Recyclable Elastic Yarn Could Replace Spandex in Sustainable Clothing

A new type of recyclable elastic yarn could make stretchy workout clothes and other flexible garments easier to recycle. Developed by engineers at MIT, the yarn is designed to be as strong and stretchy as fabrics made with traditional spandex, while being produced entirely from polyethylene.

The research, published July 25 in ACS Materials Letters, describes a potential spandex alternative for sustainable textiles. Polyethylene is the plastic commonly used in products such as milk jugs and single-use grocery bags.

Most stretchy clothing currently combines spandex — a highly elastic but relatively weak polyurethane fiber — with stronger materials such as polyester or nylon. While this combination provides comfort, flexibility and durability, it creates a major recycling challenge because the different fibers are difficult and expensive to separate.

When mixed-fiber clothing reaches the end of its useful life, it is rarely recycled. The chemicals required to separate the materials can be hazardous, and many garments are instead sent to landfills or incinerators. An estimated 80% of textiles sold in the United States contain spandex, according to study co-author Svetlana Boriskina, a research scientist in MIT’s Department of Mechanical Engineering.

How the polyethylene yarn works

To create the new yarn, the MIT researchers used two forms of polyethylene. A soft, spring-like polyethylene forms the stretchy inner core, similar to a rubber band. Around it, the team wrapped a stronger polyethylene fiber that behaves more like fishing line.

The outer fiber is tightly coiled around the elastic core, creating a spring-like structure that allows the yarn to stretch and recover. Because both components are made from the same type of plastic, the material does not need to be separated into different fibers before recycling.

Polyethylene is also considered one of the world’s most widely recycled plastics. This compatibility could make it possible to recycle garments made from the yarn through a simpler, lower-energy process.

Recycled yarn maintained its strength

In laboratory tests, the researchers melted a spool of the polyethylene yarn and spun it into new yarn 10 times. After every recycling cycle, they tested the material’s strength and performance.

The recycled yarn retained the same performance as the original material in each test. It also outperformed commercial spandex-polyester yarn in maximum load, meaning the polyethylene-based yarn could withstand more force before breaking.

Could entire garments become recyclable?

The researchers have previously shown that lightweight polyethylene fibers can be engineered to provide additional features, including cooling, moisture wicking and stain resistance. These properties could make the material suitable for activewear, sportswear and other performance clothing.

The approach could eventually extend beyond fabric. Buttons, zippers and buckles made from compatible plastics might allow entire garments to be melted down and remade without being dismantled first.

Although the recyclable elastic yarn is still in the research stage, it could offer a promising path toward circular fashion by reducing the need for mixed-fiber clothing and improving the recyclability of stretchy textiles.