A resurgent interest in more sustainable and environmentally friendly carbon fibers has led researchers in the U.K. to convert cellulose fibers into high-strength carbon fibers, according to a report at MaterialsToday.com.
Steve Eichhorn and his colleagues at the Universities of Exeter and Manchester are developing strong, lightweight carbon fibers made from recycled plant matter that could replace glass fibers in high-performance composites used in cars and airplanes. Additionally, manufacturing the new composites avoids the creation of toxic gases, such as hydrogen cyanide, as byproducts that are the result of the current polyacrylonitrile (PAN) process.
Eichhorn’s team started their process with Cordenka™, a commercially available regenerated cellulose fiber produced by the German developer of the same name. The fibers were first pre-treated in a furnace heated to 200°C to stabilize the structure. Further heat treatment and graphitization at 2000°C produces carbon fibers that look like multi-walled carbon nanotubes with ordered graphitic-like crystallites, the report says. High-resolution transmission electron microscopy reveals a microstructure of carbon layers arranged in a cylindrical shape, which the researchers believe arises from graphitization of the cellulose’s fibrous structure.
The carbon fibers have very good mechanical properties, Eichhorn told Materials Today. Not only did the researchers graphitize cellulose fibers, for the first time they also graphitized fabrics woven from Cordenka. Lightweight woven carbon fiber sheets are particularly attractive to auto manufacturers as they can be formed into panels and infused with resin to form aesthetically pleasing and hard-wearing composites.
Cellulose fibers are not only more sustainable and environmentally friendly, but could save time and cost in composite production, Eichhorn says. He is now looking at how to improve the mechanical properties of the fibers further and weave more complex structures. Ultimately, Eichhorn and his team plan to create some cellulose-based test composites for the automotive industry.