The Use of Sedimentation for the Estimation of Aspect Ratios of Charged Cellulose Nanofibrils

In this study, the aspect ratios of carboxymethylated and TEMPO-oxidised cellulose nanofibrils (CNF) were estimated by gel point analysis using a sedimentation approach. The flocculation and subsequent sedimentation of the CNF aqueous suspensions, which were stabilised by negative repulsive forces, were made possible after screening in concentrated salt media. The aspect ratios of the CNFs were then calculated from the linear fit (gel point) of the plot of concentration of the CNFs against the relative sediment height, using the crowding number theory.