Xeros Washing Machine Uses Nylon Polymer Beads Instead of Water to Clean Clothes

The Xeros washing machine looks like your standard washer, but those “suds” peeking out of the door are anything but soapy. Xeros, a company based in Rotherham in the UK, is looking to revolutionize domestic and industrial laundry alike with “bead cleaning.” The technology, the company claims, is not only superior to traditional soap and water but also environmentally friendly. Already with customers in Europe and the US, Xeros may be poised to make a big splash in the world of laundry with its washload full of lentil-sized polymer beads.

Xeros is a six-year-old spinoff from the University of Leeds, where textile chemist Stephen Burkinshaw had the original inspiration to reverse the dyeing process. Instead of adding pigment to textiles, Burkinshaw and his students experimented with removing pigment—that is, stains. Nylon readily takes up dye, and forming the polymer into round beads yielded the most effective stain extractor. The beads’ surface area, weight, and chemistry have since been engineered with regard to four independent factors—temperature, chemistry, time, and mechanics—that affect the washing process.

The proprietary Xeros washer looks like a standard front-loading machine (the domestic version, slated for a 2015 US launch, will have a smaller footprint than the current commercial instantiation). About 50 kilograms of beads, held in a wet sump below the machine, are pulsed in with water through the top of the drum. The beads fall out of the drum and then recirculate. The company’s chief science officer, Stephen Jenkins, likens the process to laundry taking a shower—not a bath—in beads. The shower analogy is apt in terms of water savings as well. Xeros claims a 70% reduction in water usage compared with standard washing. And because bead cleaning works in cold water (20 °C), heating is not required, which cuts energy use in half by Xeros’s estimate. The amount of special detergent used in the wash is also about 50% of what would normally be used, Jenkins says.

The one and a half million or so beads used per load constitute the fundamental ingredient in the cleaning cocktail. Xeros now has two main bead compositions—polyester (specifically, polyethylene terephthalate) and nylon (nylon 6,6). The mechanical action of the beads passing over clothing removes soil, and the weight of the beads reduces creasing by pinning the fabric down. But it is the beads’ polymeric structure that attracts and traps dirt. Thanks to the presence of polar groups, the beads adsorb solubilizable stains. Nylon excels at “vagrant dye capture” because of a negative glass transition temperature that creates free volume within the polymer’s structure and allows absorption and diffusion of stains into the bead itself. In that way, Xeros washes are also resistant to dye transfer between colors and whites. In retail dry cleaning, “the ability to mix colors and whites can save considerable sorting time,” says Jenkins. “With the chemistry that we are developing for generation-two beads, we can get the dye capture to be almost perfect.”

*Also see http://youtu.be/PXYwKtDEx4w

Read more here http://scitation.aip.org/content/aip/magazine/physicstoday/news/10.1063/PT.5.5008

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