Compatibility of ADN with components used in formulations

ADN (ammonium dinitramide) is seen as possible replacement oxidizer for ammonium perchlorate in rocket propellant formulations. The advantage of ADN is beside its good oxygen balance no content of chlorine and to give signature reduced plume of smoke of the rocket motor. The disadvantage of ADN is twofold: its lower intrinsic thermal stability compared to ammonium perchlorate together with autocatalytic decomposition and its high reactivity already at ambient temperatures with some standard ingredients of rocket propellants. The stability of ADN can be sufficiently improved by addition of stabilizers, which suppress the autocatalytic decomposition. But the high reactivity of ADN causes in part severe compatibility problems and the achievement of acceptable use times of ADN containing formulations is questioned therefore. The solution for this is a careful selection of ingredients based on compatibility determination. ADN is still a not well-known substance with respect to its compatibility. Its reactivity as function of temperature and time should be determined therefore with several measurement methods which probe the test mixture in different ways. Reactivity means the excess reaction induced by the two components in contact over the sum of the reaction parts of the two components alone. This excess reaction is expressed as excess conversion, for which limit values have to be defined. The used measurement methods are mass loss, gas generation and heat generation. They probe the substances by split off reaction gases and by the net sum of the heats of reactions. Mass loss is complementary to gas generation but it has a principal advantage over gas generation in getting the excess conversion. On the compatibility of ADN with HMX, RDX, FOX 7, GAP diol, HTPB, DOA, nitrocellulose (NC), polyGlyn and polyNimmo is reported.