Thermal Behavior, Nonisothermal Decomposition Reaction Kinetics of Mixed Ester Double-base Gun Propellants

Abstract

Abstract The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate(TEGDN) and nitroglycerin(NG) were investigated by thermogravimetry(TG) and differential thermogravimetry(DTG), and differential scanning calorimetry(DSC) under the high-pressure dynamic ambience. The results show that the thermal decomposition processes of the mixed nitric ester gun propellants have two mass-loss stages. Nitric ester evaporates and decomposes in the first stage, and nitrocellulose and centralite II(C2) decompose in the second stage. The mass loss, the DTG peak points, and the terminated temperatures of the two stages are changeable with the difference of the mass ratio of TEGDN to NG. There is only one obvious exothermic peak in the DSC curves under the different pressures. With the increase in the furnace pressure, the peak temperature decreases, and the decomposition heat increases. With the increase in the content of TEGDN, the decomposition heat decreases at 0.1 MPa and rises at high pressure. The variety of mass ratio of TEGDN to NG makes few effect on the exothermic peak temperatures in the DSC curves at different pressures. The kinetic equation of the main exothermal decomposition reaction of the gun propellant TG0601 was determined as: dα/dt=1021.59(1-α)3e-2.60 × 104/T. The reaction mechanism of the process can be classified as chemical reaction. The critical temperatures of the thermal explosion(Tbe and Tbp) obtained from the onset temperature(Te) and the peak temperature(Tp) are 456.46 and 473.40 K, respectively. ΔS‡, ΔH‡, and ΔG‡ of the decomposition reaction are 163.57 J·mol-1·K-1, 209.54 kJ·mol-1, and 133.55 kJ·mol-1, respectively.