Evaluation of the Physical Properties of Carboxymethylated Cellulose Nanofiber Derived from Red Algae Pulp

Abstract

This study investigated the utility of red algae bleached pulp (RaBP) as a raw material for producing carboxymethylated cellulose nanofiber (CM-CNF). Hardwood bleached kraft pulp (HwBKP) was used as control. Two types of carboxymethyl celluloses (CMCs) made from RaBP and HwBKP, respectively, were prepared according to the degree of carboxymethylation (CM), while considering the sodium hydroxide and chloroacetic acid dosage: low and high CM. Furthermore, the fiber morphology and charge density of the CMCs were evaluated to verify the carboxymethylation reaction. The final CM-CNFs produced from CMCs were ground for five passes using a microgrinder, and their fiber width, low-shear viscosity, and zeta-potential were analyzed.BRMorphology of CMCs revealed that the fibers were swollen and dissolved in water to produce transparent fibers. The charge density of the CMCs increased with increasing chemical dosage. When comparing CMCs according to species, the fiber size and charge density of CMC made from RaBP showed lower values than HwBKP. As the chemical dosage increased, fiber width and zeta-potential of CM-CNFs decreased, and their low-shear viscosity increased. The CM-CNFs made from RaBP had a lower fiber length and zeta-potential than those made from HwBKP. Therefore, RaBP can be potentially used to manufacture small and anionic CM-CNF by combining a carboxymethylation pretreatment and micro grinding.