Sustainable and cleaner production of elastic core-spun yarns for stretch denim with maximal utilization of recycled cotton extracted from pre-consumer fabric waste.

Stretch denim is an exclusive and stylish textile made with elastic core-spun yarns. It has gained substantial traction for offering essential elasticity and resilience to the garments while retaining a snug fit and comfort when worn. Denim is produced from coarser cotton yarns necessitating a significant quantity of cotton fiber. Owing to the escalating costs of cotton and the harmful environmental impacts associated with its cultivation, it is imperative to explore alternative fibers for denim. Herein, for the very first time, an expedient technique of manufacturing elastic core-spun denim yarns utilizing recycled cotton is investigated. Recycled cotton fibers, in the range of 10-60 %, extracted from pre-consumer fabric waste were blended with virgin cotton and spun into 16 Ne (36.9 Tex) elastic core-spun yarns. To address the challenges posed by the lower spinnability of recycled fibers, attributed to lower fiber length, uniformity index, and higher short fiber content, a compact spinning system featuring a novel pin spacer was used. This combination effectively improved the fiber control within the drafting zone, enabling maximum incorporation of recycled cotton, up to 60 %, into the yarn. The produced yarns exhibited significantly lower unevenness, imperfections, and hairiness along with higher strength and elongation that fell within the top 5 %-50 % ranking of Uster Statistics 2023. The elastic core yarn, even containing 60 % recycled fiber, demonstrated its suitability for use as a weft yarn in a commercial high-speed air-jet loom operating at 950 rpm (equivalent to weft speed 94 km/h or 1577 m/min). The production of denim yarn incorporating 60 % recycled cotton represents an innovative concept to advance sustainable development goal (SDG) 12. This initiative aims to reduce the proportional demand for cotton cultivation and its subsequent processing, thereby making significant contributions to environmental preservation on various fronts. Moreover, this approach offers potential cost savings in the production of denim clothing.