The selective chemical-recycling process operates at 80°C and leaves more than 96% of companion cotton and elastane intact, addressing one of the toughest barriers to recycling stretch blended textiles.
Researchers led by Donghua University in Shanghai have developed a chemical recycling process capable of selectively breaking down polyester in blended textiles while preserving more than 96% of accompanying cotton and spandex fibres.
Published in the Journal of Hazardous Materials, the method achieves complete PET conversion in 80 minutes at 80°C, recovering terephthalic acid (TPA) at 99% purity and a 99% monomer recovery rate.
Selectivity tackles the elastane problem
Polyester–spandex fabrics are particularly difficult to recycle because elastane is intimately blended with PET and can be damaged during conventional chemical depolymerisation.
The Donghua team uses a sulfolane/ethylene glycol-potassium hydroxide co-solvent system. Sulfolane alters hydrogen-bond interactions at the solvent-polymer interface and swells the PET structure, allowing ester bonds in polyester to be attacked selectively while largely preserving the chemically different structures of cellulose and spandex.
That distinction matters for activewear, sportswear, underwear and stretch denim, where even relatively small elastane contents can complicate recycling.
Multiple materials can be recovered
The process was successfully tested on PET/cotton and PET/spandex fabrics, as well as polyester foams and other polymers including PLA, PBAT and PBT.
Researchers also demonstrated in-situ dye extraction and repeated solvent reuse, potentially allowing colourants and non-polyester fibres to be recovered rather than sacrificed during polyester recycling.
From mixed waste to separate feedstocks
The advance shifts the objective from simply recycling PET to selectively recovering every useful component of a blended textile. High-purity TPA can potentially return to polyester production, while intact cotton and spandex could enter separate recovery pathways.
The remaining challenge is industrial economics. Commercial relevance will depend on solvent recovery efficiency, chemical consumption, wastewater generation, energy requirements, throughput and fibre quality after repeated processing.
If those metrics scale favourably, selective depolymerisation could remove one of the main technical obstacles preventing polyester-rich stretch garments from entering genuine textile-to-textile recycling systems.
