Abstract
Viscosities of γ-Fe2O3 dispersions in epoxy resin, phenol resin, and polyvinyl butyral solutions are measured at shear rate D from 19.2 to 384 sec−1. Volume fraction of γ-Fe2O3 in these dispersions ranges from about 0.002 to 0.03. The concentration dependence of relative viscosity η/ηs is closely represented by the Mooney equation. From this equation, intrinsic viscosity [η] of suspensions is found to decrease from 46.1 at D = 19.2sec−1 to 14 at D = 384 sec−1 for epoxy resin solution. The high [η] value indicates the existence of flocs containing immobilized liquid. By increasing the shear rate, the average floc size is reduced to point where at an infinite shear rate, only small clusters or possibly particles remain. Of the three polymers, the lowest [η] value is obtained in the dispersion of the phenol resin solution.
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