Time‐dependent shear flow of artificial slurries in coaxial cylinder viscometer with a wide gap

Abstract

Abstract An experimental method was developed for characterizing time‐dependent slurries of elongated particles in a coaxial cylinder viscometer which has a wide gap between the inner rotating cylinder and the stationary cup. A model slurry system was studied; it consisted of a dispersed phase of regularly sized nylon fibres and a dispersing medium of an aqueous solution of polyethylene glycol with dextrose and sodium chloride, each of whose effects on the time‐dependent nature of the slurry could be examined. It was found that only a part of the gap between the cylinders of the viscometer flows under shear, and that the thickness of the flowing layer increases with time and approaches an equilibrium value. An empirical reaction‐rate type model was constructed for the time‐variation of the thickness of the flowing layer. A second order‐zero order reversible reaction model fitted the experimental data well. The fitting parameters of the model were correlated with slurry variables.