Recycled composites could be re-used in aircraft and cars

Researchers at Nottingham University are to collaborate with Boeing, which is now supplying its part-composite 787 airliner to clients.

Historically, composite materials such as carbon fibre-reinforced polymers, have proved to be difficult to recycle and so generally went to landfill.

Meanwhile, early attempts to make functional parts from recycled composites have shown them to have poor mechanical properties, such as reduced strength and stiffness.

‘Recycled fibres are not like virgin fibres, they’re not continuous and they don’t come in reels, so you can’t really get the high-fibre volume and high-fibre density for the highest-grade applications,’ project collaborator Dr Steve Pickering of Nottingham told The Engineer.

The team has been looking at ways of improving the properties of recycled composites, firstly at the recovery stage. For example, it has been investigating the use of supercritical fluids that can diffuse through solids like a gas and dissolve resin and separate the fibres of a composite.

With these cleaner fibres, the team is also looking at new manufacturing methods, for example, attempting to align the shorter fibres more closely to increase the density.

‘The question is identifying what the properties of the fibre are and finding appropriate uses for them,’ Pickering said.

‘Nobody is going to put recycled fibres back into an aircraft wing, but there are lots of other non-structural applications where you want to reduce weight.’

Boeing plans to invest $1m (£625,000) a year in the research collaboration with a view to commercialising some of the recycling technologies and perhaps finding a use for end-of-life composites from its new fleet of lightweight aircrafts.

‘There’s going to be more and more to recycle as time goes on, so hopefully we can complete the circle,’ Pickering said.