Study on Mechanical Improvement of CL‐20 Energetic Co‐Crystals Based PBX by Surface Modification

Abstract

Low melting point compound MTNP was usually adopt to form co-crystal explosive with CL-20 to reduce sensitivity, and the co-crystal may have the potential of green engineering application. Improving mechanical properties of co-crystals explosive is one of the effective ways to broaden its practical application. In this work, CL-20/MTNP energetic co-crystal was selected to be coated by polydopamine (PDA) and neutral bonding agent (NBA), with enhanced mechanical properties and developed interfacial strength between crystal and binder. The TG-DSC curve showed that thermal decomposition of co-crystal ex-plosives divided into two steps, and the melting point delayed to 210 °C compared with that of MTNP. After surface modification, the storage modulus of PBX was increased by more than 20 % at the temperature range of (25-120) °C, and creep strain was also effectively reduced. The Brazilian and compressive strength of PDA coating samples increased by 69.89 % and 210.53 % respectively, as well as improved elongation, leading to increased fracture toughness.Here, the highlighted modification on the surface of CL-20/ MTNP co-crystal can be used as a reference insight to improve the mechanical properties of new explosives.

Temperature-dependent decomposition of the CL-20/MTNP cocrystal after phase separation

“…8 Compared with pure MTNP, the endothermic peak for the melting process of CL-20/MTNP cocrystal was shifted towards a higher temperature, which could be attributed to the strong intermolecular interactions as indicated in earlier references. 11,35 Moreover, the initial decomposition temperature of the CL-20/MTNP cocrystal was significantly lower than those of individual CL-20 and MTNP samples. Interestingly, with the exception of the endothermic peak in the melting process, the two-step partially overlapping exothermic peak patterns of the CL-20/MTNP cocrystal and 1 : 1 molar ratio of CL-20 and MTNP mixture were comparable.…”