THERMAL-DECOMPOSITION OF ENERGETIC MATERIALS .63. SURFACE-REACTION ZONE CHEMISTRY OF SIMULATED BURNING 1,3,5,5-TETRANITROHEXAHYDROPYRIMIDINE (DNNC OR TNDA) COMPARED TO RDX

The oxidizers 1,3,5,5-tetranitrohexahydropyrimidine (DNNC or TNDA) and RDX are found to have similar burn rates in a strand burner operating at 20-250 atm. These strand burner data extrapolate well to the regression rates obtained from high-rate weight-loss measurements by SMATCH/FTIR spectroscopy on films of DNNC and RDX of about 45 mum thickness. This observation supports the use of rapid pyrolysis of films coupled with spectral diagnostics to determine chemical details about the surface reaction zone of burning DNNC and RDX. By using T-jump/FTIR spectroscopy, the gas product concentrations from DNNC rapidly decomposing at 220-degrees-300-degrees-C reveal that DNNC and RDX thermolyze by different routes. Decomposition reactions that form NO are especially important for DNNC, but this does not affect the primary flame zone. The primary flame zone of both DNNC and RDX appears to be dominated by the reaction of CH2O and NO2, which contributes to the similarity of their burn rates.