Effect of Polyelectrolyte-Cationized Cellulose Nanofibril on the Properties of Paper

Abstract

In this study, the effect of a cationic cellulose nanofibril (CNF), produced by combining surface-modification using cationic polyelectrolyte and micro-grinding, on the strength of paper, was evaluated. Hardwood bleached kraft pulp (HwBKP) was pretreated with poly-DADMAC, and then a method of previous study was conducted, followed by micro-grinding. Afterward, the zeta-potential and fiber width of the untreated and cationic CNFs were measured. The handsheets were produced by adding the untreated and cationic CNFs into the furnish that was prepared with HwBKP and softwood BKP (SwBKP), after which their physical properties were evaluated. The drainage rate and chemical oxygen demand (COD) of the furnish were analyzed based on the addition of CNFs to identify the effect of cationic CNF on the drainage and retention at the wet-end part.<BR>Further, the zeta-potential of the cationic CNF surface-modified with poly-DADMAC exhibited a positive value, but no significant difference was noted in the fiber widths based on the surface-modification. The cationic CNF exhibited higher tensile and burst indexes, and folding endurance because of higher retention at the wet-end part and higher fiber bonds than that in the untreated CNF. However, the cationic CNF did not show the difference in the ISO brightness and opacity of the paper, and the drainage rate of the furnish from untreated CNF. Thus, it was concluded that the cationic CNF, produced via surface-modification using poly-DADMAC and micro-grinding, was more effective in improving the strength of the paper regarding the similar optical properties of the paper, as well as the drainage rate of the furnish, compared with untreated CNF.