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The Search for Biodegradable Plastics
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# : |
17193 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
12 / 1990 |
3,008 Words |
| Author
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Gail Finlayson Dutton
Gail Finlayson Dutton is a free-lance writer specializing in
science and technology. Her work has appeared in Science,
Applied Radiology, Occupational Health & Safety, and other
publications. Dutton is based in Westminster, California. |
The search for strong durable plastics began early in this century and, by World War II, when they first came into widespread use, it seemed plastics would be with us forever. In a sense, those plastics will be. A plastic pop bottle discarded today will be around for between 200 and 400 years.
The problem is that our overflowing landfills cannot continue to absorb the 10 million tons of plastic trash created in the United States alone each year. In terms of volume, that's about 20 percent of all U.S. trash.
Cities are beginning to call for bans on nondegradable plastic and a return to paper packaging is mentioned occasionally. The solution, however, is not to return entirely to paper packaging. Worldwide, that would add 55 billion pounds of trash per year, according to chemist James E. Guillet of the University of Toronto, and would call for devoting an extra 162 million acres of forest - six states the size of Tennessee - to paper production and increasing annual worldwide energy consumption by 228 percent.
There are no simple solutions to reducing waste. "The issue of materials for packaging is very complex," Guillet said at the American Chemical Society meeting last August. The best solution, according to many scientists, is a combination of solutions that include biodegradable plastics, plastic recycling, and composting.
Biodegradation defined
The term biodegradable plastics means many things, even within the scientific community and the plastic industry. By January 1991, the American Society for Testing and Materials expects to have a standard, industry-accepted definition of the term. Currently, biodegradable is used to describe both biodisintegratable plastics that disintegrate into polymer chains, and biodegradable plastics that break down in to water and carbon dioxide.
Why plastics don't degrade well
"There's a lot of controversy about degradation, especially in landfills," said Ramani Narayan, professor of chemical engineering at Michigan State University in East Lansing, and senior scientist at the Michigan Biotechnology Institute. "Landfills are passive environments and most things shouldn't be in landfills." After all, if paper doesn't degrade well in landfills, why should
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