Engineers at MIT have developed self-cooling fabrics from polyethylene, a material commonly used in plastic bags. The team has published their findings in the journal Nature Sustainability.
Polyethylene is thin and lightweight, and could keep you cooler than most textiles because it lets heat through rather than trapping it in. But polyethylene would also lock in water and sweat, as it’s unable to draw away and evaporate moisture. This antiwicking property has been a major deterrent to polyethylene’s adoption as a wearable textile.
Now, MIT engineers have spun polyethylene into fibers and yarns designed to wick away moisture. They wove the yarns into silky, lightweight fabrics that absorb and evaporate water more quickly than common textiles such as cotton, nylon, and polyester.
They have also calculated the ecological footprint that polyethylene would have if it were produced and used as a textile. Counter to most assumptions, they estimate that polyethylene fabrics may have a smaller environmental impact over their life cycle than cotton and nylon textiles.
The researchers hope that fabrics made from polyethylene could provide an incentive to recycle plastic bags and other polyethylene products into wearable textiles, adding to the material’s sustainability.
“Once someone throws a plastic bag in the ocean, that’s a problem. But those bags could easily be recycled, and if you can make polyethylene into a sneaker or a hoodie, it would make economic sense to pick up these bags and recycle them,” says Svetlana Boriskina, a research scientist in MIT’s Department of Mechanical Engineering.
Smaller ecological footprint
“Polyethylene has a lower melting temperature so you don’t have to heat it up as much as other synthetic polymer materials to make yarn, for example,” Boriskina explains. “Synthesis of raw polyethylene also releases less greenhouse gas and waste heat than synthesis of more conventional textile materials such as polyester or nylon. Cotton also takes a lot of land, fertilizer, and water to grow, and is treated with harsh chemicals, which all comes with a huge ecological footprint.”
In its use phase, polyethylene fabric could also have a smaller environmental impact, she says, as it would require less energy to wash and dry the material compared with cotton and other textiles.
“It doesn’t get dirty because nothing sticks to it,” Boriskina says. “You could wash polyethyelene on the cold cycle for 10 minutes, versus washing cotton on the hot cycle for an hour.”
The team is exploring ways to incorporate polyethylene fabrics into lightweight, passively cooling athletic apparel, military attire, and even next-generation spacesuits, as polyethylene shields against the harmful X-ray radiation of space.
Photo credit: John McGarvey, flickr/Creative Commons
