomposition has considerably lower value (128.4 kJ/mol or 30.7 kcal/mol), which is close to theoretically calculated one. Burning characteristics of DHT and BTATz have been investigated. The temperature distribution in the combustion waves of DHT and BTATz have been measured at low pressures, which allows obtaining the surface temperature dependence vs. pressure. The research conducted allow considering that the burning of investigated compounds controls by a combustion model with leading reaction in the condensed phase. |
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