A Review of the Thermal Decomposition Pathways in RDX, HMX and Other Closely Related Cyclic Nitramines.

Abstract

Understanding the complex physicochemical processes involved in the combustion and decomposition of energetic materials is essential to the development of reliable models for the performance. stability and hazards analysis of propellants and explosives and to provide a basis for improvement of ignition and sensitivity properties of their formulations. Since the nitramines RDX and HMX are important materials as propellants and explosives, we have undertaken a comprehensive; in-depth study, over the years, of their thermal decomposition kinetics and mechanisms using unusual sophisticated techniques, namely, simultaneous thermogravimetric modulated beam mass sf.ectrometry  (STMBMS). time-of-flight velocity spectra analysis, isotope labeling (ISN, (3e, 2H and ( 0), isotope scrambling techniques and deuterium kinetic isotope effects (DKIE). In this paper, the results of the condensed and gas phase decomposition studies of RDX and HMX are reviewed in terms of the reaction pathways, bond-breaking steps and some bond-forming reactions. A comparison is made with the decomposition of six other cyclic nitramines and the common and contrasting modes of decomposition are highlighted. In particular, it is shown that the formation of a mononitroso analogue from RDX and HMX, respectively, as intermediates, represents an important thermal degradation pathway in each and probably also in four other nitramines studied. The cyclic nitramine
1.3,5-trinitro-I,3.5-triaza-cyclo-heptane exhibits the potential to be a new useful nitramine with valuable application.