Textile-to-textile recycling is making progress for items made from pure cotton or polyester, and blends of both. Fewer solutions are available for fabrics made from blends of other fibres. Those containing elastane are considered the most challenging. Yet they are ubiquitous. Concerned parties are investigating promising solutions.  

Is elastane a contaminant or a potential revenue stream? Spandex, as it is also called, is present in small concentrations in apparel, but it plays a huge role in a garment’s fit, comfort and longevity. There is little reason to believe that for the purpose of building a circular fashion system, where fibres remain in the loop for multiple lifecycles, brands or designers will resist the temptation to continue using elastane.

A report on the presence of elastane in clothing in the UK found it to be present in 34% of millions of items available for sale online. Matter to Market, a consultancy specialising in bringing next-gen fibres to market, screens the presence of different fibre families in apparel, drawing on data collected by Edited, a London-based retail intelligence platform.

By product category, the stretch fibre is mentioned on the care and composition labels of 52% of jeans and 27% of T-shirts, sweatshirts and tank tops; it is in 73% of swimwear and 86% of underwear. By brand, the stretch fibre’s presence rates high at ultra-fast fashion labels Shein (47%) and PrettyLittleThing (46%). In activewear, few companies are cited, but it makes up one-third of products sold by adidas performance (36%), Reebok (34%) and Hummel (33%). 

A desire for elasticity has led to spandex becoming ubiquitous across all product categories, extending, in all probability, their useful life. This adds value. However, its presence in clothing that is no longer wanted or wearable, and could be recycled, is considered a contaminant. Garments and fabrics containing elastane must be removed from feedstock intended for mechanical recycling. The stretch fibre forms a spiderweb-like substance that clogs up shredding machines. Some can accept elastane under a certain threshold, 5% generally, but its presence may lower the value of the recycled fibres. Then there are core-spun stretch yarns to consider, as they pose another issue. These yarns are made from an elastane filament that is covered by a different fibre, often cotton or nylon. Automated sorting devices cannot detect the presence of spandex, and, again, it risks contaminating feedstock both for chemical and mechanical recyclers. 

Dr Alberto Ceria, a textile and chemical engineer at The Lycra Company’s R&D department, believes recyclers are approaching the issue from the wrong standpoint. “Elastane is everywhere, but its value is overlooked,” he said at a talk at Performance Days talk this March. “In a product made from 70% polyester and 30% elastane, the value lies in the 30% elastane, not in the polyester,” he claims. 
Elastane producers, such as The Lycra Company and Hyosung, are committed to making the apparel industry more sustainable and working with recyclers to find solutions for fabrics made from their fibres. “Most recyclers require feedstock that is 100% polyester, cotton or nylon. Yet this does not reflect the reality of textile waste,” Dr Ceria tells Sportstextiles. “Elastane should not be considered a contaminant, as it is always used for a reason. Without it, a fabric may not have been made in the first place.”  He argues that, rather than discarding the elastane portion as waste, retrieving the stretch fibre would increase a recycler’s yield, making its business more sustainable and economic.

To encourage recyclers to find solutions for retrieving elastane, the maker of Lycra fibre is working closely with selected chemical recyclers, specifically those who recover their target hard fibre without destroying the stretch fibre. “If we want to make an elastane yarn from recycled material, it is preferable to preserve the polymer’s chemistry,” he says. The Lycra Company has been testing this scenario, taking recycled elastane and blending it with virgin polymer to meet its performance specifications. 

Among the various chemical processes in development, Dr Ceria sees the most promise in those operating in mild conditions. “Certain chemical processes and most biological or enzymatic methods work well and have minimal impact on the elastane’s structure,” he says. However, pending the scaling of a fibre-to-fibre recycling infrastructure, “the amount of product we can access today is limited”. 
Korean textile conglomerate Hyosung, the world’s largest elastane producer, is also working with chemical recyclers and investigating post-industrial and post-consumer waste. “One of the greatest technical challenges in spandex recycling is removing dyes and finishing agents attached to the various primary fibres,” says Simon Whitmarsh-Knight, Hyosung Textiles’ global sustainability manager. “These impurities act as contaminants and must be eliminated to ensure stable recovery and downstream processing of high-purity spandex.” Due to the variety of additives and colourants, he does not foresee “a one-size-fits-all solution”.

At this stage of development, the learning curve is wide open, and Hyosung is pursuing a hybrid strategy. Beyond the technical feasibility of recycling stretch fabrics, Mr Whitmarsh-Knight says that cost-efficiency is the most critical factor. “No matter how advanced the technology may be, commercialisation is not viable unless the process can achieve levels of economic performance that the market is willing to support.”

Separating without retrieving 

The result of more than ten years of research and development, Italian nylon producer Aquafil has set up a demonstration plant that can separate elastic fibres from nylon fabrics. In 2013, it launched a research project with Georgia Tech University to explore solutions for recycling mixed fibre stretch fabrics. A patent was filed, but was found difficult to scale. The company’s R&D teams pursued their work, filing another patent in 2022 that brought it closer to the long-sought solution, leading to the pilot plant now in operation in Slovenia, where the company’s Econyl recycling facility is located. Aquafil has not revealed its capacity nor yield, and research is ongoing to refine the process and achieve industrial scale. 

Aquafil’s separation technology removes elastane from polyamide 6 and is also said to do so for PA6.6 and polyester blends. The recovered nylon 6 is then chemically broken down to the original caprolactam monomer. As for the elastane content, a company representative says that Aquafil is “investigating and performing different tests for the use of separated elastane in various applications, with promising results”. 

Swimwear, activewear and intimate apparel are generally made from blends of polyamide 6 and elastane, the stretch fibre constituting around 20% of the blend. This has inspired Jo-Anne Godden, owner of swimwear and activewear brand RubyMoon, to seek a circular solution for this specific market segment. Originally from the UK, Ms Godden is now based in Catalonia. She has been working on this project for the past four years. Through her new venture, RubyLab, she says she has found a low-cost and versatile method for recycling pre- and post-consumer polyamide 6-elastane materials, and she is now planning to launch a pilot. 

In RubyLab’s solution, textile waste is fed into a small reactor where the nylon is separated from the elastane. “The equipment is not new; it has been around for some 20 years, but this is the first time it is being used for textiles,” says Ms Godden. “The process is gentle and uses no hazardous chemicals, only water, low pressure, and a bit of magic.” It does not revert the fibres back to monomers, which she points out makes her solution less energy-intensive, and yields nylon pellets that can be used to make new fibres. The elastane is not retrieved, for now. “But we obviously want to recycle 100% of the materials,” she adds. The device can fit into a shipping container and can thus be located close to manufacturing and recycling centres. “Our process is designed to be agile and versatile. We want to install small reactors in places where there is feedstock; this is where the problem lies.” It would enable manufacturers to recycle their waste on site at little cost. 

Ms Godden is also looking to change the design of swimwear and activewear to increase yields and streamline circularity and has developed a prototype. “We need to design garments that can be fed into our system without disassembly.” Among the changes she recommends are switching sewing threads from polyester to nylon and choosing nylon for linings instead of polyester. She is looking forward to collaborating with brands to ensure that all components are compatible with RubyLab’s recycling process. 

The multifibre challenge 

Materials made from mixed fibres are a challenge for all textile-to-textile recycling technologies, though, as Dr Ceria has said, they are part of the reality of much post-industrial and post-consumer waste. Whatever the technology, mechanical, chemical or enzymatic, multifibre blends will reduce the value of ‘pure’ recycled materials. Any item containing acrylic, elastane or manmade cellulosics needs to be removed from feedstock to ensure efficient recycling.

Recyclers are working on solutions, specifically for the ever-ubiquitous elastane. Re&Up, part of Turkey-based Sanko, has developed a technology that can handle post-consumer and post-industrial textile waste, including garments with elastane. “Rather than requiring elastane to be sorted out beforehand, our process is capable of identifying and extracting it during the recycling stages,” says Re&Up general manager, Andreas Dorner. After an initial mechanical stage, the stretch yarn is separated from other fibres using a thermo-chemical process. “This enables us to isolate components such as elastane, polyester and colourants, while preserving the integrity of the cotton fibres,” he explains. The elastane is then rerouted for use in non-textile applications, such as in the automotive industry. He says the company is in conversation with elastane producers to explore pathways for integrating this elastane into circular textile systems in the future. “On average, the elastane content in the material we process is around 3% to 4%,” he notes.

Earth Protex, a company based in Canada, with divisions in China, Portugal and the US, specialises in thermomechanical recycling. It is also developing a technology to recycle mixed fibres. The Separation Technology of Mixed Polymers (or STOMP) is a water-free process that removes dyes, auxiliaries and chemicals, and also elastane. “In our recycling process, the elastane, like the polyester, is recovered in polymer form, not monomer, so it can be used in a number of applications,” says Samuel Goldstein, chief operating officer. The company is not considering using the recovered elastane for textile applications. “We believe it has high enough value for non-textile applications.” The system, once finalised, will be used as a bolt-on pre-processing technology which will be installed in the company’s Tex2Tex TMR manufacturing facilities. 

Ravel, a recycling technology start-up based in Seattle, says its Purification Recycling technology can handle any amount of elastane in the textile waste it processes. “Our pilot plant is running production on polyester-elastane blends, and no elastane fibre needs to be removed from the feedstock we receive from our brand and manufacturing partners,” says co-founder and CEO, Zahlen Titcomb. He points out that elastane content in stretch clothing and fabrics can reach 20% by mass.

“From economic and circularity perspectives, our focus is on recovering as many materials as possible from the feedstock. A core design principle at Ravel since the beginning has been the use of non-destructive methodologies. While many recycling approaches rely on energy- and cost-intensive processes to break polymers down and rebuild them, we believe the most efficient path is to preserve the inherent value of existing polymers and instead purify individual components for efficient recovery,” he tells Sportstextiles. 

Re:lastane, a chemical recycling method patented by Qingdao Amino Materials Technology, a Chinese company, is said to be a mild process that only targets the polyester fibres, which are broken down into monomers. “The process is so gentle that the elastane thread is left intact. When the recycling process is finished, two materials are ready to be re-made into regenerated garments,” the company claims. Founded in 2020, it won a Global Change Award, H&M Foundation’s innovation challenge, in 2022. 

Japan’s Teijin Frontier also claims to have developed a recycling method for stretch fabrics and garments. Before chemical recycling, a pretreatment phase using a special processing agent removes the elastane fibre and all other foreign materials such as dyes. The company says the agent “swells the PU-elastane fibres”, breaks their chemical bonds and dissolves them. Tests to optimise the solution have been ongoing since October 2022.

A matter of proportion?

The prospect of recycling all types of textile waste, including those troublesome multifibre blends, is not as bleak as expected. The pervasiveness of elastane in today’s clothing, for sports and everyday apparel, is such that solutions do need to be found. However, picking out clothing and fabrics with high elastane content from those with only 1% will complicate operations for recyclers.

Tim Cross, founder of Project Re:Claim and the Circular Textile Foundation, notes that many items of clothing could be readily recyclable “if a few minor changes were made, without altering the performance of a garment”. One such change would be to reduce elastane content from 6% to 5%, which would allow stretch apparel to go through many mechanical and thermomechanical recycling processes. But to optimise yields, and enable manufacturers of elastane to retrieve recycled material, the more elastane recovered the better. “In clothing with low elastane content, we understand that it will often be lost,” notes Dr Ceria. 

Aquafil’s separation technique retrieves nylon for its Econyl factory in Slovenia. 
Credit: Aquafil

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