Crystallographic Origins of Temperature-Dependent Strain Rate Sensitivity and Deformation Mechanism Transitions at TATB/F2314 Interfaces: A Molecular Dynamics Study

Interfaces play a critical role in the mechanical integrity of polymer-bonded explosives (PBXs) based on 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), yet how crystallographic orientation governs their temperature- and strain-rate-dependent mechanical response remains poorly understood. Here, molecular dynamics simulations were performed on interfaces between TATB and the fluoropolymer F2314, with TATB exposing the (001), (010), and (100) facets, over wide ranges of temperature and strain rate. Crystallographic orientation was found to regulate the mechanical response by determining deformation mechanisms. The edge-exposed (010) and (100) facets allowed basal-plane slip to develop within the available loading time, producing weakly temperature-dependent apparent strain rate sensitivities. In contrast, the planar (001) facet constrained basal deformation at low temperatures but underwent coupled structural rearrangement at 400 K, enabling kink band formation and increasing its rate sensitivity. Rapid loading kinetically suppressed these coordinated mechanisms and shifted deformation toward distributed molecular deformation. F2314 simultaneously accommodated heterogeneous deformation through rate- and temperature-dependent chain motion, coupling polymer relaxation to the orientation-dependent response of TATB. The competition between these processes further governed damage modes. As such, these findings establish a relationship between crystallographic geometry and interfacial deformation kinetics, providing an atomistic basis for multiscale modeling and microstructural design of TATB-based PBXs.