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Suspensions composed with silica particles or cellulose fibers dispersed in glycerin and/or xanthan aqueous solutions were formulated with solids volume fraction varying up to 15 and 10 % for silica and cellulose dispersions, respectively. In addition, xanthan was added to the aqueous solutions (water or 82 % glycerin + water) at concentrations of 0.005, 0.1, and 0.2 % to impart non-Newtonian character to matrices, and results were compared to the Newtonian systems, without xanthan addition. Even though developed for suspensions in Newtonian fluids, Krieger-Dougherty and Eilers models described properly the influence of solids content on the flow behavior of suspensions in non-Newtonian fluids. Generally, increasing cellulose particles concentration led to an increase on the suspension pseudoplasticity, while for silica particles such increase was more discrete. Low deformation rheological measurements showed that glycerin-containing matrices were more independent on frequency as compared to suspensions of aqueous xanthan solutions. Results showed that, besides particles characteristics, the rheological properties of the suspending matrix are crucial for determining the arragements and flow properties of suspensions. |
