Softmat collaborates with Expleo on a new carbon fibers recycling method

Carbon fiber is an integral part of many leading industries (aerospace, automotive, wind power). This structural material is renowned for its mechanical performance and unrivalled lightness. But most of its production involves the use of synthetic products derived from petroleum, and the processing consumes enormous amounts of energy. In partnership with CIRIMAT, the SMODD team has worked with Expleo to develop a low environmental impact process for recycling carbon fiber and epoxy resin composites used in the primary structure of aircraft. Ecological and energy-efficient, this new method is protected by two patents.

Together with Nicolas Mistou (who defended his thesis in July 2023), the researcher Emile Perez was responsible for developing the chemical process and recovering the fibers, while his CIRIMAT partners were in charge of the physical and mechanical characterisation of the recycled fibers and their reintegration into new composites using bio-sourced epoxy resins.

Emile explains:

“There are many techniques for recycling composite materials, but they all have major flaws. They are not very environmentally friendly, very energy-intensive and require special installations.
With our process, given that the fibers are only slightly damaged, we can envisage reusing them after several recycles.”

Indeed, this new chemical recycling method recovers untangled carbon fibers with structural properties up to 90% of those of the original material, as well as recovering the depolymerised epoxy resin, all in a single reaction.

The system is based on an oxidising system operating in the form of baths, made up of propylene carbonate as a solvent, hydrogen peroxide as a reagent and a very common catalyst: citric acid. Unlike competing methods, none of the chemical elements used are toxic, and the ingredients have the added advantage of being available at low cost, making the prospect of industrialisation all the more viable.
Carried out in less than 24 hours at ambient pressure and 60°C, this reaction requires very little energy compared with the methods currently used to recycle carbon fiber composites. This environmentally-friendly process also enables the solvent and catalyst to be recycled, maximising efficiency while minimising chemical waste.

Major stakeholders in the aeronautics sector have expressed their enthusiasm for this research project, which was selected as part of the call for expressions of circular economy interest 2023 “Commercial aircraft at end of life” launched by Aerospace Valley, Airbus and Tarmac Aerosave. It also won the Airbus Composite Recycling Award for the same year.

In addition to its impact on major economic and technological sectors for the future, this innovation project also opens up other research prospects:

“AAfter this initial success, we can look forward to developing similar processes for other materials that are currently difficult to recycle or have too great an impact on the environment.” concludes Emile.

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