Initial Reaction Steps in the Condensed-Phase Decomposition of Propellants
Understanding the reaction mechanisms for the decomposition of energetic materials in the condensed phase is critical to our development of detailed kinetic models of propellant combustion. To date, the reaction mechanisms in the condensed phase have been represented by global, reactions. The detailed elementary reactions subsequent to the initial NO{sub 2} bond scissioning are not known. Using quantum chemical calculations, we have investigated the possible early steps in the decomposition of energetic materials that can occur in the condensed phase. We have used methylnitrate, methylnitramine, and nitroethane as prototypes for O-NO{sub 2}, N-NO{sub 2} and C-NO{sub 2} nitro compounds. We find the energetic radicals formed from the initial NO{sub 2} bond scissioning can be converted to unsaturated non-radical intermediates as an alternative to the unzipping of the energetic radical. We propose a new, prompt oxidation mechanism in which the trapped HONO can add back onto the energetic molecule. This produces oxidation products in the condensed phase that normally would not be produced until much later in the flame. We have shown that this prompt oxidation mechanism is a general feature of both nitramines and nitrate esters. The resulting HONO formed by the H-atom abstraction will be strongly influenced by the cage effect of the condensed phase. The applicability of this mechanism is demonstrated for decomposition of ethylnitrate, illustrating the importance of the cage effect in enabling this mechanism to occur at low temperatures.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15007535
- Report Number(s):
- UCRL-JC-146559; TRN: US200419%%71
- Resource Relation:
- Journal Volume: 29; Journal Issue: 2; Conference: 29th International Symposium on Combustion, Sapporo (JP), 07/21/2002--07/26/2002; Other Information: PBD: 11 Dec 2001
- Country of Publication:
- United States
- Language:
- English
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