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PLA Polyesters

She's showing off plastic containers made from corn.

AP Photo/Nati Harnik

Producing plastic from processed corn may seem like a pipe dream, but it's happening every day. Polylactic acid, or PLA, is another aliphatic polyester and one that can be made from lactic acid, which is produced via starch fermentation during corn wet milling. Although most often generated from corn, PLA can be made from wheat or sugarcane as well.

PLA boasts the rigidity to replace polystyrene and PET, but it has an edge over the real thing: It decomposes within 47 days in an industrial composting site, won't emit toxic fumes when burned and manufacturing them uses 20 to 50 percent less fossil fuels than petroleum-based plastic [source: Nakazawa]. Often, companies blend PLA with starch to reduce cost and increase its biodegradability.

Consumers may encounter PLA in bottles, bags and film, but it's only beginning to live up to its potential. In fact, if Walmart used 114 million PLA containers a year, company executives estimate they could save 800,000 barrels of oil annually [source: Royte]. If that isn't enough, scientists are trying to make PLA stronger and more heat-resistant. This should open up new applications for the popular green plastic, from automotive parts to coffee cups.

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