Keywords solid propellant, ammonium dinitramide, ADN, HTPB, performance, compability, formulation, burn rate
Abstract The aim of this work is to perform an initial evaluation of ammonium dinitramide,
ADN, as substitute for ammonium perchlorate, AP, in solid rocket propellants for large
space launch boosters.
This final report includes performance evaluation, compatibility and curing
assessments, propellants formulation and determination of ballistic properties.
The results show that the theoretical specific impulse increases from 262 s to 270 s by
replacing AP with the same volume ADN in a typical HTPB/Al-based formulation.
ADN is found to be chemically compatible with HTPB. However, ADN seems to
accelerate the oxidative degradation of HTPB and thus a suitable antioxidant is
required. ADN/HTPB/Al-based propellants have been formulated and cured
successfully using isocyanates. The formulations were found to be thermally stable.
Ballistic properties were determined using a strand burner. ADN/Al/HTPB propellant
with a solid loading of 80 % had a burn rate of 12.8 mm/s at 6 MPa and a pressure
exponent of 0.9. The pressure exponent is high. However, no burn rate modifiers or
ballistic additives were used. This encourages continued evaluation.
The report also includes information on how to handle ADN with respect to
transportation, toxicity and hazard properties.
This work was performed on NASA contract NNC09CA11C.