Under Armour and Celanese have unveiled a fresh type of stretch fibre that they say could provide a more easily recyclable alternative to elastane – and they are keen for wider industry adoption.

Sportswear relies on stretch. It is one of the key attributes that makes clothing comfortable and form fitting. Spandex, or elastane, is made from polyurethane and polyethylene glycol and can stretch multiple times and return to its original shape; it is most often blended with polyester or cotton. 

However, it does present some challenges when it comes to a garment’s end of life. These fibres cannot be easily separated, so recycling becomes an issue. This is one of the “longstanding sustainability challenges” that US brand Under Armour sought to tackle several years ago when it teamed up with US-based materials developer Celanese, through a research partnership with North Carolina State University, to develop an alternative.

“Our companies share a commitment to innovating at the materials level to improve products, in this case textiles,” Kyle Blakely, senior vice-president and head of innovation at Under Armour, tells WSA. “We saw an opportunity to team up to begin to tackle a longstanding sustainability challenge in our industry. We have a super-functional, aligned approach to complicated development and act as one team, even though we are both part of large companies.”

Celanese Corporation produces specialty materials and chemicals, with production in North America, Europe and Asia. It is one of the world’s largest producers of acetyl products and creates high-performance engineered polymers that are used in a variety of applications. The teams brought different expertise to the programme: Celanese provided technical know-how in polyester and elastomer chemistry and processing, and Under Armour added knowledge of fabrics, including knitting and dyeing, and the end consumer.

The resulting fibre, Neolast, is described as as offering powerful stretch properties along with durability, comfort and high levels of moisture wicking. It is produced using a solvent-free melt-extrusion process, which offers “increased production precision”, allowing spinners to dial power-stretch levels up or down and engineer fibres to meet varying fabric specifications.

Moisture wicking and durable

Initial tests are showing impressive results, according to the companies. Fibres can be knitted or woven into stretch fabrics at percentages from 2% and 40%, and blended with polyester, cotton, nylon, linen, rayon and silk. In a single-jersey fabric made with 84% polyester and 16% Neolast fibres (versus 16% elastane), Celanese claims there is three times more stretch power, plus improvements in overall durability. The fibres are unlikely to unravel, pill, degrade or yellow and can be dyed the full spectrum of colours. “We wanted Neolast to provide both performance and sustainability benefits,” Peter Wing, global marketing director for industrial, medical and consumer products at Celanese, tells us.

One of  the “key advantages” over elastane would be the potential for recycling, as the fibres are made from recyclable thermoplastic polymers rather than thermoset-based elastane. “This means it can be reprocessed much more easily,” adds Mr Wing. “The potential for recycling blended fabrics made with Neolast is especially strong with polyester. As an elastoester material, Neolast polymers are part of the polyester family. It provides stretch performance in a common chemistry, which enables a mono-material garment.”

The companies feel this is such a step forward, they are offering the product to the wider industry, to help develop and scale it, and to boost overall impact. Celanese is working with brands and manufacturers on testing and development programmes, “exploring the potential of the fibres to improve the compatibility of stretch fabrics with future recycling systems and infrastructure”.

Redesigning machinery

How would this new fibre fit into existing manufacturing set-ups? Celanese admits some redesign modifications are required to traditional polyester spinning equipment, and is working with some spinners to implement this. There is also the option of buying new melt extrusion spinning machines that have been designed to work with the proprietary technology. “It’s still early, but our current priority is to make this material widely available to the apparel industry at the right price point, and we are excited to build on the work that’s already begun with a range of brand owners and value chain partners to unlock its full potential,” says Mr Wing.

Addressing the end-of-life issue, Neolast will also be available with a bio-content option. This falls under Celanese’s ECO-B product portfolio, which uses renewable bio-content on a mass-balanced basis. ‘Mass balance’ is an accounting principle that makes it possible to track the amount and sustainability characteristics of circular and/or bio-based content in the value chain. Bio-based feedstocks can come from various types of organic waste. “The ECO-B materials used are chemically identical as a drop-in solution to our standard materials,” explains Mr Wing.

Target

One of the drivers for the collaboration was Under Armour’s own sustainability targets. It has committed to enable recyclability for its clothing and accessories by 2030. This will be aided by eliminating 75% of spandex by the same year. “Under Armour’s sustainability strategy is designed to address the impact of our business across three key pillars: Products, Home Field and Team,” explains Mr Blakely. “Neolast embodies our programme’s focus on performance-driven innovations that align desirability, performance and sustainability through innovation.” 

Both companies stress it is still an early stage, but they are excited about its performance, solvent-free production process and the potential for recyclability. Under Armour will be making more announcements about Neolast in the coming months. “We believe Neolast has the potential to solve a critical challenge for the apparel industry,” concludes Mr Wing, “enabling the stretch performance consumers demand, along with an improved sustainability footprint.”

Neolast can be used to add stretch for multiple sectors, including sportswear and swimwear. Celanese is also liaising with denim mills to begin R&D with a view to  using it in jeans.
All credits: Under Armour

Share this story: