Rheology of Suspensions and impact of Cellulose Nanocrystal as an additive

Abstract

Suspensions, as complex fluids, embody a fascinating interplay of solid particles within a liquid medium, presenting a diverse range of viscosity behaviors. Unlike simple Newtonian fluids, suspensions exhibit non-linear responses to applied forces, owing to interactions between dispersed particles and the surrounding solvent. Their viscosity can vary significantly with factors such as shape and size of particle, surface chemistry and concentration. Understanding the rheological properties of suspensions is crucial across industries like pharmaceuticals, cosmetics, paints, and food processing, where their flow behavior dictates product quality and performance.

The research examines the consistent rheological characteristics of suspensions containing solid particles thickened by cellulose nanocrystals. Two distinct types and sizes of particles are utilized in preparing the suspensions: TG hollow spheres with a Sauter mean diameter of 69 µm and Solospheres S-32 with a Sauter mean diameter of 14 µm. The concentration of nanocrystals ranges from 0 to 3.5 wt%, while the particle concentration varies from 0 to 57.2 vol%. Additionally, the study investigates the impact of salt (NaCl) concentration upto 2 wt% and pH varying from 3 to 11 on suspension rheology. Generally, the suspensions display shear-thinning behavior, with a more pronounced effect observed in suspensions containing smaller particles. Experimental viscosity data conform well to a power-law model, with variations in flow behavior index and consistency index and under different conditions being thoroughly examined and discussed.