A theoretical model to investigate the performance of cellulose yarns constrained to lie on a moving solid cylinder

Cellulose fibers, such as cotton and linen, are abundant in farmer’s fields. The traditional bottom-up technology to process these short staple fibers is spinning. State-of-the-art spinning technology requires not only high throughput processing of the cellulose fibers, but also the addition of functionalities and value into the supply chain. Recently, a modified ring spinning system has been developed which introduces a false twist into a traditional ring spinning frame. The modified system produces cellulose yarns that have a high strength but low twist, and a soft hand similar to cashmere. Unlike traditional textile finishing treatments which consume plenty of chemicals, water, and energy, this method is purely physical and sustainable. The superior properties of the modified cellulose yarns are attributed to the modified yarn morphology and structure. Theoretical investigation is, therefore, important in understanding of the spinning mechanisms of the modified ring spinning process that changes the morphology and structure of the cellulose yarns. In this paper, yarn behavior constrained to lie on a moving solid cylinder was theoretically and experimentally investigated. Equations of motion were derived based on the Cosserat theory and numerical solutions in steady-state were obtained in terms of yarn spatial path, yarn tension, twist distribution, yarn bending, and torsional moments. Effects of various spinning parameters including wrap angle, speed of the moving cylinder, yarn diameter, yarn tension, yarn twist, and frictional coefficient, on yarn behavior were discussed. The results suggested that in most cases the bending and torsional moments are of the same order of magnitude, and thus the effect of bending cannot be neglected. Experiments in the modified ring spinning system were conducted to verify the theoretical work, and good agreement has been made. Some simulation results of this study were compared with the results of earlier models as well as with experimental data, and it was found that the current model can obtain a more accurate prediction than previous models in terms of yarn twist and tension. The results gained from this study will enrich our understanding of the spinning mechanism of the modified ring spinning process and better handle of cellulose fibers for functional and value-added applications.