Mechanisms of Nitramine Decomposition: Very Low-Pressure Pyrolysis of HMX and Dimethylnitramine. Final Report.

摘要

The very low-pressure pyrolysis (VLPP) of cyclotetramethylenetetranitramine (HMX) and dimethylnitramine have been studied over the temperature ranges 530 to 645 exp 0 K and 550 to 840 exp 0 K, respectively. High pressure limit Arrhenius parameters for HONO elimination and N-NO sub 2 bond scission in dimethylnitramine have been determined to be log k(sec exp -1 ) = 12.4 +- 0.8 - (37 +- 1.8)/2.3 RT and log k(sec exp -1 ) = 16.5 +- 0.8 - (48.5 +- 1.8)/2.3 RT, respectively. Use of the dimethylnitramine decomposition parameters as models for HMX decomposition suggests that HONO elimination and N-NO sub 2 bond scission should have equal rates at about 600 exp 0 K. Above this temperature, N-NO sub 2 bond scission will become increasingly predominant. The observed temperature dependence of HMX decomposition is consistent with an activation energy less than or equal to 40 kcal/mole, but the data are too scattered to completely rule out the 45.50 kcal/mole which would signify initial N-NO sub 2 bond scission. The decomposition of HMX yields m/e 46 as a major initial product mass, consistent with either pathway, but not consistent with either concerted or stepwise depolymerization as the probable initial step(s) in HMX decomposition. (ERA citation 04:055463)