Graphene-Reinforced Carbon Fiber Is Much Stronger And Stiffer

Written by intelligentliving.co on August 5, 2021. Posted in Current News

Carbon fiber is a super-strong yet lightweight material. It is five times stronger than steel, twice as stiff and around 1.5 times lighter. It’s the ideal material for making things that should be lighter but still need to be strong, such as cars, airplanes, and sports equipment. It would be used a whole lot more too if it wasn’t so expensive to make.

Now, a group of scientists from Pennsylvania State University (in collaboration with the University of Virginia, Oak Ridge National Laboratory, and industry partners Solvay and Oshkosh) came up with a new way of creating the material that not only makes the process cheaper but also strengthens the fibers. And the magic ingredient is the beloved 2D sheet of carbon atoms – graphene. The team is optimistic that their discovery could lead to carbon fiber being used more in the manufacture of cars, improving their safety, and reducing their cost.

Adri van Duin, a Penn State professor of mechanical and chemical engineering and director of the MRI’s Materials Computation Center, said:

Even though carbon fibers have really nice features, they would make a car far more expensive with the way carbon fibers are manufactured now. 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.

Image: Margaret Kowalik and Adri Van Duin / Penn State

Carbon fibers have been the backbone of airplane production for decades. But when they branch out to other applications such as bikes and cars, they produce only top-end products, too expensive for most to afford. The current market price for carbon fiber is around US$15 per pound (0.45 kg). The team’s breakthrough may one day reduce that figure to US$5.

Małgorzata Kowalik, a researcher in Penn State’s Department of Mechanical Engineering, said:

Currently most carbon fibers 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 fibers.

Making PAN requires massive amounts of energy because of the extreme temperatures necessary to convert the polymer into long, strong strands of carbon-based atoms. The 3-step process involves heating PAN fibers at increasing temperatures from 200-300 degrees Celsius in the first phase to 2,100 degrees Celsius in the third. Step one oxidizes the strands, step two transforms the atoms into carbon, and step three aligns the molecules properly. 90 percent of carbon fibers available are made using PAN.

Using a mix of laboratory experiments and computer simulations, the researchers added graphene to carbon fiber and analyzed its properties. The team wanted to find out if they could modify the process to be less reliant on PAN. So, they tested what would happen if they substituted some graphene in its place. They found that by adding trace amounts of the material (only 0.075 percent concentration by weight) to the first stage of the process, it enhanced the final product considerably. Their graphene infused carbon fiber had 225% greater strength and 184% greater stiffness than conventionally made PAN-based carbon fibers.

Their analysis revealed that it was because the flat structure of graphene helps to align PAN molecules consistently throughout the strands. Also, when graphene is exposed to high temperatures, its edges adopt a natural catalytic property causing PAN to condense around these edges.

Van Duin said:

We connected experiments of different scales to not only show that this process works, but it gave us an atomistic-scale reason why these types of additives work. That knowledge allows us to optimize the process further.

The following video is a computer simulation of adding graphene to the first phase of the process of growing carbon fibers:

The impressive boost in performance has motivated the researchers to further explore the potential of graphene (along with cheaper precursors) in the production process to hopefully remove some of the steps altogether – thereby reducing the costs even more.

Meanwhile, there are several other exciting ways graphene is being used, such as to make safer hair dyes, to coat facemasks and make them repel viruses, to clean the air, and to strengthen recycled rubber material for durable flooring.

See more here: intelligentliving.co

Header image: Margaret Kowalik and Adri Van Duin / Penn State

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