Published on August 27th, 2017 | by Steve Hanley0
Plant Waste Could Make Less Expensive, More Sustainable Carbon Fiber Possible
August 27th, 2017 by Steve Hanley
Carbon fiber is a miracle substance. Lighter than aluminum, stronger than steel, impervious to water, it could be used to manufacture stronger, lighter automobiles like the BMW i3 and i8. It would be used in airplanes, trucks, and other vehicles if it wasn’t so expensive, and it is hardly a sustainable material. Most carbon fiber today is made from polyarylonitrile, otherwise known as PAN, which is a pricey, non-renewable polymer.
Researchers at Washington State University think they may have found a way to make carbon fiber that is less expensive and more environmentally friendly using lignin, a substance found in the cell walls of plants and trees. After they are used to make paper or ethanol, the lignin is left behind and often gets burned or discarded in landfills.
“Lignin is a complex aromatic molecule that is mainly burned to make steam in a bio-refinery plant, a relatively inefficient process that doesn’t create a lot of value,” says professor Birgitte Ahring, the principal investigator on the project. “Finding better ways to use leftover lignin is really the driver here. We want to use bio-refinery waste to create value. We want to use a low value product to create a high value product, which will make bio-refineries sustainable.”
That high value product is carbon fiber infused with lignin to make it less expensive and more environmentally friendly. “Our idea is to reduce the cost for making carbon fiber by using renewable materials, like biorefinery lignin,” says professor Jinxue Jiang, one of the researchers at the University of Washington. Carbon fiber made entirely from lignin is too weak for most uses, but blending PAN and lignin may be the perfect solution. They presented the results of their research at the annual meeting of the American Chemical Society this week.
Professor Ahring’s team tried various proportions of lignin and PAN using a process called melt spinning. “You elevate the temperature of the polymer blend until it melts, so it can flow,” Jiang says. “Then, you spin these polymer melts until the fiber forms.” Ultimately, they found that a blend of about 30% lignin resulted in carbon fiber strong enough for various automobile and aircraft parts
The next step is to take the results of the laboratory research and apply it to real-world manufacturing. “If we can manage to get a fiber that can be used in the automobile industry, we will be in a good position to make biorefineries more economically viable, so they can sell what they usually would discard or burn,” Ahring says. “And the products would be more sustainable and less expensive.”
Source: American Chemical Society