You Could Soon Be Wearing the Stuff of Plastic Grocery Bags

MIT engineers have turned polyethylene into a lightweight, moisture-wicking fabric.

polyethylene fabric
New fabrics made from polyethylene.

MIT (used with permission)

Scientists at MIT have discovered a way to turn polyethylene – the stuff of plastic wrap and grocery bags – into a wearable fabric that has a surprisingly low environmental footprint. In a study published in the journal Nature Sustainability, the researchers explain how they managed to overcome a longstanding barrier to using polyethylene as a wearable fabric – its anti-wicking properties that lock in water and sweat. 

Now, however, they have managed to spin polyethylene into fibers that are silky-soft and lightweight and do manage to absorb and evaporate moisture faster than cotton, nylon, and polyester. A press release from MIT explains how the scientists did this:

"They started with polyethylene in its raw powder form and used standard textile manufacturing equipment to melt and extrude polyethylene into thin fibers, similar to turning out strands of spaghetti. Surprisingly, they found that this extrusion process slightly oxidized the material, changing the fiber’s surface energy so that polyethylene became weakly hydrophilic, and able to attract water molecules to its surface." 

Every test revealed a material that wicks away moisture faster than other common textiles, although it does lose its hydrophilic tendency after repeated wetting. This can be stimulated once again using friction. As study co-author Svetlana Boriskina said, "You can refresh the material by rubbing it against itself, and that way it maintains its wicking ability. It can continuously and passively pump away moisture."

From an ecological perspective, this material shows promise. It is colored by adding particles to the raw powder form prior to extrusion, which means it takes on the color without the addition of any dyes or water. Said Boriskina, "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 down, centrifuge, and recover the particles to use again."

The team used a life cycle assessment tool to conclude that producing fabric from polyethylene uses less energy than cotton or polyester. It has a lower melting point than other synthetic materials, so it doesn't need to be heated up as much to work with it. Boriskina said, "Cotton also takes a lot of land, fertilizer, and water to grow, and is treated with harsh chemicals." Furthermore, the polyethylene fabric repels dirt, does not require frequent washing, and dries rapidly.

The idea of swathing oneself in what's essentially plastic, however, may not appeal to many readers. When Treehugger asked Boriskina what the material would be used for and how it would feel, she explained that it could be both an athletic and leisure fabric: "Athletic apparel companies hopefully [would become] early adopters of this technology because of the added value in passive cooling that can help to increase performance. The fabric has a smooth silky texture and is cool to touch, meets industrial standards, and should be comfortable to wear."

As for any health concerns about wearing polyethylene (PE) next to the skin, Boriskina pointed out that it is biologically inert and can be softened without plasticizers. 

"PE is one of the most common materials used in medical implants because it does not degrade in the body. If it's safe to put under the skin, we think it should certainly be safe to put it over the skin. In fact, owing to its chemical inertness, polyethylene is considered safe for use in cosmetic formulations. As we demonstrate in the manuscript, PE yarns can be spin-dyed with a variety of organic and inorganic colorants, which can be carefully chosen to reduce any potential health risks."

It's unclear whether or how the material sheds microplastic fibers in the wash – a serious concern with synthetics of all kinds – and Boriskina told Treehugger that that is the subject of the team's current work. "[It will be] published separately hopefully soon, and we believe that properly engineered PE fabrics can provide a sustainable upstream solution to the microplastic shedding problem." 

When asked whether having an "upcycled" solution for plastic grocery bags would make people more inclined to keep using them at a time when we need to be phasing them out, Boriskina said she hopes not and that, in fact, "reusable woven or knitted PE grocery bags that are easy to wash" could be a good application for the new material.

It is intriguing research that materials scientist Shirley Meng (not involved in the study) describes as surprising but convincing: "Based on the data presented in the paper, 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." 

While I am an advocate of wearing natural plant-based fibers whenever possible, the fact remains that there's a time and place for stretchy synthetic materials. (I do love my leggings.) If those can be made from a material like polyethylene, with less environmental impact, then that's a definite improvement over current conventional synthetics.

View Article Sources
  1. Alberghini, Matteo, et al. "Sustainable Polyethylene Fabrics with Engineered Moisture Transport for Passive Cooling." Nature Sustainability, 2021, doi:10.1038/s41893-021-00688-5