Study on Cellulose Nanofiber Molding by 3D Printing

Cellulose nanofibers (CNF) are obtained by finely unraveling fibers extracted from plants like wood, into nano-sized elements. CNF is lightweight yet has high strength and little thermal expansion. It is known to be five times lighter than steel but more than five times stronger. With the conventional method, it takes a long time to manufacture a molded product from CNF as it requires a long filtration step of the CNF aqueous suspension, which is an obstacle to fabrication. In this experiment, we propose to establish a new molding process with the aim of shortening the time required to manufacture molded products. Specifically, it is a method of connecting a home-made syringe pump to a commercial 3D printer to directly print the CNF suspension into shape. By adopting this method, filtration can be omitted from the conventional molding process. A concentrated CNF suspension is used as the feeding material for the 3D printer, and the syringe pump enables the extrusion of CNF hydrogel into the 3D printer. As CNF suspension has high thixotropic properties, it is expected that shear-thinning allows proper extrusion through the narrow channels. Experiments were conducted with the aim of establishing a method for accelerating the production of CNF-molded products.