Although present in much of the clothing we wear on a daily basis, elastane is incredibly difficult to recycle. Researchers at the Vienna University of Technology (TU Wien) have uncovered a novel method to overcome these challenges, bringing the textile industry one step closer to its sustainability goals.
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Why Is Elastane Recycling Important?
Elastane, otherwise known as spandex or Lycra, can be found in tights, undergarments, and other clothing the world over. Derived from petroleum, the extraction and refining of this finite resource is a significant contributor to the textile industry’s carbon footprint.
Whilst the polyurethane basis for these products allows for the stretchy and comfortable products that we are used to, this synthetic polymer fiber complicates the textile recycling process to a significant degree, meaning that these petroleum-based products are often abandoned in landfills.
Beginning in 2025, used and waste textiles across Europe are to be recycled as per new, wider-encompassing measures put in place by the European Union. Uncovering new and more efficient means of coping with waste textiles is essential, especially when it comes to mixed fibers.
Why Is Elastane Difficult to Recycle?
Elastane is not only difficult to detect in textile recycling plants but also complicated to separate from other fibers without damaging them beyond repair. The stretchy nature of elastane causes issues in the recycling process, often clogging the typical machines used for textile shredding or appearing in small parts on other recycled fabrics.
The New Research
In a paper published in the journal Resources, Conservation and Recycling, researchers explored new means of both detecting and separating elastane in mixed fabrics. No effective and non-hazardous processes have previously been demonstrated in this regard.
Detection of Elastane
Concerning the detection of elastane in clothing, no previous methods have effectively, accurately, and quickly been able to identify the proportions of elastane in mixed fabrics.
In their new paper, the Tu Wien researchers outline how their new Elastane Quantification Tool (EQT) can identify how much elastane is present in a particular fabric. The researchers employed mid-infrared spectroscopy in their EQT in order to measure elastane levels effectively.
Effective Separation of Elastane
Thermal decomposition methods alter the entire textile matrix, while shredding textiles can create bothersome strings of elastane in machines due to its stretchy nature. Therefore, the researchers considered a new approach: a non-hazardous solvent to dissolve the elastane that rivals the effectiveness of hazardous solvents employed in previous research.
Six organic solvents were tested against one another in order to identify which was the most effective in dissolving elastane in mixed fabrics following effective identification. The researchers focused on polyester/elastane and polyamide/elastane textile waste when testing their solvents.
It was found that Dimethyl sulfoxide (DMSO) was the most effective solvent that is scalable and environmentally friendly. They also identified that under current REACH regulations, it is not listed as having any classified hazards. Ultimate treatment temperatures were found to be 120 degrees Celsius in order to dissolve elastane in just ten minutes.
Using DMSO, the researchers were able to recover not only elastane but the polyester and polyamide fibers for textile recycling and regeneration. Further, the DMSO itself could be recovered for further separations.
Analytical Testing
To guarantee their results, the scientists used a series of analytical methods for material characterization. This included scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy.
This allowed them to test the ideal parameters of their method, including temperature and dissolution time, as well as to verify the quality of the recovered fibers. The SEM analysis showed that there were no visible changes to the recovered fibers following treatment.
Next Steps
The impacts of these new findings could be immense. The effective separation of elastane from mixed textiles without using environmentally- and human-hazardous solvents could allow for the recycling of exponentially more materials, bringing us closer to a circular textile industry and making sustainability legislation that much easier to implement.
A patent has been filed for this method, and the next step for the research will be to scale the process up to an industrial level.
References and Further Reading
Elastane recycling: Stretching the lifespan of textiles (2023) Elastane recycling: Stretching the lifespan of textiles | TU Wien. Available at: https://www.tuwien.at/en/tu-wien/news/news/elastan-recycling-dehnbare-lebensdauer-fuer-textilien (Accessed: 13 December 2023).
Emanuel Boschmeier a et al. (2023) New separation process for elastane from polyester/Elastane and polyamide/Elastane Textile Waste, Resources, Conservation and Recycling. Available at: https://www.sciencedirect.com/science/article/pii/S092134492300349X?via%3Dihub (Accessed: 13 December 2023).
Researchers find way to remove the scourge of textile recycling: Elastane (no date) texfash.com. Available at: https://texfash.com/update/researchers-find-way-to-remove-the-scourge-of-textile-recycling-elastane (Accessed: 13 December 2023).
Other synthetics. Textile Exchange. (2023, January 3). https://textileexchange.org/other-synthetics/