Flakes Key to Flexible Fiber
Carbon fiber with graphene oxide flakes

A research team at Rice has found that using graphene oxide as the raw material in carbon fiber enhances its mechanical and electrical properties.

Project: Carbon fiber with graphene oxide flakes
School: Rice University
Location: Houston
Principal Investigator: Changsheng Xiang

In 2008, researchers at the Smalley Institute for Nanoscale Science and Technology at Rice University began work on a new recipe for creating carbon fiber. The goal was to develop a raw material to make carbon fiber that combines the advantages of the two primary carbon fiber precursors currently on the market – polyacrylonitrile (PAN) and mesophase pitch. The research team includes students under the tutelage of two professors: Matteo Pasquali, whose primary appointment is in chemical and biomolecular engineering, and James M. Tour, whose main appointment is in the chemistry department.

“The ideal precursor for high-performance carbon fibers should first be able to form a liquid crystal phase to produce fibers with good intrinsic alignment – a key to high performance,” says Changsheng “Charles” Xiang, a graduate student in chemistry. “In addition, the size of the precursor is important.” Because carbon fiber fractures at flake boundaries and interfaces, larger disks or longer rods would reduce the number of boundaries and therefore improve mechanical properties.

Using the raw materials PAN and mesophase pitch has limitations. While PAN-based carbon fibers have high tensile strength, they have lower stiffness due to poor alignment. Conversely, mesophase pitch-based carbon fibers offer high stiffness, but lower tensile strength because of the small flake size of individual molecules. The researchers at Rice discovered graphene oxide satisfies both requirements. “We can make the next-generation carbon fibers from graphene oxide with both high tensile strength and high stiffness,” says Xiang.

That’s good news for manufacturers in the aerospace and automotive industries, though the project is in the early stages. Still, Xiang expects a graphene oxide-based carbon fiber could become a reality within five years if a materials supplier performs enough optimization research.