Molecular simulation was applied to investigate the mechanical properties of β-octahydro- 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and the polymer-bonded explosives (PBXs) which were made from the HMX as a base and F₂₃₁₁ as a binder, in NVT ensemble using COM-PASS force field. The PBXs’ model was constituted by putting F₂₃₁₁ on crystal (001), (010) and (100) surface respectively. At 295 K, the elastic constants and the effective moduli were calculated by statistic analysis mode. Cauchy pressure C₁₂-C₄₄ was also calculated. It was shown that the rigidity was weakened and the ductibility was improved by adding small amount of F₂₃₁₁, and the ductibility improvement was most obvious when F₂₃₁₁ was put on HMX (100) crystal surface. From the temperature 245 to 445 K with the increase step of 50 K, pure HMX crystals and HMX (100)\F₂₃₁₁ PBX were allowed to dynamically evolve. It is indi-cated that the mechanical properties of pure HMX crystals are unchanged because thermal effect of the volume is constrained by NVT ensemble. However, the ductibility of HMX (100)\F₂₃₁₁ PBX changes according to a parabola with increasing temperature due to the improvement of F₂₃₁₁ chain moving ability and the simultaneous increment of high energy conformation ratio in this molecular chain, i.e., the increment of the molecular chain rigidity.

Key words: octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, polymer-bonded explosive, molecular dynamics, mechanical property