Abstract:In the present work, a combined method involving oxidation and high-pressure homogenization was used to treat the autohydrolyzed BKP (bleached softwood kraft pulp) for preparing cellulose nanofibril(CNF). Under alkaline condition, NaClO2 was used as an oxidant to decrease the zeta potential and the DP of the pulp. The oxidation time, temperature, NaClO2 dosage, as well as the pulp consistency were optimized, the zeta potential of the oxidized pulp, and the consumption of NaClO2 were determined. The results showed that the zeta potential of the oxidized pulp was obviously decreased, and the optimum conditions of oxidation were as follows: pulp consistency 10%, NaClO2 dosage 8%, oxidation time 6 h, and oxidation temperature 95℃. Under that optimized conditions, the zeta potential of the oxidized pulp was -37.6 mV, with a decrease of 43% compairing to the autohydorlyzed pulp. The oxidized pulp was treated using high-pressure homogenization to obtain CNF, and the dimension, viscosity, TG as well as the zeta potential of the CNF were analyzed. The results showed that the CNF with a good size distribution was prepared when the oxidized pulp was homogenized under 80 MPa for 70 times. The diameter distribution of the CNF was mainly in the range of 20~60 nm, and its length-to-diameter ratio was over 100. The zeta potential of the CNF was as low as -42.3 mV, indicating that the CNF had a good dispersion stability in aqueous medium. |