Thermal decomposition of RDX

Phys., 122, 054502 (2005). Thermal Decomposition of RDX from Reactive Molecular Dynamics. 

Through the use of simultaneous thermogravimetry modulated beam mass spectrometry, optical microscopy, hot-stage time-lapsed microscopy, and scanning electron microscopy measurements, the physical and chemical processes that control the thermal decomposition of RDX 9 below its melting point (160-189 °C) have been identified (Scheme 17) <2005PCA11236>. 

Strachan A et al (2005) Thermal decomposition of RDX from reactive molecular dynamics. J Chem Phys 122(5) 054502... 

Investigation of the Thermal Decomposition of RDX Chemical Physics Letters 64, 307-310. 

Two small ruby chips used as pressure sensors are visible, one near the center of the sample and the other adjacent to the gasket edge. The sample is homogeneous. The products of decomposition exhibit interesting behavior and require further discussion. Thermal decomposition of RDX at 4.0 GPa and 516 K produced the products shown... 

Cook (Ref 1), in describing thermal decomposition of some HE s conducted in the quartz spring apparatus (described in Ref 1, p 175 and shown there in Figs 8.1a 8.1b), stated that PETN, RDX, Tetryl and to a small extent TNT decomposed autocatalyti-cally. EDNA followed the first-order decomposition law only until about 5% of the explosive had decomposed and then the reaction stabilized. The term autostabilization was applied here on the supposition that one of the condensed decomposition products of EDNA which accumulated in the explosive apparently tended to stabilize the bulk of expl and thus slow down the decomposition. After about 10% of the expl had decompd, however, the "autocatalysis developed. 

Thermal decomposition of pure explosives such as primary explosives lead azide, lead styphnate, mercury fulminate etc. [35], monomethylamine nitrate [36] and explosive mixtures RDX + HMX mixtures [37]. 

CA 43, 405 (1949) (Thermal decompn of PETN, NG, Ethylenediamine Dinitrate AN) l6)Ibid, TrFaradSoc 45, 85-93 (1949) CA 43, 5187 (1949) (Thermal decompn of RDX HMX) 17)A. J.B.Robertson, Third Symposium on Combustion and Flame and Explosion Phenomena , Williams Wilkins, Baltimore, Md (1949), 545 -51 (Thermal initiation of expln in liquid expls) I8)S. Livingston W.R.Tomlinson Jr, Fundamental Research on Explosives. Decomposition of Explosives at Elevated Temperatures , PAIR 1737 (1949) 19)Anon, Artillery Ammunition ,... 

We examined the thermal decomposition of a number of nitramines in dilute solution and in the melt phase. The nitramines included acyclic dialkyl mononitramines, where the dialkyls were methyl, ethyl, propyl and isopropyl cyclic mononitramines (N-nitro-pipeiidine and N-nitropyrrolidine) and cycle multifunctional nitramines (N-dinitropiperazhe l,3-dinitro-l,3-diazacyclo-pentane l,3-dinitro-l,3-diazacycbhexane RDX and HMX). For all nitramines, the predominant condensed-phase product was the nitrosamine though the amount formed depending on the nitramine and the phase of the thermolysis. The common trigger in the decompositions was N-N02 ho mo lysis, but the fate of the resultant amine radical depended on the phase. In solution the radical was stabilized sufficiently so that it resisted further decomposition and, instead, reacted with NO to form nitrosamine. In vapor or condensed phase, the amine radical underwent further reaction therefore,... 

J.C. Hoffsomer, D.J. Glover, Thermal Decomposition of 1,3,5-Trinitro-l,3,5-Triazine (RDX) Kinetics of Nitroso Intermediates Formation, Combust. Flame, 59 (1985) 303. 

Mass spectra of the important explosives RDX, HMX, TNT, TNB and Tetryl were first briefly reported by Meyer (Ref 34) and later investigated in greater detail with high resolution and labeling techniques by Bulusu et al (Ref 45). Mass spectrometric studies of the photodecomposition of labeled dimethyl-nitramine (Ref 56) and the thermal decomposition of HMX and RDX (Refs 27 31) illustrate the application of these techniques to studies of reaction mechanism and bond dissociation processes. Nitroguanidines have only recently been investigated by Beynon (Ref 35)... 

Equilibrium MD simulations can provide valuable information about the thermal decomposition of energetic materials and can also enable the exploration of phenomena with time-scales much longer than in shockwaves. As an example, we studied the decomposition and subsequent reactions of RDX under various temperatmes (between T = 1200 K and T = 3000 K) and densities (at low density, 0.21 g/cm near normal density, 1.68 g/cm and under compression, 2.11 g/cm ), using MD with RDX interactions given by the reactive potential ReaxFF. 

We also made molecular-dynamic simulation of thermal decomposition of some individual energetic materials, including RDX, at extremely high temperatures [93,94]. It turned out that the primary fragmentation mechanism at these conditions is entirely different from the low-temperature variant. In the case of the RDX unimolecular decomposition, it can be mentioned that elimination of NO2 group by homolysis of one N-N bond is observed for all reaction conditions whereas perhydrotriazine ring fission (depolymerization to... 

Because the technique relies on thermal decomposition of nitro-containing explosives, and no prior chromatographic separation is performed, no chemical information of the studied material is obtained. Currently, the unit will alarm on compounds such as RDX, PETN, TNT, urea nitrate, ammonium nitrate, nitroglycerine, EGDN and DMNB. 

Studies of the formation of HONO from secondary nitramines, R2N(N02) (R = -CH2-), illustrate an advance made possible by Fast Thermolysis/FTTR methods [I8]. HONO has been considered to be an important intermediate in the thermal decomposition of nitramines [19], but, because of its reactivity, was proposed based on indirect evidence [20,21] until this Fast Thermolysis/FTIR technique was applied. Cis- and trans-HONO are both present in the IR spectrum of the gas from RDX (see the PQR pair at 700-900 cm in Figure 2), but as shown in Figure 3, HONO is transient under the conditions of the experiment. The initial concentration most closely reflects its relationship to the composition of the parent molecule. Figure 4 shows the quantity of HONO as a percentage of the initial gas products for various nitramines [18] versus the H/NO2 ratio in the parent molecule. The general trend suggests that HONO arises from adventitious bimolecular encounters of H and N02 radicals in the condensed phase [18], rather than concerted decomposition of the 4- and 5-center unimolecular intermediates shown below that may contribute in the gas phase [22]. 

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