Chemical mechanisms and kinetics are described for the surface reaction zone of materials of interest in solid rocket propellants. The technique used is flash thermolysis of films by T-jump-Fourier transform infrared spectroscopy. The potential for burn rate modification by a wide variety of related nitrogen heterocyclics was uncovered. The kinetics of decomposition of HMX, RDX and NTO were evaluated and critically analyzed. It was found that a kinetic compensation effect exists. Lower values of the activation energy for NTO were all shown to result from sublimation kinetics rather than decomposition kinetics. A three-stage reaction mechanism for HMX and RDX in the condensed phase was proposed which involves two competitive decomposition reactions and one strongly exothermic reaction. This model is now being adopted in most combustion models of nitramines. The decomposition kinetics and mechanism of HNF were determined for the first time at flash heating conditions. The kinetics of product evolution was determined for HTPB at combustion temperatures. It was found that desorption kinetics rather than bulk-phase decomposition kinetics control the rate of volatilization at temperatures above about 500 deg C.
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