Rheological Properties of Disperse Systems of Spherical Particles in Polystyrene Solution at Long Time-Scales. (III)

Abstract

The dynamic and steady-flow properties of disperse systems of spherical particles of styrene-methyl methacrylate copolymer crosslinked by divinyl benzene in a polystyrene solution have been measured at long time-scale regions by means of a cone-and-plate type rheometer. The diameter of particles employed in the study was very uniform and found to be approximately 120 mμ. Four kinds of particles having different contents of methyl methacrylate (MMA) and ζ-potential were dispersed in a polystyrene solution at a content of about 10%. The rheological behavior observed for these different systems depend strongly not only upon the MMA content but also upon the ζ-potential. However, MMA content and ζ-potential are not deter-mining factors individually.Depending on the relative magnitude of attractive and repulsive forces between dispersed particles, the dispersion state can be classified into three different groups. When the methyl methacrylate content in the particles and the ζ-potential of electric double layer on the particle surface are assumed as the respective measure of the attractive and repulsive forces, the rheological behavior observed for the four different disperse systems can be explained without contradiction.