THE NANO-CELLULOSE FIBER PREPARATION BY TEMPO-MEDIATED OXIDATION WITH ULTRASOUND

One-step process to obtain cellulose fibrils from the solution directly without any post-treatment was developed through oxidizing cotton linter by the TEMPO-NaBr-NaClO system at the ultrasonic condition of 40kHz for 13.5 hours. C6 primary hydroxyl groups on the surface of cellulose fibrils were converted to carboxyl groups during cellulose fibrils liberated from the fibers. The amount of carboxyl group could go up to 1.66 mmol/g. During the oxidization process, the crystallinity of cellulose fibrils decreased gradually with the reaction time. Transmission electron microscopic observation showed that individualized cellulose fibrils were 5-10 nm in width and 200-400 nm in length. Individualized cellulose fibrils stabilized by surface charge were well-dispersed in aqueous solution.