Molecular dynamics simulation of the interface interaction and mechanical properties of PYX and polymer binder

The interaction between four polymer binder molecules and 2,6-dipicrylamino-3,5-dinitropyridine (PYX) molecules was determined through the analysis of surface electrostatic potential and deformation electron density. The binding energy, mechanical properties, and cohesive energy density (CED) of Polymer Bonded Explosives (PBXs) based on PYX at different temperatures were studied. By comparing the binding energies of four polymer binders and three PYX crystal surfaces at five temperatures, it was found that the surface of PYX (011) was the most suitable surface, and the binding energy of EPDM (Ethylene Propylene Diene Monomer) and PYX (011) was the strongest by comparing the four polymer-binding molecules with the surface of PYX (011) at the same temperature. The CED values and distribution of CED for four PYX-based PBXs were analyzed with the change in temperature, and the conclusion was drawn that temperature had little influence on CED values. The descending order of CED values of four PYX-based PBXs at the same temperature was as follows: PYX/F2641 > PYX/F246G > PYX/F2311 > PYX/EPDM. At 298 K, the addition of polymer binders significantly changed the mechanical properties of PYX and reduced the stiffness and deformation resistance of the system. In addition, the C12–C44 value of the four systems was positive, which meant that the system was ductile. The order of toughness and ductility is as follows: PYX/F246G > PYX/F2311 > PYX/F2641 > PYX/EPDM. The addition of the polymer binder was helpful for the stability of the explosive. The theoretical detonation velocity and detonation pressure of the PBX systems were calculated.