Local shock viscosity measurements at the interface of cyclotetramethylene-tetranitramine crystal and hydroxyl-terminated polybutadiene binder

In a heterogeneous microstructure such as plastic bonded explosives, the microscale shock behavior of different phases and the interface between the phases is crucial to correlate with the macroscale behavior of the material. The shock propagation between the different phases of material could be affected by delamination under shock pressure, temperature rise due to different dissipation mechanisms or chemical reactions. In this article, we investigated the shock propagation between hydroxyl-terminated polybutadiene (HTPB) binder and cyclotetramethylene-tetranitramine (HMX) crystal under shock loading by characterizing local shock viscosity at the interface. The shock was created at strain rates higher than 10⁶/s by the impact of the planar disk of aluminum foil accelerated by laser-based setup. The local measurements at the interface were done using time-resolved Raman spectroscopy by combining a streak camera to obtain 1ns time resolution. The change in the Raman shift in the time domain was analyzed to extract information about local stress and shock stress rise time at the interface. The results show different rise times at the interface compared to a bulk HTPB binder and HMX crystal providing insight into the time-dependent local behavior and dissipation mechanisms.