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Breakthrough may help PLA take the heat from hot-filled apps

By Rory Harrington , 02-Sep-2010
Last updated the 06-Sep-2010 at 13:00 GMT

US researchers are claiming a breakthrough that could boost the heat resistance of bioplastic polylactic acid (PLA) sufficiently, allowing it to be used in hundreds of new packaging applications.

The team from the US Government’s Agricultural Research Service (ARS) and private company Lapol said they have created a modifying system that could see PLA used in hot-filled applications across the food and beverage industry.

Heat tolerance

Corn-based plastics are made by fermenting corn sugar to produce lactic acid. This substance is then used to form PLA. The fact that the bioplastic has a lower heat tolerance than some petroleum-based plastics excludes it from being used for some applications, explained the group consisting of ARS chemist William J. Orts, along with Allison Flynn and Lennard F. Torres from the Santa-Barbara-based plastics company.

To raise the temperature at which PLA may distort - known as its ‘heat deflection temperature’ – the scientists have developed a temperature deflection modifying mechanism that significantly boosts its heat resistance properties. The modifier is said to be more than 90 per cent corn based and fully biodegradable.

Preliminary tests indicate that, when blended with PLA, the modifier can raise the bioplastic’s heat-deflection temperature by at least 50˚F, said the group.

“With further research and development, the heat modifier might make it possible for hundreds of products that currently can’t typically be made with PLA to one day be manufactured with this bioplastic,” added the researchers.

Hot-filled

Thanks to the modifier, corn-based PLA could be used for food and beverage containers that are hot-filled – loaded at the processors while the product is still hot from pasteurisation. Today’s PLA typically can’t take the heat of hot-filling, said the team.

ARS and Lapol said they are currently seeking a patent for the invention.

“Right now, there are no commercially available heat-deflection temperature modifiers for PLA,” says Lapol chief operating officer Randall A. Smith. “It’s an emerging market.”