Performance characterization of surface-coated ultrafine hexanitrostilbene-IV by experiment and simulation

Hexanitrostilbene (HNS) is an explosive characterized by low mechanical sensitivity, high thermal stability, and excellent physicochemical and radiation resistance. It is widely used in both military and civilian applications. HNS-IV, known for its appropriate impact sensitivity to narrow pulse detonation, is currently the primary filling in shock wave detonators. However, due to the large specific surface area and high surface activity of ultrafine HNS-IV, it exhibits significant static electricity and poor flowability, which adversely affect the accuracy of its mass loading and subsequently density. To address the issues of poor flowability and moldability between ultrafine HNS-IV particles, this study utilized molecular dynamics simulations to select a high-performance, heat-resistant binder. Using this binder and graphite as an antistatic agent, a modified sample of ultrafine HNS-IV was prepared via the solvent evaporation method. The modified and unmodified samples were then subjected to comprehensive tests for morphology and composition, differential scanning calorimetry (DSC), repose angle, bulk density, explosion point, and charge amount.

Using molecular dynamics (MD) methods within the Materials Studio software, we computed the binding energies, initiation bond lengths, and mechanical properties of four types of polymer-bonded explosives (PBX) following a 1 ns NPT dynamic simulation. The MD simulation was conducted over a total duration of 1 ns with a time step of 1 fs. The simulations utilized the COMPASS force field, and the temperature was maintained at 298 K.