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Scientists perfecting planet-friendly plastics

Possible uses for the biodegradable plastic include shotgun shell cases, plastic cutlery and dog bones. Researchers (left to right) Kim Stelson, Vaughan Voller, and Mrinal Bhattacharya display some of their products   
February 1, 1999
Web posted at: 2:45 PM EST

By Environmental News Network staff

(ENN) -- When the snow melts on European ski slopes, many are littered with plastic lift tickets. But that could change if plastic manufacturers start making the tickets from the totally biodegradable plastic developed by Mrinal Bhattacharya and his colleagues.

Bhattacharya, a professor of biosystems and agricultural engineering at the University of Minnesota, uses protein found in cereal grains, along with plant starch and a degradable synthetic polymer, to make the plastic. Visit his lab and he'll show you golf tees, forks, spoons and doggie chew bones made from the material.

Kim Stelson, a professor in the Department of Mechanical Engineering, works with Bhattacharya and Civil Engineering Associate Professor Vaughan Voller to head the project. He describes starched-based plastic as a reacted blend of starch and synthetic polymer. Starch is a renewable agricultural product and the use of this plastic will reduce the world's dependence of oil -- a non-renewable resource.

"Starch-based plastics are recyclable and biodegradable, thus reducing the environmental impact," Stelson says. "They also can be made cheaper than other plastics."

The starch used to create the biodegradable plastic -- typically wheat gluten -- costs about 15 cents a pound. The cheapest commercial plastics cost about $1 a pound. Thus, when this starch-based plastic becomes available to manufacturers, it could be the cheapest biodegradable plastic. Now, most environment-friendly plastics cost about $2.50 a pound. In the first stages of the project, University researchers have brought the cost of their plastic down to about $1.50 a pound.

So what's keeping it off the market?

"It's still three times as expensive as regular plastic," says Bhattacharya. "We have to break into a very competitive market."

However the researchers pointed out that although the plastic is highly biodegradable, it will not break down in the same way and in the same amount of time in every environment. For example, microorganisms will devour the natural fibers of the plastic quickly in a warm and moist compost pile and slowly in a dry, hot desert.

The scientists found that in ideal environments warmer than 40 degrees Fahrenheit, the polymers could breakdown in as little as 15 days. However, in the winter with exposure of less than 20 degrees Fahrenheit, the plastic disintegrates in a much longer amount of time.

"Although (it's been) a two-year process, it is far from perfect," says Jacob John, a research associate in the Department of Biosystems and Agricultural Engineering who has worked on different aspects of starch-based plastics for more than two years. "The problem now lies in the process to create products made from this plastic."

Possible uses for the plastic include shotgun shell cases, plastic cutlery and dog bones. These products are particularly attractive for mass-production because the market for the biodegradable form of these products is so large.

For example, although it is illegal for a hunter to drop a shotgun shell in a pristine wilderness area, it does happen. But if the shell is made of this decomposing plastic, it could disappear by the next hunting season. Forks, spoons and knives made out of this material are also very marketable to seafaring organizations or businesses.

Bhattacharya also says there may be hope for getting a toehold in Europe, where fees for nondegradable garbage disposal are steep. Bhattacharya is also working with the Navy, which is interested in biodegradable cutlery for ships, where space is at a premium.

For more information, contact Mrinal Bhattacharya, (612)625-5234.

Copyright 1999, Environmental News Network, All Rights Reserved

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