Characterization of cellulose nanofiber sheets from different refining processes

Four types of kenaf bast fibers were prepared via a combination of Wise treatments, for delignification, and alkaline treatments, for the removal of hemicellulose. Each type of kenaf bast fiber with different refining processes were nano fibrillated by grinding. Resulting, cellulose nanofiber (CNF) sheet was obtained from CNF by vacuum filtration (Scheme 1). The structures and properties of these CNF sheets then were investigated to determine how the CNF components had affected these properties. All of the CNFs from different refining processes were classified as a cellulose I-beta type by X-ray diffraction. However, the mechanical properties (Young's modulus, tensile strength and toughness) of the CNF sheet with Wise treatment were higher than the properties of the other three CNF sheets. These results strongly suggested that alkaline treatment was unnecessary for the removal of hemicellulose, and that the application of the Wise treatment effectively imparted high mechanical properties to the cellulose microfiber.