Theoretical investigations on stability, sensitivity, energetic performance, and mechanical properties of CL-20/TNAD cocrystal explosive by molecular dynamics method.

Abstract

The crystal models of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD), hexanitrohexaazaisowurtzitane (CL-20), and CL-20/TNAD cocrystal explosive with different component ratios were established. Molecular dynamics (MD) method was applied to predict the stability, sensitivity, energetic properties, and mechanical properties. The effect of component ratio on properties of CL-20/TNAD cocrystal explosive was investigated and estimated. Results show that the cocrystal model with component ratio in 1:1 exhibits the highest binding energy and it is more stable. In CL-20/TNAD cocrystal explosive, the interaction energy of trigger bond is increased by 0.8 ~ 15.0kJ/mol, implying that the mechanical sensitivity of CL-20/TNAD cocrystal explosive is lower than CL-20 and the safety is effectively improved. Compared with raw CL-20, the crystal density of cocrystal explosive is declined by 0.014 ~ 0.193g/cm3, detonation velocity is declined by 39 ~ 755m/s, and detonation pressure is declined by 0.95 ~ 11.40GPa; namely the energy density of CL-20/TNAD cocrystal explosive is lower than CL-20. The cocrystal explosives with component ratio in 10:1 ~ 1:1 still exhibit desirable detonation performance and can be regarded as high energy density explosives. The values of tensile modulus, shear modulus, and bulk modulus of CL-20/TNAD cocrystal explosive are decreased by 0.448 ~ 10.285GPa, 0.195 ~ 4.189GPa, and 0.194 ~ 6.292GPa, respectively, Cauchy pressure is increased by 0.990 ~ 5.704GPa, meaning that the rigidity, fracture strength, and hardness of cocrystal explosive are declined, while the plastic property and ductility are increased and the mechanical properties are improved. The cocrystal model with component ratio in 1:1 has the best mechanical properties. Consequently, the CL-20/TNAD cocrystal explosive with component ratio in 1:1 is more stable and insensitive; it also has high energy density and the best mechanical properties and may be an attractive candidate for high energy explosives.