Model free isoconversional procedure for evaluating the effective activation energy values of thermally stimulated processes in dinitroimidazoles.

Abstract

The decomposition kinetics of 1,4-dinitroimidazole, 2,4-dinitroimidazole, and N-methyl-2,4-dinitroimidazole have been investigated using thermogravimetry-differential thermal analysis technique under N2 atmosphere at the flow rate 100 cm(3)/min. The Flynn-Wall-Ozawa method and the Friedman method were used for the estimation of the effective activation energy values. These model free isoconversional kinetic methods showed variation in the calculated values due to the approximation of temperature integral used in the derivations of the kinetic equations. The model compounds were decomposed by multi-step kinetics evident from the nonlinear relationship of the effective activation energy values with the conversion rate. Three different reaction pathways namely NO2 elimination, NO elimination, and HONO elimination are expected to play crucial role in the decomposition of nitroimidazoles. The model dinitroimidazoles represent different decomposition kinetics, and the reaction pathways the NO2 elimination, and NO elimination compete with each other for the decomposition mechanism. The present study is certainly helpful in understanding the decomposition kinetics, and dynamics of substituted nitroimidazoles to be used for fuel, and explosive applications.