Thermal behaviour kinetic study of dihydroglyoxime and dichloroglyoxime

Glyoxime derivatives have increasingly gained attention because of their potential for generation of energetic materials. In this paper, the thermal behaviours of dihydroglyoxime (DHG) and dichloroglyoxime (DCG) in a nitrogen atmosphere were studied under non-isothermal conditions by thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. The results showed that the decomposition of DCG occurs in two continuous steps, in the 160-230 degrees C temperature range. Each thermal degradation stage for DCG results an exothermic peak in the DSC curve. On the other hand, applying TG-DSC techniques indicates that DHG sublimates about 178 degrees C before it decomposes. Also, the influence of the different heating rates such as 5, 10, 15 and 20 degrees C min(-1) on the thermal behaviour of both compounds was investigated. The results of DSC experiments indicate that the peak temperature of DCG decomposition and sublimation temperature for DHG were increased, as the heating rate was increased. The kinetic parameters such as activation energy and pre-exponential factor for each compound were found by means of the Kissinger method and were verified by the Ozawa-Flynn-Wall method. Based on the values of activation energy obtained by the Kissinger method, the first stage of DCG decomposition has an activation energy about 100 U mol(-1) and the sublimation process for DHG has an activation energy about 259 U mol(-1). Finally, the thermodynamic parameters (Delta G(#), Delta H-# and Delta S-#) for decomposition of DCG and sublimation of DAG were determined. (c) 2007 Elsevier B.V. All rights reserved.