Abstract

In the present study, the dissolution of softwood fibers and fabrication of all-cellulose composites was investigated using aqueous tetraethylammonium hydroxide solution (TEAOH, 35 wt%) at room temperature. The bulk of the cellulose fibers were instantly dissolved when mixed with the solvent, and suspensions up to 3 wt% were fabricated with ease. During the dissolution, a few remaining larger fiber flocks were fully dissolved within 3 h of mixing at room temperature. TEAOH was further studied in the production of all-cellulose composites by solvent welding (partial dissolution) of cellulose fiber sheets. Tensile strength of the original cellulose sheet increased from 3.3 to 55.0 MPa only after 30 s of room-temperature solvent welding, and an increase of over 23-fold (up to 76.7 MPa) was obtained by high-pressure-aided hot-pressing of the partially dissolved sheets before drying. The demonstrated fabrication of all-cellulose composites yielded many benefits in comparison to the current dissolution systems, such as short treatment time, ambient operation conditions, and readily applicable processing solutions, which makes it a potential methodology applicable even at an industrial scale.