The influences of solvents and temperature on polymorphs and thermal stability of ε-HNIW

Polymorphs and thermal stability of hexanitrohexaazaisowurtzitane (HNIW) have attracted much attention of many researchers. ε-HNIW was heated at 70°C for 4 hours in four solvents (water, toluene, heptane and cyclohexane) respectively. The FTIR spectra and DTA curves of the four heated samples were recorded, and compared with the unheated sample. FTIR spectra indicate that the polymorphs of all heated ε-HNIW remain unchanged . DTA curves show that the differences of thermal decomposition peak temperature between the unheated sample and the four heated samples are 0-2. 6°C, 0-2. 6°C, 1-1. 9°C, and 0-2. 5°C at four heating rates of 2, 5, 10 and 20°C/min respectively. In addition, the observed activation energy of the four heated samples has been obtained using both Kissinger method and Ozawa method . The error between the calculated results from these two methods rings ca 2%. It could be concluded that the thermal stability of the four heated samples exhibits no appreciable changes.