In-situ X-ray tomography during mechanical loading to observe microstructural damage

To develop increasingly resilient polymer-bonded explosive formulations, understanding and controlling particle-binder interaction and adhesion behavior is key. Material damage can be induced by many thermal and mechanical insults, and tends to initiate and concentrate at existing defects and interfaces between particles and binder. This work is targeted at characterizing the microscale behavior of the particle-binder interphase, or the extended interaction region, and its role in the mitigation of thermomechanical damage in the bulk composite explosive system. Specifically, we present on small scale quasi-static tension experiments of samples consisting of controlled particles and binders. Samples of hydroxyl-terminated polybutadiene (HTPB) and polydimethylsiloxane (PDMS) are loaded with surrogate explosives, or other particles of interest, and then loaded in tension inside of an x-ray microcomputed tomography (XCT) instrument. This process allows for detailed radiographs and full 3D XCT datasets of the deformation and damage induced inside the microstructure. Data generated by these experiments is further analyzed to characterize the effective particle-binder adhesion quality via measurement of void volume as a function of tensile load. This process will enable direct comparisons of various adhesion modification techniques (e.g. surface coatings, particle treatments, etc.) to mitigate damage at the interface during thermomechanical loading.