Dyeability and heat–moisture comfort properties of weft-knitted fabrics with recycled polyurethane filament

In order to study the dyeability and the heat–moisture properties of recycled polyurethane filaments (PUF), a weft-knitted fabric containing recycled materials was developed. The recycled polyester (rPET) yarn was threaded as face yarn and recycled polyurethane filament (rPUF) as ground yarn in the plating stitch fabrics, compared with polyester (PET) and PUF. Four types of knitted fabrics were designed on S 296-2 single-sided knitting machines. The dyeability, air permeability, moisture permeability, and thermal resistance of the four samples were investigated. In addition, the tensile properties and drapability of fabrics were characterized. Results demonstrated that fabrics with recycled materials exhibited superior dyeability, breathability, and moisture permeability versus virgin counterparts. Notably, the dyeing performance was improved significantly under disperse dye dyeing, with the dyeability at 110°C exceeded virgin fabrics at 130°C by >10% ( p < 0.01), highlighting energy-saving potential. The air permeability of recycled fabrics with rPET and rPUF increased by 20% ( p < 0.05), and moisture permeability increased by 15% ( p < 0.05). These findings establish rPUF as a promising material for sustainable sportswear.