New sugar-based plastics can be tossed in home compost bin

By Sandy Bauers, February 18, 2010

London researchers have  come up with a new sugar-based polymer that they say could make food packaging and other disposable plastic items suitable for being composted at home along with the usual veggie peelings and other organic waste.

This would be huge.  Right now, most “compostable” plastics have to be sent to industrial-size facilities. And they’re often made from food crops such as corn, sugar beets and potatoes, creating ethical concerns in a world where many poor people go hungry and using food stocks for plastics might drive up prices.

The degradable polymer is made from sugars known as “lignocellulosic biomass,” which come from fast-growing trees and grasses, or renewable biomass from agricultural or food waste, according to a press release from Imperial College London, where the team of engineering and physical sciences researchers are based.

Lead researcher Charlotte Williams says significant research is going into developing greener plastics — not only for environmental reasons, but also because of economic and supply considerations. Around 7% of worldwide oil and gas resources are consumed in plastics manufacture, with worldwide production exceeding 150 million tons per year. Almost 99% of plastics are formed from fossil fuels, according to the press release.

For the plastic to be useful it had to be manufactured in large volumes and by produced in a low-energy, low-water process, Williams says. In contrast, the leading biorenewable plastic, polylactide, is formed in a high energy process requiring large volumes of water. In addition, when it reaches the end of its life polylactide must be degraded in a high-temperature industrial facility.

The new polymer’s oxygen-rich sugars allow it to absorb water and degrade to harmless products – meaning it can be tossed on the home compost heap and used to feed the garden.

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