Investigation on Continuous Specific Heat Capacities, Thermodynamic Properties and Thermal Decomposition Kinetics of Micro-sized and Nano-sized RDX

In order to analyze the thermal properties of RDX with different particles sizes, the continuous specific heat capacities of micro-sized and nano-sized RDX with particle size of 1μm, 500nm and 100nm were determined by the μSC calorimetry method at the temperature of 288-353K. The specific heat capacity curves were fitted to achieve the equation of Cp, and the thermodynamic properties of RDX with different particle sizes were calculated based on the thermodynamic law. The thermal decomposition behaviors of RDX with different particle sizes were investigated by DSC and their decomposition kinetic paramelers were calculated according to the Kissinger's method. The results show that the μSC calorimetry method is favorable for the measurement of specific heat capacity with simplicity and high accuracy. For the micro-sized RDX particles, the specific heat capacity, entropy and enthalpy increase with the increase in temperature, whereas the Gibbs free energy shows an opposite behavior. Moreover, the enthalpy and Gibbs free energy of RDX reduce with the decrease in particle sizes, but the entropy increases with the decrease in sizes. Compared with the micro-sized RDX, the changes occurred to entropy and Gibbs free energy of nano-sized RDX are relatively small, which is believed to originate from their smaller particle size. Although kinetic parameters of the melting and decomposition processes of micro-sized and nano-sized RDX are different, they all obey the "dynamic compensation effect" rule. © 2019, Editorial Board of Journal of Explosives & Propellants. All right reserved.