The findings were detailed in the journal ACS Materials Letters by Svetlana Boriskina, a research scientist in MIT’s Department of Mechanical Engineering, along with first author SeongHyeon Kim and colleagues Duo Xu, Volodymyr Korolovych, Domingo Flores-Hernandez, Kaniz Moriam, and Daniel Braconnier.
The MIT team demonstrated that garments produced from this newly designed yarn can be melted down after use and respun into new fibre or reused to make other plastic components like buttons and belt buckles.
Made from widely used plastics like milk bottles and grocery bags, the new yarn is said to feel like traditional sewing thread and can be woven into stretchy, lightweight clothing.
In laboratory testing, the researchers subjected the yarn to repeated recycling cycles, finding that even after being melted and respun 10 times, the material retained its original strength and flexibility.
The researchers believe that the new yarn may serve as an alternative to elastic spandex-polyester or spandex-nylon yarns, which are typically produced from a blend of fibres that cannot be recycled together.
Boriskina said: “Eighty per cent of textiles on the US market currently contain some amount of spandex, which makes them nonrecyclable. There’s no widely adopted technology now that recycles textiles into textiles. With our new yarn, we hope to change that.”
The research stems from earlier work in which Boriskina’s team produced polyethylene-based yarns with moisture-wicking and stain-resistant qualities.
To create the yarn, the researchers selected a polyethylene-based resin for the core to provide flexibility, and a different, stiffer resin for the sheath.
Pellets of each resin were sourced from a chemical supplier and processed by heating them to a temperature above their melting point, approximately 350 degrees Fahrenheit.
The molten material was then extruded through fine openings to form thin fibres.
According to the researchers, the polyethylene yarn can be produced at an industrial scale and woven into textiles in the same way as spandex fibres.
After use, garments made from this yarn could be recycled by melting and respinning, supporting a circular approach within the fashion and textile sector.
“Hopefully it will prevent the need for making more and more textile materials, because you can keep recycling a large portion of it,” Boriskina added.
Funding for the study was provided in part by the DEVCOM Soldier Centre via the US Army Research Office, the Office of Naval Research Global, and the MIT Portugal Programme.
