Influence of the elasticity of cellulose solutions on the dispersion of carbon black agglomerates
Résumé
A counter-rotating rheo-optical tool was used to study the dispersion process of carbon black agglomerates in different suspending media, including the solutions of different types of cellulose, aqueous hydroxypropylcellulose solutions, and polyisobutylene. For each suspending fluid, the mechanism of dispersion (erosion or rupture) was identified, and the macroscopic critical shear stress necessary for dispersion was measured. Checking that the impacts of fluid infiltration and agglomerate size on the macroscopic critical shear stress for dispersion were negligible in our case, we showed that elasticity is a major factor acting on dispersion physics. At a constant viscosity, the higher the elasticity is, the more difficult dispersion is, giving higher critical shear stresses for initiating dispersion. There is a linear correlation between the suspending fluid elasticity and this critical shear stress, independent of temperature. An explication of the influence of matrix elasticity on agglomerate dispersion based on recent numerical simulation is given.