Although there has been some research on how to use short fibers from mechanically recycled textiles, little is known about how to preserve the length of recycled fibers, and thus maintain their properties. The aim of this study is to investigate whether a pre-treatment with lubricant could mitigate fiber length reduction from tearing. This could facilitate the spinning of a 100% recycled yarn. Additionally, this study set out to develop a new test method to assess the effect of lubricant loading. Inter-fiber cohesion was measured in a tensile tester on carded fiber webs. We used polyethylene glycol (PEG) 4000 aqueous solution as a lubricant to treat fibers and woven fabrics of cotton, polyester (PES), and cotton/polyester. Measurements of fiber length and percentage of unopened material showed the harshness and efficiency of the tearing process. Treatment with PEG 4000 decreased inter-fiber cohesion, reduced fiber length loss, and facilitated a more efficient tearing process, especially for PES. The study showed that treating fabric with PEG enabled rotor spinning of 100% recycled fibers. The inter-fiber cohesion test method suggested appropriate lubricant loadings, which were shown to mitigate tearing harshness and facilitate fabric disintegration in recycling.

Several qualities influence the processability of textile staple fibers: inter-fiber cohesion being one of the most important properties. Although various methods to measure this property have been explored, there is no consensus on the optimal technique, and existing methods often require specialized machinery. This article introduces and evaluates a straightforward method that utilizes only a carding machine and a tensile tester, both standard equipment in yarn laboratories. The proposed cohesion test method involves preparing carded webs, cutting them into nine rectangles, and then subjecting these samples to tensile testing . The method was initially assessed for repeatability and the normalization of results. Further experiments varied the fiber material (cotton and polyester), fiber organization, direction of fiber hooks, and finishing treatments. Force curves and their gradients were analyzed, alongside video footage, to study inter-fiber interactions during testing. The results demonstrated that the new test method could differentiate between fiber materials, fiber organizations, and quantify the effects from finishing treatments. The cohesion force (CF) of CO fibers was 30 % of that of PES fibers; carding had a greater impact on CO fibers compared to PES fibers, and treatment with lubricant reduced the CF by up to 35 %. However, the weight and dimensions of the samples must be controlled to ensure repeatability. In conclusion, the developed inter-fiber cohesion test method offers a promising and accessible approach to analyzing inter-fiber interactions in staple fibers.