This SBIR Phase I project aims to prove the technical feasibility and the economic viability of natural fiber welded and dyed yarns and fabrics. Natural fiber welding is process that swells and mobilizes polymers within natural fibers to create higher performance yarns and fabrics. At sufficiently fast rates, individual fibers are fused and bonded together without glues or resins while retaining a majority of the natural structure and order of natural polymers. This leads to improved mechanical properties while maintaining the benefits of a natural product. Moreover, during the welding process, functional materials and chemistries including dyes, antimicrobials, and flame retardants can be simultaneously locked within yarns and fabrics in new eco-friendly ways. This new ability has potential to displace, for example, present day resource intensive processes such as indigo dyeing for denim which is a water and chemical intensive process that requires significant equipment investment. Inclusion of indigo dye via natural fiber welding processes has tremendous potential to reduce the environmental impact of denim manufacture while saving costs and simultaneously improving the performance of resultant fabrics and with innovative new design effects. This type of disruptive innovation would bring in sustainable US-based manufacturing throughout the value chain of the massive multitrillion dollar per year textile industry. An extremely promising and tunable class of solvents for natural fiber welding processes are called ionic liquids. This project explores several new types of ionic liquid-based solvent systems co-optimized with new automated hardware designs to cost effectively enact natural fiber welding processes with cotton and other natural fiber-containing yarn substrates. In so doing, ionic liquid-based process solvents are recovered in a closed-loop recycling process thereby enabling economic viability as well as creating an eco-friendly manufacturing platform. This project will focus on proving proof of concept with new combinations of ionic liquid(s) and co-solvent(s) to enable concurrent welding with indigo dyeing while developing high efficiency recycling methodologies. There are known methodologies to separate ionic liquids in dilute aqueous solutions but these have not yet been developed for situations where additional miscible co-solvents are present. The objective of this project is to demonstrate natural fiber welding processes that deliver indigo dye into cotton-based yarn substrates while achieving high rates of recycling with process solvents that contain co-solvent(s) and to enable scalable processes for potentially billions of pounds of denim products produced annually.
