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Future of corn-based plastics showcased at EXPO

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Written by Jonathan Eisenthal

Advances in chemistry and chemical engineering continue to offer paths for replacing petroleum with corn as a feedstock for plastics. By using a renewable source (corn) instead its oil-based counterpart, the research could reduce the environmental impact of plastic, both in the making and its disposal.

At 2019 MN Ag EXPO in Mankato, researchers with the University of Minnesota Center for Sustainable Polymers showed off the intriguing results of scientific work supported by the Minnesota Corn Growers Association and the Minnesota Corn Research & Promotion Council.

Among the new avenues of investigation: methods to make the corn-based bioplastic PLA even more useful by making it a more pliable plastic. Literally billions of bushels of corn consumption could result from a new approach to the conversion of lactic acid into acrylic acid through an ingenious method of dehydration. The project would introduce corn into a number of everyday products.

“The process of fermenting corn to make lactic acid and then dehydrating it into acrylic acid can deliver a very useful material,” Yutong Pang, a graduate student working on the Acrylic Acid research, noted. “Acrylic acid is used to make such items as paints, diapers and glues. We’re estimating $23 billion dollars in worldwide demand. It’s a big market.”

The research is well on the way to solving a thorny problem that creates inefficiency in the conversion of lactic to acrylic acid. The project employs chemicals called amines to block an unwanted side reaction. The process can thus deliver a 90-percent efficiency of lactic-to-acrylic acid conversion, making it very commercially viable.

Charles McCutcheon, a graduate student working on the PLA research, presented a project producing a blend of corn-based PLA plastics with better stretching capabilities.

“With the addition of a very small amount—about five percent—of another plastic, we can increase the ability to stretch the PLA as much as 45 times more. This is essential when you want to use a plastic for grocery bags, which have to be pliable, not brittle,” said McCutcheon.

The Minnesota Corn Research and Promotion Council is entering into its fourth year of support for the Center for Sustainable Polymers. MCGA Senior Research Director Paul Meints said the research has exciting potential for corn utilization and the environment.

“Producing the foundation molecules of plastics from sustainable sources means they are both green in the production of the material, and after use, these materials are compostable,” Meints said. “They are not going to sit in a landfill for 10,000 years. They are going to have a quick breakdown in composting, or they break down naturally, via a period of exposure to sunlight. That’s good for the environment, and that part of adding value to the corn grower is exciting to us.”

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