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Lightweight and resistant, but apparently impossible to recycle. Now a team of scientists discovered how to recycle carbon fibres.
Planes, cars, bikes. When it comes to transportation, the material of the future – and of the most innovative present – is always the same: carbon fibres. Light and resistant, this material defeated the competition of aluminium, plastic and steel. Unlike these materials, though, carbon fibres have always been hard to recycle. Until now.
A group of researchers of the Georgia Institute of Technology developed a system to recover almost all the materials contained in some types of thermoset carbon fibre composites.
In the new process, the carbon fibre composites are soaked in an alcohol based solvent which slowly dissolves the epoxy that binds and gives shape to the carbon fibres. Once dissolved, the carbon fibres and the epoxy can be separated and used for new applications.
The most difficult part of the carbon fibre recycling process is the fibres’ polymer matrix, which is usually crosslinked, just like the rubber, and can’t be simply melted. It’s not easy to strip away the polymer to reclaim the embedded carbon fibres, which are more valuable to recycle.
The researchers focused on a specific type of carbon fibre using an epoxy resin called vitrimer, which gives shape to the compounds. Kay Yu, researcher at the Georgia Institute of Technology, explained: “Vitrimers contain dynamic bonds that can alternate their structure without losing network integrity under certain conditions. We let alcohol, which has small molecules, to participate in the network of alternating reactions, which effectively dissolved the vitrimer.”
The researchers believe that this new recycling process can have many industrial applications, with great benefits for the economy and for the environment. Moreover, the process is simple and straightforward enough to be applied on a wide scale to reduce the tons of carbon fibres that are discarded in the United States and Europe every year.