01 October 2002
Warning colors breaking out
Kingston, R.I. - There will soon come a day when a fire door changes color when hot, football jerseys can tell when a player is overheating, road signs change color to indicate icy road conditions, and food packaging stamps disappear when products have been kept at room temperature for too long.
University of Rhode Island chemists Brett Lucht and Bill Euler and chemical engineer Otto Gregory are developing heat-sensitive polymers that change color at various temperatures. So far they have successfully created a polymer that changes from red to yellow at 180°F (the temperature at which a person would suffer a burn) and at other warm temperatures.
Work started when a company approached Gregory with an idea to coat cookware with a material that would change color when hot. He created a polymer, but it decomposed upon repeated exposure to high oven temperatures.
Since then, the trio has succeeded in placing this polymer in plastics, where it remains embedded. This discovery is important to the food storage industry because it is the only Food and Drug Administration-approved pigment that changes color.
"This polymer has an important safety application," said Lucht. "It has the potential to prevent people from burning themselves and eating spoiled foods."
He calls this "smart packaging" because the packages would tell consumers the temperature of the product. For example, coffee lids could change color at extreme temperatures, and milk cartons could have a mark that disappears if the carton reaches room temperature.
The polymers could work in a variety of products, including plastics, paints, inks, and rubbers. They can work with vinyl seating to warn of hot seats; train wheels or brakes to show when they are beginning to wear out; radiator caps and engine hoses to warn of extremely high temperatures; and road signs to warn drivers of potentially hazardous conditions.
"The potential uses for these polymers are endless. These products could forewarn people that they are in potentially dangerous situations," Gregory said.
Lucht and Euler are now concentrating on creating color changes for low temperatures and creating polymers that make more than one color change-ideally, red for hot and blue for cold. They are also studying other vivid colors.
Gregory is focusing his research on uniformly dispersing polymers throughout different materials.
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