Rheo-optic measurements on dilute suspensions of hematite rods

Abstract

The microstructural changes induced by shear in dilute suspensions of colloidal Fe2O3 rods (aspect ratio = 8.4) have been studied using a novel rheo-optic technique. The large extinction coefficient for the hematite system at the wavelength used (λ = 392 nm) enables rheo-optic experiments on truly dilute suspensions to be undertaken. The elimination of any particle-particle interactions ensures that the measurements obtained can be directly related to the induced physical changes of the isolated particles. Optical absorbance spectra have been measured over a range of shear rates and angle of light polarization relative to the shear direction. The measured absorbance changes can be directly a..