Analysis of the Influence of Silicon Dioxide Nanoparticles on the Rheology of Xanthan Gum Suspensions

The effect of silicon dioxide nanoparticles on the rheology of aqueous solutions of xanthan gum was studied. Tests were carried out on a rotational viscometer and by the oscillatory method on an Anton Paar rheometer. Additions of nanoparticles up to 2 wt.% to solutions containing up to 1 wt.% gum were analyzed. In the studied concentration ranges, the influence of nanoparticles maintains the shape of the flow curves and viscosity curves, introducing small changes. It was shown that with increasing concentration of nanoparticles, the elastic modulus of suspensions, the values of their yield strengths and flow points increase. At the same time, the pseudoplasticity index practically does not increase, leading to the manifestation of a brittle rupture with increasing load in the oscillatory test of the suspension. The storage modulus at a nanoparticle concentration of 1% takes on a two-stage form, and at a concentration of 2% it forms a hysteresis curve, indicating a brittle rupture of the material. It was shown that the effect of the conformational transition is about 30% and decreases with increasing flow shear rate.