Enhancing the Spinnability of Cellulose-Based Textile Waste by Doping with High Molecular Weight Bacterial Cellulose

Man-made cellulose fibers from well-managed forestry provide an eco-friendly alternative to polyester and cotton. The Ioncell process converts cellulose-based raw materials into high-quality textiles and offers strong potential for upcycling cellulose-based textile waste. Recycling discarded textiles is challenging because washing and abrasion degrade synthetic and natural fibers, reducing molecular weight and processability. Here, we demonstrate that adding a very small fraction of ultrahigh molecular weight bacterial cellulose enhances the spinnability of textile waste streams dominated by short-chain cellulose. This high molecular weight dopant systematically increases solution extensibility, stabilizing the extension-dominated fiber-spinning process. Viscoelastic stresses in a stable spinline scale with steady extensional viscosity at high strain rates and depend sensitively on chain extensibility. We quantify the enhanced tensile stress differences using capillarity-driven extensional rheometry combined with transient exponential shear rheometry to develop a <i>spinnability</i> metric for cellulose/ionic liquid solutions. These findings advance strategies for efficient recycling of postconsumer cellulose textiles.