Plant-based epoxy enables recyclable carbon fibre!

 Plant-based epoxy enables recyclable carbon fibre!

"Thanks to recent advances in bio-based material design, recycling carbon fiber at an industrial scale could already be close at hand. Through a project supported by the US Department of Energy's Vehicle Technologies Office, under the Composites Core Program, Rorrer and other NREL researchers have shown that making carbon-fiber composites with bio-based epoxies and anhydride hardeners makes the material fully recyclable by introducing linkages that are more easily degraded. In fact, the recycling process — called methanolysis — can be selectively triggered at room temperature without degrading the quality or orientation of the fibers. That could represent a strong step toward a circular material, which can make carbon fiber cheaper and greener when used across multiple lives."

"The thermoset-nature of the cured epoxy makes those superior products difficult to break apart, especially without severely damaging the carbon filaments. Products made from carbon fiber — despite their premium price — often head to the landfill at the end of their lives, along with any efficiency benefits they may have earned."

Rorrer and teammates began experimenting with the chemistry of biomass to understand if it could enable a new epoxy designed for recyclability. Compared to the hydrocarbons in petroleum, biomass contains higher levels of oxygen and nitrogen, offering a different set of chemical possibilities.

"We essentially redesigned the epoxy amine resins — today's thermosets in carbon fiber — with epoxy and anhydrides synthesized from biomass, predominantly from the biological and chemical conversion of sugars," Rorrer explained. "We have shown that [the] reformulated resin can maintain and/or exceed all the same properties as in today's epoxy amine resins, but also make them recyclable by design, and at room temperature."

"Using a special catalyst, the NREL team was able to break down the bio-based resin at room temperature, a process known as "depolymerization." That allowed them to recover the carbon filaments while maintaining their quality and alignment."

"We can actually maintain the fiber quality over at least three material lives," Rorrer said. "So not only are we able to recycle it, we are able to recycle it without any detriment to properties. We are not downcycling the material at all."

Source:#managingcomposites