MIT engineers developed self-cooling fabrics from polyethylene, commonly used in plastic bags, that they say may be more sustainable than cotton and other common textiles. Photo by Svetlana Boriskina/MIT
March 15 (UPI) -- Scientists have developed a new strategy for turning plastic into wearable textiles. The breakthrough -- described Monday in the journal Nature Sustainability -- could help ease Earth's growing plastic pollution problem.
Attempts to make plastic textiles have previously faltered as a result of polyethylene's inability to wick away and evaporate moisture.
However, engineers at MIT have managed to weave polyethylene into fibers that absorb and evaporate water more quickly than cotton, nylon, polyester and other common textiles.
The authors of the new paper hope their technology will incentivize plastic recycling.
"Once someone throws a plastic bag in the ocean, that's a problem," Svetlana Boriskina, mechanical engineer at MIT, told MIT News.
"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," Boriskina said.
More than just a plastic pollution solution, researchers suggest plastic textiles could be more eco-friendly over the course of their life cycle than cotton and nylon textiles.
Polyethylene is the world's most common plastic. Its carbon-hydrogen molecules form Teflon-like chains that resist binding with water and other molecules.
"Everyone we talked to said polyethylene might keep you cool, but it wouldn't absorb water and sweat because it rejects water, and because of this, it wouldn't work as a textile," Boriskina said.
Researchers tried anyways, using standard textile manufacturing to turn polyethylene powder into thin fibers.
Scientists were surprised to find the fiber-fabrication process caused the polyethylene to become weakly hydrophilic -- attracting, not repelling, water molecules.
To create wearable textiles, researchers fed their fibers back into the extrude, fusing multiple fibers into threads that could woven together. The fused fibers yielded capillaries capable of absorbing and trapping moisture attracted to the thread's surface.
Both computer models and tweaks to the production process showed the thread's wicking abilities could be improved by altering its diameter and the arrangement of its fibers.
Though the material's wicking ability decreased after getting wet multiple times, scientists found that its wicking properties could be refreshed by both friction and UV light.
"You can refresh the material by rubbing it against itself, and that way it maintains its wicking ability," Boriskina said. "It can continuously and passively pump away moisture."
Researchers were able to color the threads by mixing colored particles with the polyethylene powder prior to the extrusion process. Authors of the new paper suggest the process is more eco-friendly than traditional textile dyeing processes.
Though the polyethylene fibers weakly attract and absorb water, they still don't bind with other molecules, which make them easier to clean -- saving energy that would be otherwise used to power longer, warmer wash cycles.
"It doesn't get dirty because nothing sticks to it," Boriskina said. "You could wash polyethyelene on the cold cycle for 10 minutes, versus washing cotton on the hot cycle for an hour."
Even if polyethylene textiles relied on newly produced plastic, scientists estimate the plastic-derived material would still be more eco-friendly than traditional textiles.
"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 said.
"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," Boriskina said.