Molecular Dynamics Simulations for Effects of Fluoropolymer Binder Content in CL-20/TNT Based Polymer-Bonded Explosives

In order to better understand the role of binder content, molecular dynamics (MD) simulations were performed to study the interfacial interactions, sensitivity and mechanical properties of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-trinitrotoluene (CL-20/TNT) based polymer-bonded explosives (PBXs) with fluorine rubber F(2311). The binding energy between CL-20/TNT co-crystal (1 0 0) surface and F(2311), pair correlation function, the maximum bond length of the N–NO(2) trigger bond, and the mechanical properties of the PBXs were reported. From the calculated binding energy, it was found that binding energy increases with increasing F(2311) content. Additionally, according to the results of pair correlation function, it turns out that H–O hydrogen bonds and H–F hydrogen bonds exist between F(2311) molecules and the molecules in CL-20/TNT. The length of trigger bond in CL-20/TNT were adopted as theoretical criterion of sensitivity. The maximum bond length of the N–NO(2) trigger bond decreased very significantly when the F(2311) content increased from 0 to 9.2%. This indicated increasing F(2311) content can reduce sensitivity and improve thermal stability. However, the maximum bond length of the N–NO(2) trigger bond remained essentially unchanged when the F(2311) content was further increased. Additionally, the calculated mechanical data indicated that with the increase in F(2311) content, the rigidity of CL-20/TNT based PBXs was decrease, the toughness was improved.