Computational Simulation Study On Structure And Performance Of Polymer Bonded Explosives

With the appearance of energetic composite material on the basis of polymer bonded explosives (PBX), energetic materials (for example, mixed explosive, propellant, propelling agent and booster etc.) are endowed with many good general performances, such as high energy density, good mechanical property and high safety performance etc. So, they have been widely applied in modern national defence, national economy and correlative fields. It is of both theoretical and practical significance to explore the structure and performance of energetic composite materials and to offer the information, rules and guidance for designing PBX formulations. In this work, molecular dynamics (MD) together with quantum mechanics (QM) method have been employed to simulate and calculate a series of PBX. Many valuable new results are found.First, MD simulations have been done on TATB-based PCTFE PBX with 'adsorbing coat' model. The results show that when the polymer is added to base explosive, its elastic coefficients and modulus are reduced, which suggests the elastic properties of PBX are increased and its mechanical properties are improved. The intermolecular interaction between TATB and PCTFE, mainly H-bond and vdw interaction, is quite strong. To a certain extent, with the increase of polymer PCTFE concentration in PBX, the binding energy increases, the rigidity decreases, and the elastic property increases. With the increase of temperature, the rigidity of PBX decreases, the elastic property increases and binding energy decreases. By MD simulations and theoretical calculations of four different TATB-based fluorine-polymer (PVDF, F₂₃₁₁, F₂₃₁₄ and PCTFE) PBXs, the following conclusions can be drawn. Fluorine-polymer binder can improve the mechanical property of base explosive but weaken its detonation heat and velocity. The order of detonation heat of four PBXs is TATB/PVDF>TATB/F₂₃₁₁>TATB/F₂₃₁₄TATB/PCTFE, while the order of detonation velocity is in reverse. This rule can provide guidance to the design of PBX formulations.Second, MD simulation and 'adsorbing coat' model can be applied for four constituents of PBXs. By MD simulations on two practical HMX-based PBXs JOB-9003: (HMX/TATB/F₂₃₁₁/paraffine) and JO-9159 (HMX/NC/F₂₃₁₁/paraffine), the structure, binding energies and mechanical properties are obtained. Detonation heat and velocity and sensitivity of four constituents HMX-based composite material have been calculated. By means of pair correlation function and DTF-B3LPY calculations, the interactions between constituents and base explosive in PBX is analyzed. The results show that there...