Mechanical textile recycling efficiency: Sample configuration, treatment effects and fibre opening assessment

• Raising and sandpaper treatments simulate wear for textile recycling efficiency. • Raising and Afilan treatment reduces fibre length loss during recycling. • Feed direction is a critical factor for fibre length retention. • Thread system used for feed guide in recycling is the main content of opened fibres. • New air flow permeability test effectively measures fibre opening degree. The mechanical textile recycling process significantly reduces fibre length. Previously, we explored how lubricant pre-treatment before mechanical recycling reduced the fibre length loss. In this study, we added simulated wear to assess its influence on the fibre length output. We also evaluated the influence of sample shape and feed direction on recycling efficiency. We treated plain woven cotton textiles were subjected to either sandpaper grinding or steel needle raising. Finishing treatments with polyethylene glycol 4000 and Afilan CFA 100 were also used in combination. Samples were prepared in two shapes and fed into the recycling machine with warp threads oriented longitudinally, perpendicularly, or diagonally. Recycling efficiency was evaluated based on fibre length and the degree of fibre opening using a novel air flow permeability test. The results showed that sandpaper treatment degraded fibres, while the raising treatment improved recycling efficiency. A previously unreported finding was that the size, shape and feeding direction of woven fabrics showed significant effects on the fibre length output. Material fed with a thread system aligned longitudinally to the recycling machine direction resulted in a higher proportion of opened fibres and fewer unopened fabric pieces. It was further observed that the yarns aligned longitudinally with the feed direction exhibited significant opening, while those oriented perpendicularly remained largely unopened. The new method for measuring the degree of opened fibres proved effective and holds promise for future application. These findings provide tangible guidance on the mechanical recycling protocol and means to improve output assessment procedures.