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Using Carbon Fiber to Cut Production Costs and Strengthen Materials for Automotives

June 01, 2020 by Luke James

Carbon fiber, which is five times stronger than steel, is the ideal material for making things that need to be hardwearing and lightweight at the same time.

However, the problem with carbon fiber is that it is very expensive to produce. This makes it unsuitable for use as a material in applications where it would otherwise be very useful, such as automobiles.

That was, until now; a team of scientists from Pennsylvania State University (Penn State), in collaboration with colleagues from the University of Virginia and Oak Ridge National Laboratory, have reportedly developed a new way to create carbon fiber that is not only cheaper but makes the material stronger, too.

Slashing Production Costs

If created in the right way, long strands of carbon-based atoms that are narrower than a human hair can exhibit superior stiffness and strength, in contrast to traditional construction materials like steel, while also being very lightweight. For these reasons, carbon fiber has been widely used in aeroplanes for decades where its use is more cost-effective than in consumer automobiles.

"Even though carbon fibers have really nice features, they would make a car far more expensive" with the way carbon fibers are manufactured now, said Adri van Duin, professor of mechanical and chemical engineering, Penn State. "If you can get these properties easier to manufacture then you can make cars significantly lighter, lower the cost of them and make them safer."

Today, carbon fiber costs around $15 per pound but this can go all the way up to$900 per pound depending on the type. The research team, in collaboration with industry partners Solvay and Oshkosh, wants to slash this to \$5 per pound by tinkering with the complex production process. This would make it more cost-effective for use in many applications including consumer automobiles.

The New Method

Currently, carbon fiber is produced using polyacrylonitrile (PAN), a polymer. This polymer, which is used to create around 90% of carbon fibers found on the market today, is very costly and makes up around 50% of the production cost of carbon fibers.

This is because the production process requires multiple rounds of heating to temperatures as high as 2,100 degrees Celsius in stages. This oxidises the PAN fibers, turns the atoms into carbon, and aligns the molecules in the correct way. Without this level of heating, the resulting carbon fiber material would lack its characteristic strength.

The Penn State team found that adding graphene to the carbon fiber production process improves the material’s strength. Image credit: Penn State

By adding trace amounts of graphene to the first stage of the production process, however, the team was able to create a carbon fiber that had 225% greater strength and 184% greater stiffness. This is because the flat structure of graphene helps to align PAN molecules consistently throughout the fiber. And at the high temperatures, graphene’s edges have a natural catalytic property so that the rest of the PAN condenses around it.

With the knowledge the team has gained from the study, they are exploring ways to use graphene in the production process with the goal of cutting out one or more of the production steps to reduce costs further.