Particle size and porosity measurements of cellulose nanofibers in slurries using centrifugal sedimentation

Abstract

The dispersion of cellulose nanofibers (CNFs) in liquids is a crucial process in the fabrication of advanced CNF-based materials. However, there has been limited research into the quantitative evaluation of dispersed CNFs. This study presents two methods for estimating the size and porosity of fibrillated CNFs in slurries. The first method is the line-start centrifugal sedimentation method that uses a density gradient under multiple centrifugal forces. The second method is the combination of the homogenous centrifugal sedimentation method with bulk density measurements. The estimated sizes and porosities of two fibrillated CNFs are consistent between the two methods, and the obtained sizes match well with the results of the polarized optical microscope (POM) image analyses. Quantitative analysis of the dispersion states of CNFs in slurries can help investigate their correlation with the function of CNF-based products and reveal the underlying mechanism.