Recyclable Composite Hydrogen Storage Tanks

Abstract Hydrogen fuel is becoming more popular as an alternative to fossil fuels, particularly for transportation. Hydrogen needs to be stored at high pressures in high-performance composite over-wrapped pressure vessels (COPV) to maintain efficiency. Currently, the only end-of-life option for these tanks is the landfill, which will become more detrimental as the demand for and thereby number of hydrogen tanks increases. By incorporating a vitrimer matrix to the carbon fiber overwrap, the tanks can be disassembled and unwound. This process allows for full recyclability as both the fiber reinforcements and the matrix can be reused. Filament winding was used to produce both tubular and flat specimens for mechanical testing and process characterization. The tensile strength of longitudinally reinforced vitrimer samples was significantly less than the traditional epoxy counterparts. This decrease was consistent with the trend of neat resin tensile strength differences between the two materials. However, the longitudinal strength properties were expected to be similar, as they are fiber dominated. Results indicated that the processing of the vitrimer led to volume fraction and void content variation. While the vitrimer technology is still under development, this work represents the first step towards fully recyclable COPVs and the ability for recover long tows of valuable carbon fibers.