Carbon fibers are stronger and lighter than steel, and composite materials based on carbon fiber reinforced polymers are being used in a growing number of applications, including major sections of the new Boeing 787 aircraft. But scientists believe carbon fiber technology could produce even stronger composites.
Georgia Tech researchers have developed a new technique for producing carbon fibers that sets a new milestone for strength and modulus — a measure of stiness. Their success stemmed from a new approach to spinning polyacrylonitrile, an organic polymer resin used to make carbon fibers.
“By using a gel-spinning technique to process polyacrylonitrile copolymer into carbon fibers, we have developed next-generation carbon fibers that exhibit a combination of strength and modulus not seen previously with the conventional solution-spun method,” said Satish Kumar, a professor in the Georgia Tech School of Materials Science and Engineering, who leads the project. “In addition, our work shows that the gel-spinning approach provides a pathway for even greater improvements.”
The gel-spun carbon fiber produced by Kumar’s team was tested at 5.5 to 5.8 gigapascals (GPa) — a measure of ultimate tensile strength — and had a tensile modulus in the 354 to 375 GPa range. The material was produced on a continuous carbonization line. The research is part of a project sponsored by the Defense Advanced Research Projects Agency (DARPA) and was reported in the journal Carbon. —RICK ROBINSON