13. Interface Mechanical Properties in Energetic Materials Using Nanoscale Impact Experiment and Nanomechanical Raman Spectroscopy

Energetic materials are sensitive to mechanical shock and defects caused by a high-velocity impact may result in unwanted detonation due to hot-spot formation. In order to understand the underlying mechanism, characterization of high strain-rate mechanical properties needs to be studied. One of the key factors that can contribute to this type of defect is the failure initiated at the interfaces such as those between Hydroxyl-terminated polybutadiene (HTPB) and Cyclo-tetra-methylene-tetra-nitramine (HMX) (or HTPB and Ammonium Perchlorate (AP)). In this work, interface mechanical properties of HTPB-HMX and HTPB-AP interfaces are characterized using nanoscale dynamic impact experiments at strain rates up to 100 s⁻¹. The binding agent was added to the mixture in order to analyze the effect of chemical composition on the interfacial mechanical properties. For HTPB-AP sample, Tepanol is used as the binding agent and for HTPB-HMX sample, Dantocol was used as the binding agent. The impact response is determined in the bulk HTPB, HMX, and AP as well as at the HTPB-HMX and HTPB-AP interfaces. A strain-rate-dependent viscoplastic power law-based constitutive model was obtained by fitting the experimental stress–strain–strain-rate data. The effect of binding agent on interface level failure properties was studied using an in situ nanomechanical Raman spectroscopy (NMRS) setup.