Viscosity of Concentrated Colloidal Solutions of Magnetite

摘要

For magnetite colloidal solutions in kerosene stabilized by oleic acid, concentration and temperature dependences of viscosity are determined at parameters varied over wide ranges. The concentration dependence of viscosity is satisfactorily described by the Chong equation (modified to some extent), while the discrepancy between the temperature dependence and the theoretical data can be as large as two orders of magnitude. The observed discrepancy is explained by a decrease in the thickness of the shells composed of surfactant molecules on the particle surface with temperature. At extremely low concentrations, the increment to the effective viscosity linear with respect to concentration is slightly (by 14%) larger than the Einstein value, which may be due to the presence of a small number of aggregates in the solutions.