Theoretical Study of the Interfacial Force-Field, Thermodynamic Property, and Heat Stress for Plastic Bonded Explosives

The force-fields across the TATB/(paraffin, fluoropolymer), RDX/TATB, RDX/graphite and fluoropolymer/graphite interfaces are obtained by first-principles calculations and parameter optimization. Based on them, the composite materials are simulated in atomistic scale, and a set of thermodynamic properties are calculated, including the heat capacity, thermal expansion coefficient, Gruneisen coefficient, isothermal curve, Hugoniot curve, pressure field, and tension field. We find that the thermal expansion coefficient difference across the explosive/additive interface induces interfacial tension in warming process, the interfacial tension induces positive pressure on the explosive particle, and the positive pressure restrains the thermal expansion of the composite material. A physical picture to describe the influence mechanism of the interface effect on the composite property is obtained.