Influence of particle size of aggregates on the rheological behavior of crowded suspensions with silicone oils with different viscosities

Influência do tamanho das partículas dos agregados no comportamento reológico de suspensões concentradas com óleos de silicone de diferentes viscosidades

ABSTRACT

Two different sizes of aggregates of glass microspheres were compared in suspension with silicone oils of different viscosities. The concentration of the suspension was kept constant and equal to 62 vv.%. The rheological behavior of the suspensions was evaluated by the squeeze flow test, for two test speeds. For both particles size, when immersed in less viscous silicone oil, the yield stress did not show a good correlation with the tests speeds. Meanwhile, the more viscous silicone oil led to a good correlation between the yield stress and tests speeds. For the finer granulometry, the “viscosity” of suspensions increases with increasing viscosity of silicone oils and test speeds. But for the coarser granulometry, the “viscosity” of suspensions increases with the test speeds, and decreases as the viscosity of the silicone oils increases. These differences in the rheological behavior are closely related to the occurrence of non-homogenous flow, which depends on the relation between the percolation speed of silicone oils and the test speeds of the squeeze flow test. Thus, the size of particles influences in different ways the rheological behavior of these suspensions of glass microspheres. Consequently, a combination of the matrix phase viscosity and granulometry of aggregates phase can lead to a homogeneous flow.

Keywords
glass microspheres; squeeze flow; silicone oils; percolation