Effect of NQ content on the thermal decomposition of nitroguanidine propellant using isoconversional methods

Abstract

The effect of nitroguanidine (NQ) content on thermal decomposition of nitroguanidine propellants was studied using three nitroguanidine propellants with different NQ contents (10%, 30% and 47%) and one double-base propellant. The thermal decomposition was investigated by high-pressure differential scanning calorimetry. Results show that heat flow curves of the four tested formulations all had only one exothermic peak, and as the heating rate increased, both the peak temperature and the decomposition heat increased. Calculation of thermal decomposition kinetics of the propellants was performed using multiple-temperature programs. Increased NQ contents changed the mechanism of thermal decomposition of the propellant. The reaction mechanism is chemical reaction for the double-base propellant and the 47%-NQ propellant, phase boundary reaction for the 30%-NQ propellant and nucleation and growth for the 10%-NQ propellant. The thermodynamic parameters indicate that, as the NQ content increases, the critical temperature (Tbe) of thermal explosion of the propellants increases, which leads to higher thermal stability for the 30%-NQ content. Thus, among the three nitroguanidine propellants, the 30%-NQ propellant has a lower thermal stability.