Tech Briefs

Composite could be cost-effective for manufacturing.

A team of researchers led by the University of Colorado has determined that carbon-fiber composites, which are stronger than steel and lighter than aluminum, can be easily and cost-effectively recycled into new material that, they say, is just as robust as the original ones.

Fig. 1 – Diagram of recycling/reuse program.

In addition, fabricating the new material and its recycling are energy-efficient and comparatively fast, potentially addressing barriers to wider use in manufacturing.

The team’s findings, published in the journal, Advanced Materials, address the fact that, while composite materials, like those containing embedded carbon fibers, are often used where high-strength, light-weight ratios and rigidity are required, they are generally not recyclable. The glue that binds the fiber in most carbon-fiber composites can be broken down with expensive, energy-intensive processes that may yield toxic waste.

Carbon-fiber composites can also be crushed into a fine powder, but composites made with short fibers are weak. Therefore, millions of pounds of carbon-fiber composites can end up in landfills.

Wei Zhang, Associate Professor of Chemistry and Biochemistry, leading the team, says: “We can achieve complete recyclability” of both the glue and the carbon fiber. (See Figure 1)

Zhang, working with former doctoral student Philip Taynton, say that they have also discovered a way to make hard but malleable plastics that can be refashioned into new equally strong plastic using just heat or water. Recycling the team’s carbon-fiber composites simply requires soaking the composite in an organic solution at room temperature.

Zhang and Taynton co-founded a start-up called Mallinda, LLC, which is a mash-up of “malleable industries.” They note that the team’s carbon-fiber composite, for which the university’s Technology Transfer Office has filed a US patent application, is more quickly fabricated than most carbon-fiber composites, which can take an hour to cure. The university’s composites can be formed in 60 seconds. The university and Mallinda have signed an exclusive licensing agreement.

For more information, visit www.colorado.edu/news.