Thermal decomposition of energetic materials 74. Volatile metal isocyanates from flash pyrolysis metal-NTO and metal-picrate salts and an application hypothesis

The gaseous products resulting from flash pyrolysis by T-jump/FTIR spectroscopy are described for two classes of energetic metal salts. The first category is the hydrated Li+, Na+, K+, Cu2+, and Pb2+ salts of NTO- (NTO = 3-nitro-1,2,4-triazol-5-one), and the second is the Li+, Na+, K+, Rb+, Cs+, Co2+, and Ni2+ salts of picric acid (PA). The atom balance is generally better with the NTO salts. The characteristics of the evolution of H2O were obtained for the Li+, Na+, and K+ salts of NTO at a heating rate of about 800 degrees C/s. All of these salts liberate volatile metal compounds, although the quantity is smaller in the case of the most energetic salts, e.g., Cu(NTO)(2)(H2O)(4) and the picrates. The Group 1 metal salts of both NTO and PA produce metal isocyanate vapor (MNCO) as monomers or very small aggregates. Fb(NTO)(2)(H2O) appears to produce more than one volatile metal-containing compound. An application of these volatile metal isocyanates is hypothesized to be their continued reaction to form metal oxide particles that might produce subsequent damping of high-frequency acoustic oscillations in solid rocket motors. (C) 2000 by The Combustion Institute.