Investigation of different thermal analysis techniques to determine the decomposition kinetics of ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane with reduced sensitivity and its cured PBX

Abstract

ε-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is considered the most powerful explosive which has practical application. A reduced sensitivity of CL-20 (RS-CL20) has been obtained by a recrystallization method. In this work, different thermal analysis techniques were investigated to determine the decomposition kinetics RS-CL20 and its polyurethane composite (RS-CL20/HTPB). The polyurethane matrix was based on hydroxyl-terminated polybutadiene (HTPB) and other additives cured by hexamethylene diisocyanate (HMDI). The thermal behavior of the studied samples was studied by Differential Scanning Calorimetry (DSC). The decomposition kinetics were obtained from the measurements of Thermogravimetry analysis (TGA) and Vacuum Stability Test (VST). The isoconversional (model-free) methods which are Kissinger method, Ozawa, Flynn, and Wall (OFW) method and Kissinger–Akahira–Sunose (KAS) method were used. Furthermore, the Advanced Kinetics and Technology Solution (AKTS) software was used to determine the kinetic parameters of the studied samples in order to provide a comparison. It was concluded that the RS-CL20/HTPB has lower decomposition temperature than pure RS-CL20. The polyurethane matrix has obvious effect on decreasing the activation energy of pure RS-CL20. Activation energies calculated by the three different methods are in the same range of AKTS software results. Successfully, VST results were investigated to predict the kinetic parameters of RS-CL20 and its PBX.