U working on a better plastic made from corn

Angela Gray

Corn moves from the cob to the job for some University researchers.

Professor Shri Ramaswamy and other University researchers are working to improve the properties and performance of the bio-based polymers used in corn-based products.

One of the products derived from corn includes plastic.

Corn-based plastic is biodegradable and made with polylactic acid, which is one of the bio-based polymers introduced in the marketplace.

Ramaswamy and his colleague professor Rich Cairncross from Drexel University, received a grant to study one of the problems associated with the type of plastic made from corn-derived polylactic acid.

He said the project is an investigation into how polylactic acid products react with water.

“I’m working on the use of this plastic in water bottles,” Ramaswamy said.

Being bio-based, polylactic acid interacts with moisture and transmits water easily. This is one of the reasons polylactic acid degrades rapidly, Cairncross said.

Ramaswamy said the transportation of moisture through polylactic acid can pose problems in long-term storage and use of water bottles.

“The problem we are working on is to better understand how water moves through polylactic acid,” Ramaswamy said.

Cairncross said that if you have a polylactic acid water bottle at room temperature it is stable and won’t degrade, however, if you warm it to 140 degrees Fahrenheit, it degrades rapidly and the polylactic acid would turn “to dirt in two months.”

Under standard landfill conditions, these corn-derived plastics essentially degrade within 30 days – the plastics go completely back to water and lactic acid and leave no solid waste.

Cairncross said corn-based plastics have environmental benefits because of a reduction in fossil fuels used to make polymers for petroleum-based plastics and a decrease in polymers entering compost.

“Using these products can reduce pollution problems at landfills and reliance on petroleum as a feedstock (to make plastics),” Cairncross said.

He said polylactic acid is well-suited for disposable dishware and food packaging containers that don’t hold liquid.

During testing, Ramaswamy said, they mix polymers with water and put them in an oven and after a few days take them out and weigh them.

“You can physically see the weight decrease,” he said.

He said researchers also chemically analyze the composition, which kind of molecules dissolve and physical properties.

Mary Rosenthal, global communications spokeswoman for NatureWorks, a company that makes corn-based plastics, said it is important for consumers to use plastics made from corn, if only to save petroleum.

“As far as other energy uses, instead of putting oil into petroleum-based plastic,” she said, “we use corn because it is renewable.”

Rosenthal said the market for corn-based plastics is growing.

She said that from 2004 to 2005, the company grew more than 200 percent and is on track for a triple-digit growth rate in 2006.

“There is a growing demand seen with companies, including Wal-Mart,” she said.

Wal-Mart has gone with four of the NatureWorks packages for its strawberries, brussels sprouts, herbs and fresh cut fruit, Rosenthal said.

“Those four packages have transferred into more than 100 million corn-based plastic packages in Wal-Mart stores across the nation.”

She said people can find the NatureWorks plastics locally in Kowalski’s Markets as well.

Ramaswamy said people will not buy something just because it is environmentally friendly.

“The corn-based products need to be economically friendly and it takes time to make further developments and improvements.”

He said companies in Europe already commonly use the corn-based products and the United States slowly is starting to introduce the products into their own markets.