Mj. Rossi et al., THE THERMAL-DECOMPOSITION OF THE NEW ENERGETIC MATERIAL AMMONIUMDINITRAMIDE (NH4N(NO2)2) IN RELATION TO NITRAMIDE (NH2NO2) AND NH4NO3, International journal of chemical kinetics, 25(7), 1993, pp. 549-570
This qualitative study examines the response of the novel energetic ma
terial ammonium dinitramide (ADN), NH4N(NO2)2, to thermal stress under
low heating rate conditions in a new experimental apparatus. It invol
ved a combination of residual gas mass spectrometry and FTIR absorptio
n spectroscopy of a thin cryogenic condensate film resulting from depo
sition of ADN pyrolysis products on a KCl window. The results of ADN p
yrolysis were compared under similar conditions with the behavior of N
H4NO3 and NH2NO2 (nitramide), which served as reference materials. NH4
NO3 decomposes into HNO3 and NH3 at 182-degrees-C and is regenerated o
n the cold cryostat surface. HNO3 undergoes presumably heterogeneous l
oss to a minor extent such that the condensed film of NH4NO3 contains
occluded NH3. Nitramide undergoes efficient heterogeneous decompositio
n to N2O and H2O even at ambient temperature so that pyrolysis experim
ents at higher temperatures were not possible. However, the presence o
f nitramide can be monitored by mass spectrometry at its molecular ion
(m/e 62). ADN pyrolysis is dominated by decomposition into NH3 and HN
(NO2)2 (HDN) in analogy to NH4NO3, with a maximum rate of decompositio
n under our conditions at approximately 155-degrees-C. The two vapor p
hase components regenerate ADN on the cold cryostat surface in additio
n to deposition of the pure acid HDN and H2O. Condensed phase HDN is f
ound to be stable for indefinite periods of time at ambient temperatur
e and vacuum conditions, whereas fast heterogeneous decomposition of H
DN at higher temperature leads to N2O and HNO3. The HNO3 then undergoe
s fast (heterogeneous) decomposition in some experiments. Gas phase HD
N also undergoes fast heterogeneous decomposition to NO and other prod
ucts, probably on the internal surface (ca. 60-degrees-C) of the vacuu
m chamber before mass spectrometric detection.