濃厚分散系の流動学的性質

Abstract

Using an electrically-recording rotational rheometer, the rheological properties of suspensions of barium sulfate in nonpolar polyisobutylene were measured and compared with those of suspensions in polar linseed oil (thermally polymerized). Measurements of the flow properties at low rate of shear and of the dynamic viscosity and the dynamic modulus were made in the range of very low frequencies.In the former suspensions, with increase of concentration of barium sulfate, the yield value in steady-state flow and the dynamic viscosity and the dynamic modulus become larger, and the frequency-dispersion curve shifts to the lower frequency side. On the other hand, in the latter suspensions concentration dependence of those properties was not so significant.A minute addition of water to the former suspension increase the yield value and also the dynamic viscosity and the dynamic modolus. In the latter suspensions, there are almost no changes in the rheological properties on addition of water.Adsorption of sodium stearate on particles of barium sulfate gives reverse effects on the rheological properties.Anomalous plastic and anti-thixotropic behaviours were observed in the flow properties of the former suspensions.In concentrated suspensions, inter-particle interactions should be considered. A minute amount of substance adsorbed on the surface of particles may induce the coagulation of particles and build up a kind of structure in the system.