Galina Rodionovaa, Tsuguyuki Saitob, Marianne Lenesc, Øyvind Eriksenc, Øyvind Gregersena, R. Kuramaeb, Akira Isogaib.
a Department of Chemical Engineering,Norwegian University of Science and Technology, 7491 Trondheim, Norway
b Graduate School of Agricultural and Life Sciences,The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
c Paper and Fibre Research Institute, 7491 Trondheim.
This study deals with 2,2,6,6-tetramethylpiperidine-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 oC 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.