Every year, millions of tons of old clothing end up in landfills because most textiles are difficult or impossible to recycle.
While plastic bottles and aluminum cans are commonly recycled, clothing often has no similar pathway.
Now, engineers at the Massachusetts Institute of Technology (MIT) have developed a new type of stretchy yarn that could help change that by making clothes much easier to recycle.
The research, published in ACS Materials Letters, describes a recyclable yarn that is as strong and stretchy as traditional spandex-based yarns.
Unlike today’s elastic fabrics, the new material can be melted down and turned back into fresh yarn over and over again without losing its performance.
The need for better textile recycling is growing. The average American throws away about 81 pounds of clothing each year.
Together, that adds up to more than 11 million tons of textile waste annually, with most of it ending up in landfills or being burned.
One major reason clothing is difficult to recycle is the widespread use of spandex. Around 80% of textiles sold in the United States contain at least some spandex, which gives fabrics their stretch.
Most stretchy clothing combines a spandex core with an outer layer made of polyester or nylon. These different materials are tightly bonded together, making them extremely difficult to separate for recycling.
Although chemical methods exist to separate these materials, they are expensive, complicated, and often involve chemicals that can harm the environment. As a result, most stretchy clothing is simply thrown away.
The MIT team took a different approach. Instead of combining different types of plastics, they created both the stretchy center and the stronger outer layer using different forms of polyethylene. Polyethylene is one of the world’s most common plastics and is already widely used to make grocery bags, milk bottles, toys, pipes, and many other products. Because it is a thermoplastic, it can be melted and reshaped many times.
The researchers carefully selected two types of polyethylene with different properties. One produces a soft, flexible fiber for the center of the yarn, while the other creates a stronger outer layer that protects the core. Together, the two materials give the yarn the stretch and strength needed for clothing while remaining fully recyclable because they belong to the same plastic family.
To make the yarn, the plastic pellets were heated until they melted and then pushed through tiny openings to create very thin fibers, much like squeezing dough through a pasta maker. These fibers were then spun together using standard industrial equipment to create an elastic yarn suitable for knitting and weaving.
The researchers tested the yarn by repeatedly recycling it. They spun the material into yarn, melted it down, and spun it into new yarn ten separate times. After each cycle, they measured its strength and flexibility. Even after ten rounds of recycling, the yarn remained just as strong and stretchy as the original material and performed similarly to conventional elastic threads.
Because the entire yarn is made from compatible polyethylene materials, it can be recycled without separating different fibers first. At the end of a garment’s life, the fabric could simply be melted and turned into new yarn, or even molded into products such as buttons, buckles, or other plastic accessories.
The researchers believe their new yarn can be produced on an industrial scale using existing manufacturing equipment. If widely adopted, clothing made from this material could support a more circular fashion industry, where garments are repeatedly recycled instead of discarded.
By keeping valuable materials in use for much longer, the technology could significantly reduce textile waste and lower the demand for producing new synthetic fibers, helping make the fashion industry more sustainable.
