Carbon-fiber reinforced plastics (CFRPs) are used in a broad range of products, including automotive parts, construction materials and many others. Economically recycling these materials has proven challenging due to their multi-material makeup. Typically, they are chopped into pellets or strips that are not suitable for many end-use applications. Asahi Kasei Corp. (Tokyo; www.asahi-kasei.com) is scaling up a recycling technology that can recover continuous carbon fibers from CFRP using electrolyzed sulfuric acid to selectively decompose the resin matrix.
“This method allows the carbon fiber to retain its original strength and continuous nature while fully decomposing the resin that the carbon fiber is embedded in,” explains Yuji Okada, project leader of Asahi Kasei’s Recycled Carbon Fiber R&D Project.
Being able to selectively recover intact carbon fibers supports the circular use of recycled carbon fibers from automative parts back into new vehicles, for instance, since the recycled continuous carbon fiber can be handled in the same way as new carbon fiber and does not experience any detrimental “fluffing” or “twisting.”
Furthermore, the circularity potential of the technology could extend into the CO2-utilization realm, since the polymer matrix and adhesives surrounding the carbon fiber are decomposed into only CO2 and water. “Asahi Kasei possesses technology to produce chemicals using CO2 as a raw material. Therefore, we believe that in the future, the CO2 generated from the decomposition of the plastic matrix could potentially be effectively utilized as a raw material,” says Okada. He also notes that the electrolyte material used in the separation can be repeatedly electrolyzed for “theoretically infinite reuse.”
The company has successfully run the technology at the laboratory scale over a period of around two years, and construction is currently underway on a benchmark plant in Chiba Prefecture, Japan, with trial operations scheduled to begin before the end of 2025.
At the recent K Show in Germany, Asahi Kasei showcased some 200 meters of continuous carbon fiber created by using this recycling method.
Carbon-fiber recycling strategy
Source: Asahi Kasei