Composite materials for hazard mitigation of reactive metal hydrides

In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. It is suggested that future work which strives to understand the interaction between the polymer and active material during synthesis as well as cycling may enable better engineering of the polymers to avoid destruction of it mitigating property upon use.

► We examined the hazard mitigation behavior of metal hydride–polymer composites. ► We successfully synthesized styrene- and siloxane-metal hydride composites. ► The composite material has a lower hydrogen capacity than neat metal hydride. ► The composites show promise, initially mitigating heat release upon oxidation. ► Cycling eliminates the mitigating behavior but a path forward is proposed.