Preparation and Thermal Decomposition Behavior of High-energy Ionic Liquids Based on Ammonium Dinitramide and Amine Nitrates

Abstract

Certain combinations of ammonium dinitramide (ADN, melting point = 93 °C) and additives such as methylamine nitrate (MMAN) (melting point = 110 °C) and urea (melting point = 133 °C), form stable ionic liquids, even below room temperature. These mixtures, referred to as energetic ionic liquid propellants (EILPs), can be highly energetic, and yet are easy to handle. Improving the performance of EILPs will require an understanding of the effects of the additives on the melting point and reaction mechanism for ADN. Therefore, the present work examined the melting point and thermal decomposition and ignition processes for EILPs based on ADN and various amine nitrates. Some EILPs made with low molecular weight amines were found to exhibit a reduced melting point, and high speed photography demonstrated that ignition of these mixtures took place following thermal decomposition of the condensed phase. The thermal behavior and gas evolution for EILPs during heating were assessed by thermal analysis combined with spectrometry and the results showed that the decomposition products were not affected by the specific amine nitrate used in the mixture. The data also suggested that variations in the heat release and reactivity for these mixtures during thermal decomposition can influence the ignitability of the EILPs.