Resisting the Pressure: Epoxy Resins for Filament Winding

One of the most discussed technologies for climate protection and energy generation is hydrogen and the fuel cell. The focus is on questions such as production and transport. If produced with renewable energy, for instance with the power of a wind blade, the resulting “green hydrogen” would have either none or only a minor carbon footprint. One of the problems, however, is regarding transportation: Very high pressure or extremely low temperatures are necessary to store as much gas as possible in a reasonable space. This has not been efficiently possible with the previous metal containers.

Therefore, more and more Composites based on Epoxy Resins and carbon fibers are the typical reinforcements used for compressed gas storage. Composite-based tanks offer even more benefits compared to metal: they are corrosion and fatigue resistant (including resistance to a wide range of chemicals), have a good adhesion to metals and fibers, offer enhanced service lifetimes (up to 30 years versus 15 years), are up to four times lighter than usually used metals and have an improved energy storage density as well as extended containment pressures (e. g. 5000 psi and higher with a practical structure weight). Not to forget that the reduction of weight by using composites allows for significant reduction of emissions. Another advantage: Composites can be produced in unique sizes and shapes.

Typically, this composite pressure vessels are produced with the filament winding, one of the methods of Composites Processing, just like Pultrusion, Prepreg, Resin Infusion, or Hand Layup. Filament winding is a fabrication technique often used for manufacturing closed end structures, such as pressure vessels or tanks. This process involves winding filaments under tension over a rotating mandrel.

The filaments are soaked in a bath with resin as they are wound onto the mandrel. But the product range for composites fabricated with filament winding is much wider. This technique is applied in the production of pipes, aircraft fuselages, lamp posts, yacht masts, golf clubs, oars, bicycle forks and rims, or power and transmission poles – to only name a few.

To make this possible, there are a few requirements to the Epoxy Resins used in the process. They need an appropriate viscosity-temperature profile for fiber wetting, offer adequate stability and reactivity and thermal stability and mechanical performance after cure.

The producers of Epoxy Resins invest in research and determined testing of materials to further develop those technologies, further improving the toughness and damage tolerance of cured Epoxy Thermoset – optimising it for the societal needs of our time.