Viscosity of Unimodal and Bimodal Alumina/Epoxy Mixtures

Abstract

Experimental results on characteristics of viscosity η of unimodal and bimodal alumina/epoxy mixtures are shown and discussed based on theoretical consideration. Spherical alumina particles with nominal diameters of 35µm and 80µm, both of which had narrow dispersion of diameter distribution, were used as fine and coarse particles, respectively. η of the unimodal mixture increases remarkably with a volume packing fraction of particle ν p , and that Brinkman equation can be applied to estimate η from ν p . On the other hand, η of the bimodal mixture depends not only on ν p , but also on the ratio of coarse particles to fine ones. For larger ν p , η of the bimodal mixture becomes smaller than that of the unimodal mixture. It is shown that an approximation procedure of η yields reasonable estimation for smaller ν p , and underestimation for larger ν p .