CNN Sci-Tech: New plastics may keep soft drinks from falling flat

February 6, 1997
From Correspondent David George

RALEIGH, North Carolina (CNN) — Ever wonder why soft drinks sometimes go flat even before you’ve opened the bottle? Ever wonder when somebody’s going to do something about it?

Wonder no more. Researchers at North Carolina State University (NCSU) are experimenting with liquid crystal polymers they say could be used to make plastic soda bottles and other plastic packaging virtually impervious to gas leakage, thus greatly increasing the “shelf life” of hundreds of products.

Leakage is a universal problem in plastic packaging. Every plastic soda bottle that rolls off a production line, every food product packed in plastic, and every plastic container of any kind on any store shelf anywhere will leak to some degree.

It may not be apparent to the casual observer, but slow, invisible leaks can affect the quality of products.

“Anything we have is vulnerable to some degree to air, the oxygen in the air, loss of flavor, gain of outside odors,” said packaging consultant Aaron Brody.

The problem, NCSU researchers say, is that oxygen and other gasses dissolve into the walls of polymer-based plastic containers much like sugar dissolves in coffee.

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“The molecules of water actually dissolve into the body of the polymeric film, and then move through the polymeric film itself,” says Dr. Benny Freeman, one of the researchers trying to solve the problem.
Dr. Freeman speaking about this issue.

Freeman and others are conducting experiments to compare the ability of various liquid crystal polymers to form gas-tight barriers.

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The test involves suspending polymer samples from springs inside gas-filled chambers. The more gas a material absorbs, the heavier it gets, says doctoral candidate Chris McDowell.

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Freeman compares the molecules in polymers to logs lined up together to form an oxygen barrier 100 times better than that of today’s soda bottles.

Depending on the outcome of the experiments, the airtight polymers may have other uses. Freeman says the electrical industry is already considering using a sleeve made of liquid crystal polymers to extend the life of underground power cables.

And Brody, co-author of an authoritative book on packaging, says the day may soon come when the public will find even beer packaged in plastic, just like soft drinks.

“We’re converting just about everything else into plastic,” he says, “Why not beer?”

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