Researchers at Georgia Tech, the United States, have developed a method to recycle nearly 100 percent of the materials in certain types of thermoset carbon fiber composites. During the new process, the carbon fiber composites are soaked in alcohol, which slowly dissolves the epoxy that binds and gives shape to the carbon fibers. Once dissolved, the researchers can separate the carbon fibers and the epoxy and use them for new applications.
“This method we think could have a lot of immediate industrial applications, with lots of economical and environment benefits,” said Kai Yu, at Georgia Tech. “Traditional carbon fiber has historically presented a number of challenges for recycling. The polymer matrix is usually crosslinked, just like the rubber, and it can’t be simply melted; it’s very hard to strip away the polymer to reclaim the embedded carbon fibers, which are more valuable to recycle,” said Jerry Qi, at Georgia Tech.
The research team focused on carbon fiber that uses a special type of epoxy called “vitrimer epoxy” to give the composite component its shape. “Vitrimers contain dynamic bonds that can alternate their structure without losing network integrity under certain conditions. We let alcohol, which has small molecules, to participate in the network of alternating reactions, which effectively dissolved the vitrimer,” Yu said. The new recycling process has the potential to reduce the thousands of tons of carbon fiber waste generated each year in the US and Europe.