From A Single Grain to Microstructure: An Experimental View of How Explosive Grains Interact Under Shock Compression

Experimental observations of hot spot initiation and propagation in explosives have proven a challenging goal. We have developed an experiment where a small piece of polymer bonded explosive is shocked with a laser-launched flyer plate and probe the response with nanosecond video and time-resolved emission spectroscopy. This shows us the spatial dependence and temperature of thermal emission, providing insight on how microstructure affects shock initiation. Due to the high throughput of the tabletop shock compression experiments, large quantities of many different materials can be tested. In this study, we will discuss HMX in a polymer binder. By precisely controlling the particle size distribution as well as the particle loading in binder, we begin to understand in detail how the hot spots on individual particles react and spread to the bulk material. We observe a transition between isolated explosive particles, being either single or polycrystalline, up to a limit of HMX-loading where it can be viewed as a traditional plastic-bonded explosive. This method provides greater detail about how microstructure of plastic-bonded explosives changes the performance.