September 2, 2016
Engineers create plastic clothing that cools the skin
When it comes to shopping for back-to-school clothes, kids and teens are always on the lookout for the coolest clothing, but thanks to the development of a new plastic-based textile, they could soon mean that in the most literal sense rather than a metaphorical, pop culture one.
The new cloth, developed by researchers at Stanford University and detailed in the latest edition of the journal Science, proved to be more effective than conventional fabrics such as cotton when blocking heat from the sun’s rays, according to the Washington Post and Los Angeles Times.Made from a nanoporous polyethylene, the new clothing enables the body to discharge heat in a pair of ways, making the person feel nearly four degrees Fahrenheit cooler than they would have if they were wearing traditional polyethylene-based athletic wear or cotton clothing, the research team explained Thursday in a statement.
Like ordinary fabrics, the new textile cools people down by letting their perspiration evaporate through the material. Unlike conventional clothing, however, it also allows body heat emitted as infrared radiation to pass through the fabric, which Stanford electrical engineering professor and photonics expert Shanhui Fan said represents “40 to 60 percent of our body heat.”
Since no currently available fabric is 100 percent permeable to this radiation, lead author and associate professor of materials science and engineering Yi Cui told the Post, “If you could, in the summer time, make this radiation go out with nothing blocking it, you would feel cooler.”
Textiles could reduce cost of cooling buildings by 45%
Of course, that isn’t possible for most of us, so the Stanford team set out to create the next best thing: fabrics that could release both perspiration and infrared radiation. They took polyethylene, better known as the clear plastic wrap frequently used in food preparation, and set out to create a new type of textile that takes advantage of some of its desirable properties.
Starting with standard polyethylene, Cui and his colleagues enhanced the material so it would be opaque to visible light (meaning it would not be see-through) as well as making it so that both thermal radiation and water vapor would pass right through nanopores. Once the team developed a single-sheet material, they created a three-ply version which featured two sheets of the tweaked polyethylene surrounding a layer of cotton mesh for additional strength and thickness.
The researchers tested the fabric on a device that simulated how a person’s skin behaves on a hot day, and found that its temperature rose by just 0.8 degrees Celsius – far less than the 2.9-degree spike caused by commercially available polyethylene and the 3.5-degree increase associated with cotton clothing, according to the Times.
In a perspective piece accompanying the article, MIT nanoscientist Svetlana V. Boriskina, who was not involved in the research, explained that this new material could be the catalyst for a new era in which “personalized cooling” replaces the need for air conditioning in buildings, and that if everyone in a workplace wore clothing made out of the new nanoporous polyethylene fabric, it could “save up to 45% of the energy required for the building cooling.”
Image credit: Stanford University