NREL Publishes Methodology for Recycling All Elements in Carbon Fiber Composites

Final Up to date on: twenty fifth June 2025, 12:45 am

Know-how Helps Overcome Affordability Boundaries to Wider Use and Manufacturing of a Excessive-Worth Materials Present in Plane, Bicycles, Vehicles, and Extra

Deconstructing epoxy resins with scorching acetic acid has the potential to supply a scalable and inexpensive answer for recycling a fabric utilized in a spread of high-value client merchandise, in line with new analysis from the Bio-Optimized Applied sciences to maintain Thermoplastics out of Landfills and the Setting (BOTTLE) consortium.

Carbon fiber composites (CFCs) are high-strength, low-weight supplies produced from epoxy-amine resins that encase lengthy carbon fibers. CFCs allow lighter and extra environment friendly bicycles, planes, and vehicles and are a crucial part of the strain vessels used for compressed pure fuel transport and storage. Nonetheless, the associated fee and energy-intensive manufacturing of CFCs limits their software, and there’s a close to complete lack of scalable and economically viable recycling strategies for these vital supplies.

CFCs are typically made with epoxy-amine resins, comparable in chemistry to many epoxies generally present in {hardware} shops. These composites kind a stiff and resistant plastic, but in addition one that can not be dissolved or melted. Whereas the resins are comparatively low cost, the fibers they encompass usually are not, so the ensuing composites are fairly costly—many CFCs can value properly over $50 per pound.

“For an inexpensive analogy, think about a cake,” mentioned Stephen Dempsey, a postdoctoral researcher on the Nationwide Renewable Power Laboratory (NREL) and one of many first authors of the research. “As soon as the egg, flour, and sugar are within the batter and that cake is baked, it’s mainly not possible to get them again out. It’s comparable right here: The resin is chemically interlocked, and the bonds are fairly sturdy. Now we have to do one thing intense to get the fibers out, however we additionally should be cautious to not degrade the chemical substances within the resin past what’s essential, as that may waste on a regular basis, vitality, and uncooked supplies that went into making them within the first place.”

However even then, there is a little more complexity than in baking, as a result of these resins are sometimes manufactured from extremely complicated mixtures of molecules. A few of these compounds are widespread, and shared throughout many industries that use CFCs, however others usually are not. As well as, it’s at the moment difficult to establish precisely what the resin chemistry is earlier than recycling. A recycling methodology for CFCs should due to this fact be extraordinarily sturdy and able to dealing with numerous resin formulations.

The BOTTLE workforce’s answer ended up being surprisingly easy. Scorching acetic acid, the identical compound that’s present in vinegar, can cleave all the important thing bonds inside these resins. Former NREL postdoctoral researcher Ciaran Lahive (now at College of Manchester), and co-first creator on this research, demonstrated this response throughout an intensive response screening effort for one more mission.

The workforce realized one thing outstanding: Not solely do the polymer networks within the resin solubilize quickly, however the acetic acid additionally stabilizes their chemical parts, enabling excessive yields of reusable chemical constructing blocks. In depth optimization work from NREL interns Katie Stevenson (now at Columbia College) and Sydney Reiber (now on the College of Graz) led to a course of efficient on end-of-life waste from quite a lot of industries.

Importantly, the researchers additionally decided there was no affect on the energy of the recycled carbon fibers (rCF), which is crucial to making sure they maintain their worth after being extracted from the composite. To exhibit this, they took 80 grams of a scrap mountain-bike body manufactured from composite materials and deconstructed it. Utilizing the carbon fibers that they had simply extracted, they then made new composites that exhibited greater than twice the strength-to-weight ratio of metal.

Not solely is the price of rCF predicted to be fairly low in comparison with virgin fiber, with a worth of simply $1.50 per kilogram, however the vitality consumption can also be virtually zero when factoring within the recovered epoxy constructing blocks. The method isn’t restricted to CFC solely—glass fiber composites like these present in turbine blades, boat hulls, or car bumpers and hoods may be handled.

“Lengthy-term, this know-how may very well be used to create worth from difficult composite waste streams which might be at the moment piling up in landfills,” mentioned BOTTLE CEO Gregg Beckham, the senior creator of the research and a senior analysis fellow at NREL. “Present applied sciences usually are not but capable of make a dent in that waste stream, however we predict that this course of may very well be helpful for this software as properly.”

The invention holds the potential to energise the U.S. composite manufacturing business.

“If we will scale this course of and deploy it in the true world, we see no cause that complete panels on vehicles or trains couldn’t be manufactured from rCF composites as a substitute of metal or aluminum,” Dempsey mentioned.

The paper, “Acetolysis of epoxy-amine resins for carbon fiber-reinforced polymer recycling,” seems within the journal Nature. The opposite coauthors from NREL are William Michener, Hannah Alt, Kelsey Ramirez, Erik Rognerud, Clarissa Lincoln, Ryan Clarke, Nicholas Rorrer, and Katrina Knauer.

Funded by the U.S. Division of Power’s Superior Supplies and Manufacturing Applied sciences Workplace and Bioenergy Applied sciences Workplace, the work was carried out as a part of the BOTTLE consortium. Further funding was supplied as a part of a BOTTLE funding alternative announcement with the College of Delaware’s Middle for Composite Supplies.

Article from NREL.