Mar 16 2021
Fabrics of the future with self-cooling and water evaporating properties could be made from polyethylene — a material commonly found in plastic bags.
Image Credit: Emilija Miljkovic/shutterstock.com
Researchers from the Massachusetts Institute of Technology (MIT) have found a way to transform polyethylene (PE) into a viable fabric for clothing. The thin, lightweight plastic is a key ingredient in many items, most predominantly plastic carrier bags.
The team suggests that the lightweight fabric they have created could be of particular use for sportswear like vests, sneakers, and leggings because of the self-cooling properties granted to it by the use of PE.
The PE used in the fabrics can be dyed in different colors, meaning that it can also be reused in new garments. Because the fabric can be recycled and used to create entirely new clothes, the researchers, led by Svetlana Boriskina, from MIT’s Department of Engineering, believe that it is more environmentally friendly than most of the textiles we currently rely on.
This environmentally friendly quality is further built upon by the fact that the fabric can be efficiently washed in cold water, the team adds.
This means that the team’s discovery could not only make the fashion industry more sustainable but could also radically cut down plastic pollution — one of the planet’s most pressing environmental concerns — by offering an incentive to recycle.
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.
Svetlana Boriskina, Researcher, Department of Engineering, MIT
The team’s research is documented in a paper published in the journal Nature Sustainability¹.
Keeping Cool and Dry with Polyethylene Fabrics
The idea of transforming polyethylene into a fabric may seem a bit odd, but in some ways, its properties actually make it a very natural choice for such uses.
One of the main qualities cited by the team is the fact that PE can allow heat to pass through it. This means it could be used to create a textile that doesn’t trap heat next to the body, resulting in ‘self-cooling’ clothing.
Thus far, PE textiles have been prevented from being widely adopted in clothing because, a PE-based textile would allow heat to flow away from the wearer, it would also simultaneously lock moisture in.
In short, that means the wearer’s sweat and any other moisture would be locked against their skin by the PE-derived clothing.
“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,” explains Boriskina.
However, MIT researchers have found a way to spin PE into fibers that are specifically designed to combat this ‘anti-wicking’ property by carrying moisture away. The team started in PE in raw powder form, which they melted and turned into thin fibers.
This process had an unexpected side-effect; it slightly oxidized the material. This had the knock-on effect of making the PE slightly hydrophilic — it started to attract water towards its surface.
By weaving the fibers into a lightweight yarn, the team discovered that the spaces between the individual fibers could absorb water. Not only this but by arranging the fibers in specific ways, they could optimize this wicking ability.
Testing this ability, the researchers found that their PE enhanced fabric wicked away water and evaporated it more quickly than man-made textiles like nylon and polyester and natural materials like cotton.
Repeated usage did seem to deplete the fabric’s wicking ability, but the scientists discovered that this could be regenerated by exposing the material to UV light or even via the simple application of friction.
“You can refresh the material by rubbing it against itself, and that way, it maintains its wicking ability,” continues Boriskina. “It can continuously and passively pump away moisture.”
Stain Resistance Not Color Resistance
The fact that PE resists binding with other molecules means that it is naturally stain-resistant. As a result, it can be successfully washed in colder water than many other fabrics, thus saving energy and providing another bonus to the environment.
“It doesn’t get dirty because nothing sticks to it,” Boriskina explains. “You could wash polyethylene on the cold cycle for 10 minutes, versus washing cotton on the hot cycle for an hour.”
Yet, this resistance comes with a downside. Whilst the fibers won’t bind as well with chocolate ice-cream, they also won’t bind with inks and dyes, meaning such fabrics should be hard to color. Fortunately, the team has a fix for this too.
The team found they could color the fabric by adding colored particles to the PE powder before their treatment begins. The result is the color being ‘baked in’ to the fibers as they form.
We don’t need to go through the traditional process of dyeing textiles by dunking them in solutions of harsh chemicals. We can color polyethylene fibers in a completely dry fashion, and at the end of their life cycle, we could melt them down, centrifuge them, and recover the particles to use again.
Svetlana Boriskina, Researcher, Department of Engineering, MIT
Thus, the researchers found that the PE textiles they created required less energy and less chemical treatment than traditional fabrics meaning they have a significantly smaller environmental footprint.
The Sky is the Limit For PE Textiles
The next step for the team’s PE enhanced fabric is finding a way to incorporate it into sporting gear, military uniforms, and a wide range of other garments.
The team even suggest that the fabric could find its way into the next generation of spacesuits. As space agencies like NASA embark on a new era of manned space exploration, the PE-enhanced textile could be used to protect astronauts from harsh X-ray radiation.
“Though a surprising finding, I think the design of experiments and the data are quite convincing,” says Shirley Meng, a materials scientist at the University of California, San Diego, not connected to the research project. “The particular PE fabric reported here depicts superior properties than those of cotton.
“The main point is that recycled PE can be used to make textile, a product with significant value. This is the missing piece of PE recycling and circular economy.”
Source
¹ Alberghini, M., Hong, S., Lozano, L.M., et al, [2021], “Sustainable polyethylene fabrics with engineered moisture transport for passive cooling,” Nature Sustainability, [https://doi.org/10.1038/s41893-021-00688-5]