Molecular Dynamics Simulation Study On The Properties Of Composite Energetic Materials And The Thermal Decomposition Mechanism Of HMX And HMX-based PBX

Both HMX (octahedron-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) and RDX (1,3,5-trinitro-1,3,5-triazacyclohexane) are single compound explosives with excellent explosive performance, which are widely applied to military and civilian field.In this thesis, there were two parts:1. With COMPASS force field, the relationships between structure and performance of three-components (RDX/IPN/AP) and five-components (RDX/IPN/AP/Al/paraffin (or mineral wax)) were studied by the classical molecular dynamics (MD) simulation.2. The trigger and reaction mechanisms ofβ-HMX and PBX (β-HMX/paraffin, β-HMX/PEG) were researched under high temperature, and we also compared the influence of the trigger mechanism for different polymers.As for the multiple components, firstly, the properties of mechanics performance, cohesive energy density(CED), length of the trigger-bonds and lattice parameters for three-components (RDX/IPN/AP) were studied and calculated under five temperatures(195,245,295,335 and 365K),which were valuable to analyzing the relationship of sensitivity and temperature effects. So, we could evaluate their safety performance. Then, we added Al and paraffin (or mineral wax) as high-energy additive and binder to calculating the same performances. In addition, we also compared the different performance for the five components containing paraffin or mineral wax. All of these researches above enriched the design of PBX formula, which might be available for finding and researching PBX.Concerning to HMX and its PBX models, firstly, we made β-HMX (2x2x2) [100] system decompose under canonical ensemble (NVT, T=1800K) to analyse the trigger-bonds and reaction mechanism with the help of CP2K package and SCC-DFTB theory. Then, we composited HMX with paraffin or PEG polymer binders to reveal the impact of trigger bonds and reaction procedures. In a word, it’s the first time to take QMMD methods to investigate decomposition of HMX and HMX-based composite materials, and the first time to reveal why these polymers could retard the trigger and reaction of most high energetic explosives. All the work will lay a foundation for researching and understanding the passivation mechanism of polymers absolutely..