USC researchers have developed a study that promises complete upcycling of high-performance composite materials, according to Travis Williams, a professor of chemistry at Dornsife College Of Letters, Arts and Sciences and the leader of the study.

Carbon fibers are expensive, high-performance materials largely used in the construction of aircrafts and automobiles. The substance that keeps airplanes together is made up of eight layers of woven carbon fiber held together with a strong type of epoxy resin. Williams said as an aircraft reaches the end of its life, it will turn into waste because there is currently no technology to separate the carbon fibers from the epoxy.

“Trying to un-thermoset a thermoset, un-epoxy an epoxy, is like trying to unboil an egg,” Williams said. “We started inventing reactions to do that for the different kinds of epoxies and different kinds of thermosets that they use in aviation. It worked in a number of cases … you can get it back, still woven as fabric, and nobody else has been able to do that. So this got people’s attention.”

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Williams said 99.1% of the composite materials end up in landfills due to the “expensive” process of recycling. He said 1% of the composite that is recycled is subjected to high heat, which damages the fibers, such as polymer. The study has pioneered a method that transforms polymer, one of the cheapest fibers in the composite space, into high-cost, valuable substances, Williams said.

“Nobody had ever asked that about taking aircraft epoxy apart, so we were the first to report if you do it oxidatively, these are the molecular events that happen,” Williams said. “Now, all sorts of people are making all sorts of creative contributions to this [because] we taught them how to think about it like molecules, not like the material … A lot of molecular people are coming up with great ideas to handle all sorts of composites. It’s really cool to watch.”

Williams said in the study, researchers have focused on breaking down the mechanism behind different chemical reactions. Despite initially being published in lesser-known journals, according to Williams, the study has quickly gained the attention of many.

“I would argue that our method is superior to other methods out there in the literature today,” said Justin Lim, a doctoral student studying chemistry. “Our group is advantageous because we aim to make our methods sustainable.”

Ding-Yuan Lim, a graduate student studying chemistry, said another factor that sets USC’s approach apart is their effort to incorporate common chemical reagents, which helps in cost reduction, ensures safety and makes large-scale application feasible, while most of the studies out there focus on using supercritical conditions like high pressure and high temperatures.

The researcher’s process of upcycling carbon fibers from composite material consumes 10.8 to 36 megajoules of energy per kilogram, while the production of new carbon fibers consumes 198 to 594 megajoules per kilogram, said Madison Fette, a graduate student studying chemistry. Fette said the cost of upcycling the carbon fibers is also only a fifth of producing original fibers.

Williams said the carbon fibers upcycled through this method are lighter, stronger and stiffer than aluminum. As a result, they benefit the aviation industry tremendously. Due to their light weight, aircrafts made from recycled carbon fibers require 20% less fuel which also leads to a significant reduction in CO2 emissions, Williams said.

Lim said the study also ensures that carbon fibers recycled through their process would maintain nearly the same mechanical properties as original fibers and are at least within 90% or higher of carbon fibers’ original strength, which has been tested by USC researchers through single fiber tensile tests.

“The thing that’s going to break us are the people who buy these materials philosophically believe that the recycled fiber is inferior,” Williams said. “What’s going to kill us is … the manufacturing community who seem to believe that recycled [fiber] is lower quality.”

Williams said he believes the situation might change as President Donald Trump’s administration shifts national priorities in energy.

“Policy wise, whilst there’s a lot that you can say that’s not real flattering about our current president, I think he might help us as we try to change manufacturing through energy transition, through the transition from traditional metals to composite and modern materials,” Williams said.