Structure-Thermolysis Relationships for Energetic Materials

Abstract

ABSTRACT.Rapid thermal decomposition studies (dT/dt > 70°C/sec) under static pressures of 1-1000 psi provide new insight into the behavior of ener'getic materials in the condensed phase. The connection between the parent molecular structure of nitramines and the tendency to liberate N02, HONO, NO, N20, CH20, HCN, and hydrocarbons is discussed. Many important differences are found between the resul ts of gas phase decomposi tion studies and those herein for the condensed phase which points out the hazards of transferring gas phase notions to the condensed phase.In addition to nitramines, selected correlations for C-N0 2 , O-N02' N-NO, azide, furazan, and furoxan containing compounds, energetic metal complexes, and nitrate salts are presented. The effect of applied pressure and the thermolysis of mixtures are addressed.Various solid phase phenomena are described in the context of energetic mater ials. Some application of these physicochemical phenomena to explosives and propellant ignition and combustion are discussed.

New Propellant Component, Part I. Study of 4,6-Dinitroamino-1,3,5-Triazine-2(1 H)-One (DNAM)

“…It is of interest to place the thermolysis of DNAM in the perspective of other works carried out on the decomposition of nitramines (25)(26)(27)(28)(29) . It is generally accepted that nitramine functional group is predominant in the early decomposition stages.…”

“…It is generally accepted that nitramine functional group is predominant in the early decomposition stages. It is the main source of highly reactive species as, among others, nitrogen oxides such as NO 2 and=or N 2 O, whose relative amounts are dependent on factors like temperature, pressure, and structure of the starting nitramine (25,29) . These reactive species are crucial as reaction proceeds, namely because they are the only oxygen suppliers when no other (external) oxygen source is available.…”

“…Our kinetic analysis results are qualitatively consistent within this framework of the thermolysis of nitramines. In the light of experimental evidences showing that primary nitramines are strong generators of N 2 O when compared with secondary ones (29) , it is our belief that the primary nitramine groups in DNAM would preferentially generate N 2 O in the early decomposition stages. But the first species actually formed in the reaction interface remain to be identified, and a deeper research on the decomposition of DNAM will be necessary.…”

Kinetics and mechanisms of thermal decomposition of nitroaromatic explosives

“…These reactions involve exothermic oxidation and reduction that lead to lower molecular weight and thermodynamically stable gaseous products. While much is known about the related kinetics and thermochemistry of hydrocarbon/air flames (References 231-233) and nitrogen chemistry in combustion (Reference 234), the processes by which large, bulk phase energetic molecules thermolyze to form the reactants for the high temperature flame is a challenging area of research (References 41, 107,217).…”

“…Release of a large amount of heat early in the decomposition reaction scheme near the burning surface produces a high burn rate for the material. 216,217 The initial decomposition chemistry when an azide group is present on a nitroaromatic backbone appears to be straightforward on the basis of the current knowledge of these compounds. However, the explosive characteristics of these compounds are essentially unknown.…”