Thermal decomposition of energetic materials 73: the identity and temperature dependence of “minor” products from flash-heated RDX

Abstract

The approximate identity and temperature dependence of volatile “minor” products (defined as <4% mole fraction) from thermal decomposition of hexahydro-1,3,5-trinitro- s-triazine, RDX, were determined by heating a film at 800°C/sec under 4 atm Ar. The IR spectra from pyrolysis at specific temperatures in the 265–325°C range were resolved by multivariate regression, which enabled the major products to be removed and the minor products to be uncovered. The gaseous phase contained hexahydro-1-nitroso-3,5-dinitro- s-triazine (MRDX), a triazine modeled as s-triazine (TAZN), C-hydroxyl-N-methylformamide (HMFA), and both RDX vapor (RDXv) and aerosol (RDXs). The behaviors of HONO and HNCO are also discussed because they have mole fractions below 4%. The concentrations of MRDX, HMFA, RDXv, and RDXs decrease with increasing temperature. HONO and TAZN maintain relatively constant concentrations. HMFA and HNCO are oppositely correlated, suggesting that HNCO comes from HMFA. The relation between this work and previous studies of slower decomposition of RDX and on quenched burning of RDX-containing propellants is discussed in an attempt to unify the description of amides and nitrosoamines in the RDX decomposition scheme over a wide range of heating rates.