The effect of the shape of micron-sized particles on the rheological behavior of their concentrated suspensions

Particle shape is one of the most important and fundamental factors on the rheological behavior of filled suspensions. In this study, for the first time, the effect of three different shapes of particles on the rheological behavior of concentrated suspensions in three forms of spherical, elliptical paraboloid and boat-like (based on acrylic resin) was studied. Spherical particles were prepared by suspension photo polymerization and non-spherical particles were fabricated by three-dimensional printing (DLP), followed by being dispersed in a silicon oil substrate. Flow curves of the obtained suspensions at different concentrations for all three shapes confirm that the samples show a shear thickening behavior with increasing shear rate. The maximum packing volume fraction for each suspension was fitted using the Krieger-Dorty model with the least squares method. This value is the maximum for the spherical shape and decreases in non-spherical shapes with increasing aspect ratio. The hysteresis loops in the flow curves increase with increasing volume fraction, and then collapse near the maximum packing fraction.