Carbon fiber is one of the hottest products in manufacturing and fabrication. To hear some tell it, carbon fiber is an all-in-one miracle material that can replace everything from steel to aluminum to concrete. The composites industry talks up carbon fiber to such a degree that it's easy to believe there's nothing negative about the space-age composite. Yet carbon fiber does pose a significant problem we are now just beginning to talk about: a lack of recycling.
Carbon fiber recycling has eluded the composites industry for decades. The problem is rooted in the fact that carbon fiber materials cannot simply be melted down and repurposed like aluminum and steel. They cannot be put in a chemical bath like paper. They cannot be ground down and reconstituted into a new product in the same way scrap timber can be used to make low-density fiberboard (LDF).
Rock West Composites, a Utah company that specializes in composite materials, explains that the thing that holds carbon fibers together is an epoxy resin that binds to the fibers to create an extra strong polymer. Once that resin cures, it is nearly impossible to break the bonds through any simple means. Thus, recycling carbon fiber in a way that results in a usable material is not easy.
Current Recycling Processes
For the record, recycling carbon fiber is by no means impossible. There are a limited number of companies already doing it. But the only viable processing method developed thus far is one that burns away the resin to free up the carbon fibers embedded within. This is a workable solution, albeit not an ideal one.
New carbon fiber consists of long, perfectly aligned strands of carbon that can be spun into threads to create all sorts of materials ranging from tubes to sheets. In fact, the strength of carbon fiber as a composite material rests in these long, perfectly aligned strands. Burning off resin results in shorter strands that are not as precisely aligned. Thus, recycled carbon fiber is significantly weaker.
This isn't necessarily a problem inasmuch as recycled carbon fiber can be used to make things like tennis rackets, where maximum strength isn't required. But recycled carbon fiber cannot be used for things like car bodies, airplane fuselage panels, and boat hulls.
The other problem with recycled carbon fiber is that it is not necessarily any better than other cheap materials with similar tensile strengths. That means there is no incentive for companies to choose recycled carbon fiber over other options.
A Solution in the Works
It has been suggested that the recycling problem inherent to carbon fiber is one of the things preventing greater penetration of the automotive market. We do know that carbon fiber is too costly for auto makers to use on a grand scale, and it is believed that a lack of cost-effective recycling is one factor keeping prices high. Improving our recycling efforts in order to produce a material that is as strong as new carbon fiber would bring prices down dramatically.
Fortunately, the solution appears to be in the works. According to a March 2017 article published by The Guardian, researchers in England may have come up with a process for realigning recycled fibers to create longer, tighter fibers that are strong enough for automotive manufacturing. Let's hope they can make it work.
Carbon fiber is definitely a worthwhile material for manufacturing and fabricating. The recycling problem seems to be its only weakness at this point. Solve that problem and we pave the way to using carbon fiber and other composites in new and innovative ways.