Modified Mechanical Strength, Thermal Decomposition, and Combustion Characteristics of Nitroguanidine Propellant with Graphene Nanosheets as Reinforcement

High energy, high strength, and stable combustion character are the basic requirements of a modern gun propellant (GP). Herein, graphene nanosheets (GNSs) are introduced into the nitroguanidine gun propellant (NQ-GP) as reinforcements to modify its comprehensive performance. A series of in-depth characterizations were conducted to characterize the structure and composition of the propellant, demonstrating that GNSs integrated well in the propellant system. The result of mechanical properties manifested that the anti-impact strength increased with the increase in the content of GNSs in the propellant, and GNSs with a low content of 0.5% in the GP exerted better mechanical strength than those with a high content under different temperature conditions; the brickwork bridging effect enhancement mechanism was proposed as well. Besides, the thermal decomposition character was investigated under different heating conditions like programmed and high pressure. It revealed that GNSs with a high content can produce a catalytic effect on the thermal decomposition process of the propellant like the heat release. Additionally, the analysis of the thermal decomposition kinetics of the propellant by the method of Friedman demonstrated that the addition of GNSs with a proper content could further enhance the activation energy of NQ-GP with thermal stability, which is opposite to the result of linear fitting methods of Kissinger and Ozawa. The results obtained by the different methods were likely to vary with the action mechanisms of the different systems or thermal decomposition stages. It also demonstrated that different high-pressure conditions and GNS contents can produce obvious influence on the thermal decomposition behavior of the propellant, such as T-p and heat release. Moreover, it was found that the introduction of GNSs would not influence the burning stability of the propellant and that the burning rate coefficient (a) and the burning pressure exponent (n) could also be modified with the proper content of GNSs. Hence, the work presented herein highly broadens the application scope of the reinforcement nanofiller and will be of potential value to the community development in high-energy and high-strength GPs.