Abstract
Viscoelastic properties of aqueous disperse system of clay-starch and calcium carbonate-starch, so-called coating colors, were studied in the frequency range 10-2-103 rad/sec using two types of rheometers. Flow properties were also measured using a coaxial cylinder rheometer. Coating colors having different average sizes and distributions were used.
In the low frequency region, values of G′ and G″ at small strains increase with decreasing particle diameter and become independent of frequency. The result suggests that the network structure, due to the aggregation of dispersed particles, becomes denser with decreasing size of dispersed particles.
Under steady shear flow, the yield values as well as the shear stresses at finite rates of shear increase with decreasing particle size. The phenomena may be explained in terms of the of fective volume of dispersed particles including the solvating phase, which is considered to depend mostly on the interaction between particles or strength of the interparticle bond.
In the disperse systems which consist of various sizes of dispersed particles, the discrepancy is observed between the viscoelastic properties for small sinusoidal deformation and those for steady shear flow at the corresponding time scale.
