TEMPO-Mediated Oxidation of Norway Spruce and Eucalyptus Pulps: Preparation and Characterization of Nanofibers and Nanofiber Dispersions

摘要

This study deals with 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO)-mediated oxidation of cellulose. Softwood and hardwood pulp fibers were suspended in water and oxidized to various extents at pH 10 and 22 ℃ using sodium hypochlorite in the presence of TEMPO radical and sodium bromide. This reaction system is known to be the most efficient one for the introduction of both surface carboxyl and aldehyde groups. Important relationships between formation of these functional groups and the fibrillation yield, light transmittance of the water dispersions and degree of polymerization of the oxidized softwood and hardwood pulps were established in the present study. A birefringence test confirmed the presence of nanofibers which according to atomic force microscopy analyses had diameters in the 1.6-3.8 nm range.