Thermal behavior of ammonium dinitramide and amine nitrate mixtures

This paper focuses on the thermal behavior of mixtures of ammonium dinitramide (ADN) and amine nitrates. Because some mixtures of ADN and amine nitrate exhibit low melting points and high-energy content, they represent potential liquid propellants for spacecraft. This study focused on the melting behavior and thermal-decomposition mechanisms in the condensed phase of ADN/amine nitrate mixtures during heating. We measured the melting point and exothermal behavior during constant-rate heating using differential scanning calorimetry and performed thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS) to analyze the thermal behavior and evolved gases of ADN/amine nitrate mixtures during simultaneous heating to investigate their reaction mechanisms. Results showed that the melting point of ADN was significantly lowered upon the addition of amine nitrate with relatively low molecular volume and low melting point. TG-DTA-MS results showed that the onset temperature of the thermal decomposition of ADN/amine nitrates was similar to that of pure ADN. Furthermore, during thermal decomposition in the condensed phase, ADN produced highly acidic products that promoted exothermic reactions, and we observed the nitration and nitrosation of amines from the dissociation of amine nitrates.