Molecular dynamics simulation of CL-20 based high temperature resistant PBX

Context

To address the issue that the output charge in existing Deflagration to Detonation Transition (DDT) detonators cannot withstand high temperatures of 200 °C, and to improve the output performance of the detonator, a CL-20 (Hexanitrohexaazaisowurtzitane) based polymer bonded explosive (PBX) was investigated as the primary charge material for the detonator. To select the most suitable binder for thermal resistance, molecular dynamics (MD) simulations were employed to evaluate the performance of different binders at various crystal planes and temperatures. The results indicate that among the five PBXs models, CL-20/F₂₆₀₂ exhibits the highest binding energy and the shortest bond initiation length at both ambient and elevated temperatures. CL-20/F₂₆₁₁ demonstrates stronger hydrogen bonding interactions and superior thermal stability at high temperatures. CL-20/PCTFE shows the best ductility, while CL-20/F₂₆₀₂ possesses the second-best ductility. Therefore, PBXs containing F₂₆₀₂ possess the best stability, compatibility, and satisfactory ductility, while PBXs with F₂₆₁₁ exhibit the best thermal stability. Both F₂₆₀₂ and F₂₆₁₁ are suitable as binders for CL-20.

Methods

Molecular dynamics (MD) simulations were carried out using the Materials Studio software to calculate the binding energies, trigger bond lengths, and mechanical properties of five PBX models at different crystal planes at 298 K, and at various temperatures on the (0 1 1) crystal plane after a 1 ns NPT dynamics simulation. The total MD simulation time was 1 ns, with a time step of 1 fs, and the COMPASS force field was employed throughout the simulation.