Biodegradable plastics made from corn

Researchers at Iowa State University have found a way to reinforce biorenewable plastics made of corn or soy proteins. They are using high-powered ultrasonics to reinforce the plastics with nanoclays. Even if the results are encouraging, these biodegradable plastics should not become available before a few years.

Biodegradable plastics have already been created by using proteins from plants such as corn or soy. But they were not strong enough to be used by the industry. Now, researchers at Iowa State University have found a way to reinforce these biorenewable plastics. They are using high-powered ultrasonics to reinforce the plastics with nanoclays. Even if the results are encouraging, these biodegradable plastics should not become available before a few years. But read more...

These plastics have been developed by David Grewell, an assistant professor of agricultural and biosystems engineering, and his research team working on polymer processing. But how biodegradable plastics can be made with corn proteins? Grewell keeps a plastic model of a molecule looking like a ball.

That's about the shape of a soy or corn protein [...] Then he unfolded the model into a long, straight loop. That's what happens when researchers add some glycerin -- a byproduct of biodiesel production – and some water to the molecule. And that's how biorenewable, biodegradable plastics can be made from the proteins in Iowa crops.

As these plastics are not terribly strong, he worked with other researchers, including Michael Kessler, an Iowa State assistant professor of materials science and engineering, and his research group to reinforce the plastics with nanoclays.

But what exactly are nanoclays? Here is the answer from Nanocor, a supplier of nanoclays specifically designed for plastic nanocomposites. Nanoclays are clays from the smectite family which have a unique morphology: they form platelets about 1 nanometer thick and 100 nanometers in diameter. Below is an example of the structure of one nanoclay raw material named montmorillonite. (Credit: Nanoclay Structures, Nanocor)

Nanoclay structure

Apparently, it's difficult to use these nanoclays. So the researchers turned to "high-powered ultrasonics -- high-frequency sound waves too high for human hearing – to separate and disperse the platelets." Below is a picture of Grewell showing the plastics developed by the reserachers' teams (Credit: Iowa State University)

Plastics made from corn proteins

Grewell is using ultrasonics for a while now. If you're interested by this work, you should read another Iowa State University news release, "Ultrasonics boosts release rates of corn sugars for ethanol production" (June 1, 2006) or a presentation about Bio-Renewable and Bio-Degradable Plastics (PDF format, 11 pages, 181 KB).

Sources: Iowa State University news release, October 30, 2006; and various websites

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