AbstractUsing a theory based on a modified Stokes' law equation, the settling behavior of fillers was investigated (glass beads and silica powder) in thermosetting epoxy casting resins during cure. In this study a suspension (a thermosetting epoxy casting resin) containing a large amount of filler particles is assumed to be a homogeneous fluid, and the settling phenomena are treated such that one or more particles of the filler settle into the homogeneous fluid under gravity without interference from other particles. The viscosity increase of the fluid during cure is taken into consideration. The experimental results agree well with the theoretical predictions when the settling distances are small and the particle size distribution is narrow. When these conditions are not satisfied, various effects are observed such as convection, filtering, combination, bottom effect, and a broad particle size distribution. In addition, the formation of a compression zone and of a compaction zone are clearly observed.
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