Thermal decomposition of energetic materials 82. Correlations of gaseous products with the composition of aliphatic nitrate esters

Abstract

T-Jump/FTIR and T-jump/Raman spectroscopies were used to analyze the gaseous products from six nitrate esters which were rapidly heated (2000°C/s nominal) to set temperatures in the 250 to 500°C range while maintaining a pressure of 5 atm Ar. The compounds studied were nitroglycerin (NG), pentaerythritol tetranitrate (PETN), butanetriol trinitrate (BTTN), trimethanolethane trinitrate (TMETN), triethyleneglycol dinitrate (TEGDN), and bis(nitratomethyl) oxetane (BNMO). The atom balances were determined using all of the gaseous decomposition products based on quantitation by multivariate regression methods. With few exceptions, the oxygen balance of the nitrate ester correlated with the temperature dependence of the products, the CO2/CO ratio, the NO/CO ratio, and the amounts of H2O and total hydrocarbon liberated. The amounts of NO2 and CH2O scaled with the number of -NO2 groups and -CH2O- units in the parent molecule. The relation between the composition of the parent nitrate ester and the gaseous products from pyrolysis is the most straightforward of the various classes of oxidizing energetic functional groups studied to date. Some degree of vaporization of the parent nitrate ester was observed upon flash heating. The IR-active modes of NG and BTTN in the gaseous phase were assigned by calculation of their frequencies by density functional theory in the energy-minimized structure.