A molecular dynamics study of interface interactions and mechanical properties of HMX-based PBXs with PEG and HTPB

Molecular dynamics simulation was applied to investigate the interface interactions and mechanical properties of beta-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)-based polymer-bonded explosives (PBXs). The interface structures of HMX (100) crystal surface with the following two polymers individually: poly (ethylene glycol) (PEG) and hydro-terminated polybutadiene (HTPB), were analyzed using pair correlation function (PCF), and the interfacial binding energies between them were calculated. It is shown that there exist hydrogen bonds and electrostatic interactions on the interface. By calculating and comparing the bond lengths and distributions for possible initial bonds fractured in detonation, it is known that the interactions do not affect the stability of the PBXs. Moreover, the elastic constants for HMX and the HMX-based PBXs were computed using static elastic constants analysis method, and the engineering moduli and Poisson ratios were derived by Reuss average. Based on the elastic properties related to the plastic ones, it is indicated that the ductibility of crystalline HMX can be effectively improved by blending these polymers in a small amount. (C) 2007 Elsevier B.V. All rights reserved.