Scientists Find Potential Solution to Spandex Recycling Problem
Scientists in Vienna have developed a feasible and up-scalable process for separating elastane, also known as spandex, from textile waste, the first of its kind ever formulated.
Working with six different organic solvents, the chemists at the Vienna University of Technology settled on non-hazardous dimethyl sulfoxide (DMSO) as the best. Experiments were conducted on polyester/elastane and polyamide/elastane textile waste samples, on which the DMSO was shown to be the most favorable and which also runs circular within a three-step purification.
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Principle component analysis (PCA) of spectroscopic measurements (ATR-FTIR) showed excellent results for the polyester and polyamide components which were fully recovered. The experiments concluded that such complete recovery and simultaneous purification of the solvent used for elastane separation in a closed loop is possible.
Elastane is a synthetic polymer fiber based on polyurethane, which increases the flexibility and comfort of garments but which causes a great number of problems in textile waste recycling. To date there has been no scalable process to tackle the problem of separating elastane from other textiles in a blended cloth that allows the host fibers to be recycled. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) on textile samples were proof of the success of the developed process.
The growth of the world’s population and the expansion of fiber production has caused per capita consumption of those fibers to increase to 14 million metric tons in 2022, from 8.4 million metric tons in 1975, according to the United Nations (2023). Predictions say it will hit 17.5 million metric tons per capita by 2030, according to the Textile Exchange in 2022. While cotton production has stagnated over the past two decades, the production of synthetic fibers has grown by 5.5 percent per year since 1970 which means that by 2021 the total of synthetic fibers (polyester, polyamide, elastane and others) already accounted for 64 percent of the entire fiber market.
The European Union targeted textiles in 2018 with the Waste Framework Directive and in 2022 it underscored the importance of textile waste management with the adoption of Textile Strategy. Currently fiber-to-fiber textile recycling is non-existent, although it is increasingly acknowledged as critical to creating a circular economy in the textile sector to protect the environment.
Few studies have investigated the separation of elastane fibers from textile waste and none has been successful until now. There have been experiments using the hazardous organic solvent N,N-Dimethylformamide (DMF) and it is a good solvent, but under Registration, Evaluation and Authorization of Chemicals (REACH) it is highly restricted.
Other experiments have involved degrading elastane in fabric blends and washing them with ethanol, taking cotton blends and dissolving the cotton while leaving the elastane, treating textiles with solvents and tetrahydrofurfuryl alcohol (THFA) but it is unsafe to female fertility or unborn fetuses. Successful experiments like that with DMSO could be key in moving the textile industry from a linear economy to a circular one.
