Facile and Quantitative Method for Estimating the Isolation Degree of Cellulose Nanocrystals (CNCs) Suspensions

The isolation degree of cellulose nanocrystals (CNCs) suspensions calculated from the amount of sediments obtained with the centrifugation method can be estimated with turbidimetry, surface charge and dispersion analysis of the CNCs suspension. Three different types of raw cellulosic materials were used and carried out with an acid hydrolysis and mechanical disintegration. As the number of high-pressure homogenizer treatments increased, the isolation degree of CNCs from microcrystalline cellulose (MCC) increased from 2.3 to 99.6%, while the absorbencies from turbidimetric measurement of the CNCs suspension decreased, from 2.6 to 0.1 Abs units. Furthermore, the surface charges based on zeta potential measurements of the CNCs suspensions increased from −34.6 to −98.7 mV, but the heights of sediments from the CNCs suspensions were reduced, from 4.01 to 0.07 mm. Similar results were obtained for CNCs from softwood pulp (SWP) and cotton pulp (CP). These results show a direct correlation between yield, turbidity, surface charge and sedimentation of CNCs suspensions. Their correlation indices (0.9) were close to a maximal value of 1. This approach can be suggested as a facile and rapid estimation method for CNCs manufacturing process.