Using a mix of computer simulations and laboratory experiments, researchers from Penn State found that by adding small amounts of 2D graphene to the production process reduces the cost and increases the strength of the carbon fibres.
Cost analysis done for the project say that carbon fibre sells for around $15 per pound in the United States, and the team, which includes researchers from Penn State, the University of Virginia and Oak Ridge National Laboratory, in collaboration with industry partners Solvay and Oshkosh, wants to reduce that to $5 per pound by making changes to the complex production process. A lower production cost will increase carbon fibre’s potential applications. Further, the team’s research may lower the cost of producing other types of carbon fibres, some of which sell for up to $900 per pound today.
Currently, most carbon fibres are produced from a polymer known as polyacrylonitrile, or PAN, and it is pretty costly. The price of PAN makes up about 50% of the production cost of carbon fibres.
Małgorzata Kowalik, researcher in Penn State’s Department of Mechanical Engineering
PAN is used to create 90% of carbon fibres found in the market today, but its production requires an enormous amount of energy. First, PAN fibres have to be heated to 200-300 degrees Celsius to oxidize them. Next, they must be heated to 1,200-1,600 degrees Celsius to transform the atoms into carbon. Finally, they have to be heated to 2,100 degrees Celsius so that the molecules are aligned properly. Without this series of steps, the resulting material would lack its needed strength and stiffness.
The team reported in a recent issue of Science Advances that adding trace amounts of graphene to the first stages of this process allowed the team to create a carbon fibre that had 225% greater strength and 184% greater stiffness than the conventionally made PAN-based carbon fibres.
The flat structure of graphene helps to align PAN molecules consistently throughout the fibre, which is needed in the production process. Further, at high temperatures, graphene edges have a natural catalytic property so that the rest of PAN condenses around these edges.
With the new knowledge gained from this study, the team is exploring ways to further use graphene in this production process using cheaper precursors, with a goal of cutting out one or more of the production steps altogether, thereby reducing costs even more.