MIT engineers have designed a novel elastic yarn made entirely from polyethylene, a widely used plastic, that can be recycled repeatedly without degrading its strength or flexibility. This innovation, detailed in a recent study published in ACS Materials Letters, aims to reduce the massive volume of textile waste, particularly from stretchy fabrics that traditionally rely on non-recyclable spandex blends.
What Happened
The research team, led by MIT mechanical engineering scientist Svetlana Boriskina, developed an elastic yarn composed of a core and sheath made from two different polyethylene-based copolymers. Unlike conventional elastic yarns that combine spandex cores with polyester or nylon sheaths, their yarn is created solely from polyethylene variants that mimic the elasticity and toughness of spandex materials. The fibers were fabricated by melting and extruding pellets of the resin at approximately 350 degrees Fahrenheit, then spun industrially to form the elastic core-sheath yarn.
To verify recyclability, the researchers conducted repeated cycles of melting and respinning the yarn. They demonstrated that after 10 such recycling iterations, the yarn maintained mechanical properties comparable to the original, including tensile strength and flexibility, which are critical for textile applications.
Key Facts
The study was published in ACS Materials Letters and conducted by the MIT Department of Mechanical Engineering. The yarn utilizes polyethylene, a thermoplastic commonly found in everyday products like grocery bags and milk bottles. This work builds on the team’s prior research on spinning polyethylene into yarn and weaving it into garments. The research involved selecting appropriate polyethylene-based resins for the elastic core and fibers seeking similar mechanical properties to spandex.
The yarn fabrication process involved industrial extrusion and spinning techniques, simulating potential scalable commercial manufacturing. Mechanical testing measured the pulling force at which yarns break after repeated recycling. The new yarn offers a recyclable alternative to the 80% of U.S. textiles that currently include spandex, rendering them non-recyclable in conventional systems.
What This Means
This development potentially marks a significant advance in textile sustainability by addressing the persistent recycling challenge posed by spandex-containing stretch fabrics. Since spandex yarns require separation of fibers through complex chemical processes that add cost and environmental hazards, the MIT yarn’s single-chemistry polyethylene composition promises a viable way to close the loop in stretch textile production and recycling. For consumers and manufacturers, this could lead to recyclable, high-performance elastic fabrics that reduce landfill contributions.
Moreover, the approach could catalyze a shift toward circular fashion, where garments can be remanufactured repeatedly rather than discarded. This aligns with growing demands for sustainable solutions in the $2.5 trillion global fashion industry. By maintaining physical performance after multiple recycling cycles, this yarn innovation offers practical utility while mitigating environmental impacts associated with textile waste and microplastic pollution.
Background
Conventional elastic yarn contains a polyurethane-based spandex core wrapped with polyester or nylon fibers, making the materials difficult to recycle together. Though chemical separation methods exist, they are expensive and environmentally unfriendly. Polyethylene’s thermoplastic nature allows melting and reshaping without degrading its properties, which the MIT team leveraged to develop a yarn capable of being recycled without separation.
The foundational polyethylene yarn research was established by this team in 2021 when they produced yarns demonstrating favorable moisture-wicking and cooling properties using polyethylene fibers.
What Remains Unclear
While the laboratory recyclability of the polyethylene yarn is established, questions remain about large-scale manufacturing feasibility, cost competitiveness with current elastic yarns, and long-term durability in diverse textile applications. The full lifecycle environmental benefits and potential for integration into existing recycling infrastructure have yet to be evaluated comprehensively.
What Comes Next
The researchers plan to advance the yarn’s production to industrial-scale spools suitable for textile mills, enabling the knitting and weaving of garments from this new material. Further testing on textile performance and integration into recycling streams will be necessary before commercial deployment. The team also envisions that garments made from this yarn could be collected and recycled repeatedly, supporting sustainable circularity in fashion.
Sources
This article is based on reporting and publicly available information from the following sources:
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