Chemical degradation and Upcycling of discarded polyester-spandex blended fabrics to high Tg transparent polyester

Textiles, as a fast-moving consumer goods (FMCG), are mass produced and used in modern daily life. Polyester-spandex blended fabrics, a major category of pure chemical fiber products, are primarily recycled through the mechanical recycling or chemical degradation, with a notable lack of research on upcycling. We propose a chemical degradation and upcycling pathway based on transesterification principles to prepare high-value transparent poly(ethylene terephthalate)-tricyclodecanedimetthanol (TCDDM) copolymer by discarded polyester-spandex blended fabrics. Employing a selective separation strategy, the spandex component of the polyester-spandex blended fabrics was separated with dimethylacetamide (DMAC) solvent. Then, the separated polyester fabric was chemical degradation with ethylene glycol (EG) solvent to obtain the bis(2-hydroxyethyl) terephthalate (BHET) monomer. The reaction was carried out at 190°C for 3h by setting up a reflux apparatus, This is milder reaction conditions and simpler setup than methanolysis. Finally, the upcycling of r-PETGs containing TCDDM was carried out via melt polycondensation. The r-PETGs possess higher T g of 85.6-115.4°C, and can be utilized in transparent application scenarios under high temperatures. Our work offers a pathway for degrading and upcycling textile waste by transforming it into high-value transparent materials, supporting chemical degradation and circular economy in the fiber industry.