Quantitatively elucidate the reinforcement mechanism of bonding agents in azide propellant system via molecular dynamics simulation

Bonding agents contain certain functional groups, connecting oxidizer and binder together by forming electrostatic interaction and covalent bonds, respectively, which is vital for enhancing the mechanical properties of propellants. Yet, efficiently regulate the ratio of bonding agents to approach optimal enhancement is still challenging, due to the absence of specific and quantitative reinforcement mechanism. In this study, the mechanical properties regarding the azide propellant system with ε-CL-20 (ε-hexanitrohexaazaisowurtzitane) and different ratios of neutral polymeric bonding agents (NPBAs) are studied by all-atom molecular dynamics simulation. In contrast to fully cross-linked as anticipated, 60% cured network is much better at improving interface strength. Also, the number hydrogen bond at the interface is a vital determinant of binding energy, with approximate seven hydrogen bonds achieving interface strength of 370.39 kcal/mol. Simulations on mechanical properties indicates that 30% cured network exhibited optimal mechanical characteristics. The outcome emphasizes how crucial the conformation created by the binder and bonding agents is. In the meantime, the addition of these enhancement mechanisms will significantly aid to better design of bonding agents and performance improvement of propellant.