The thermal decomposition of RDX at temperatures below the melting point. I. Comments on the mechanism

Abstract

Two mechanisms have recently been proposed to explain the behaviour of the initial rate of decomposition of RDX, with change in sample geometry. These are (i)that the decomposition proceeds by concurrent gas and liquid phase reactions, and (ii) that gaseous decomposition products influence the rate of decomposition of undecomposed RDX in the condensed phase. In this paper it is concluded that mechanism (ii) is the more probable when the reaction is carried out in the presence of nitrogen.

How does low temperature coupled with different pressures affect initiation mechanisms and subsequent decompositions in nitramine explosive HMX?

“…Initial decomposition mechanism and pressures (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). It is seen that the initial decomposition mechanism of HMX is unimolecular C-H bond breaking.…”

“…Fig. However, at a high temperature (873 K), the first C-N bond breaking occurred more easily than at a low temperature, and this could occur before the breaking of all the N-N bonds and (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). At low temperatures (534 and 608 K) and high pressures (1-20 GPa), the energy barrier of the first C-N bond breaking is too high to occur directly just after the initial decomposition.…”

“…Like temperature, pressure also affects the thermal decomposition of energetic materials, [10][11][12][13][14][15][16][17][18][19][20][21][22] either directly by influencing its kinetics and mechanism 11,22 or through its effect on the chemical interaction of the primary fragments or on the reaction of the decomposition products with the starting material. [11][12][13][14] For example, an increase in induced pressure produces a decrease in the decomposition reaction rate of solid HMX and RDX, 10,11,22 an increase in decomposition rate of liquid RDX, 10 and a dramatic change in the reaction mechanism for the thermal decomposition of nitromethane above 4 GPa.…”

“…The ratios (d/d 0 ) of the number of unreacted HMX molecules, unbroken C-H bonds, and unbroken N-NO 2 bonds at the simulation end and beginning under coupling effects of different temperatures (534-873 K) and pressures(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20).…”

Development of Novel Decontamination and Inerting Techniques for Explosives Contaminated Facilities. Phase 1. Identification and Evaluation of Novel Decontamination Concepts. Volume 1

“…strated by a slow-rate (induction) period during the initial stages of thermal decomposition. As the products increase in concentration, the rate of reaction increases (Batten, 1969). Among the products listed in Table 8, N20, HCN, CH 2 0 and N-hydroxy-N-methylformamide, have been reported to catalyze the reaction whereas N02 and H20 have been reported to inhibit the reaction.…”