Thermal analysis of the reaction of a mixture of ammonium dinitramide and hydroxyethylhydrazinium nitrate

The thermal analysis of a mixture of ammonium dinitramide (ADN) and 2-hydroxyethylhydrazinium-hydroxyethylhydrazinium nitrate (HEHN) (i.e., ADN/HEHN) was conducted using differential scanning calorimetry (DSC) and thermogravimetry (TG)-differential thermal analysis (DTA). Furthermore, evolved gas analysis, such as mass spectrometry (MS) and Fourier transform infrared spectroscopy (IR), and composition analysis of the liquid phase via attenuated total reflection (ATR)-IR-IR were employed to understand the mechanism of thermal decomposition for this mixture. The DSC results showed that ADN/ HEHN exhibited an exotherm with two overlapping peaks; the first and second peaks were attributed to the decompositions of ADN and HEHN, respectively. The second peak top temperature of the exotherm of the mixture was lower than that of HEHN, and the heat value of the mixture exceeded that of each of the individual substances. This indicated that ADN accelerated the decomposition of HEHN and reacted well with it. The TG-DSC-IR-DSC-IR and TG-DTA-MS-DTA-MS results showed that a second exotherm was observed in the reaction of the individual substances and decomposition products of ADN/HEHN. The second exotherm produced more CO2 2 and H2O 2 O than the pyrolysis of HEHN. The ATR-IR-IR results showed that monoethanolamine nitrate (MEAN), which is highly reactive with ADN, was formed from the pyrolysis of HEHN. Thus, the results suggest that the high reactivity of ADN and HEHN was due to the reaction between MEAN (formed from the decomposition of HEHN accelerated by ADN) and NO2 2 (generated from ADN).