The United States rubber industry, especially for car tires, has depended on petroleum to make its product since World War II, when supply of the rubber tree prevalently grown in Asia was no longer available to America. Researchers with the University of Minnesota’s Center for Sustainable Polymers are now working to again transform the industry by returning to a natural source for rubber – Corn.
Associate Professor Paul Dauenhauer and his team set out to use starches derived from a source like corn, as well as grass and trees, because they are almost identical to the size of isoprene, which is the key molecule found in tires.
Through a hybrid process, Dauenhauer says they were able to transform the sugar molecule from corn into isoprene, making the final product identical to the petroleum-produced outcome. This result could be a big boost for Minnesota corn growers looking to further expand uses for their commodity.
“Rubber is a big industry. Car tires are one that everyone knows, but it is everywhere,” he says. “It is a big volume problem to go after, which makes it a good fit for agriculture with its large volume and it being ubiquitous.”
With rubber no longer dependent on a fossil fuel for production, Dauenhauer says sustainability is a big benefit as the industry switches over. The process to create isoprene from petroleum was not very selective, meaning it required a lot of the fossil fuel for a small yield of isoprene, obviously an environmental concern. Isoprene derived from natural sugars like those from corn were created to be very selective, Dauenhauer says.
In addition, carbon sequestration, which is the process by which carbon is removed from the atmosphere, is taking place with this new process. Carbon captured in corn ends up in tires, as an example.
“Every time you make a product like a tire from corn, you are taking CO2 out of the air,” he says. “This means you are essentially doing carbon sequestration as a consumer product.”
Although the Center for Sustainable Polymers is not yet working with tire manufacturers, Dauenhauer says many in the tire industry have been trying to produce renewable isoprene for some time. Tire manufacturers now would be able to take the renewable isoprene and eventually create a tire identical to what is on the road today.
“It is an identical molecule, so it will be an identical product,” Dauenhauer says.
This project received funding from the Minnesota Corn Research & Promotion Council (MCR&PC). Working closely with the Minnesota Corn Growers Association, MCR&PC administers the efficient and effective investment of Minnesota’s corn check-off. Dauenhauer and his team also received significant funding from the National Science Foundation.