Effect of Process Parameters on Feasibility of Production of Cellulose Nanofiber Yarn by Wet Spinning

Cellulose nanofibers (CNFs) have been attracting attention as engineering materials because CNFs have high tensile properties in addition to their biodegradability and reproducibility. Many research works have been conducted to produce high-performance composite materials using CNFs. Alignment of CNFs in composite materials is critical for achieving higher mechanical performance, but it is challenging because CNFs have high flexibility. Wet spinning of CNFs is a technique to obtain a pure CNF yarn by injecting CNF hydrogel into a liquid like acetone, followed by drying. The high shear rate in the injection nozzle gives the orientation of CNFs along with the flow direction, resulting in an almost unidirectional alignment of CNFs in the yarn. In this study, the effect of the inner diameter of the injection nozzle and the CNF concentration of hydrogel on the feasibility of the production of CNF yarns was experimentally investigated. The results showed that a limited range of the inner diameter of the injection nozzle enabled us to produce CNF yarns, but it was possible to produce CNF yarns within a certain range of CNF concentrations.