Viscoelastic properties of monodisperse spherical silica suspension

The viscoelastic properties of the suspension of monodisperse spherical silica produced by hydrolysis of tetraethoxysilane in alcohol solvent with ammonia as a catalyst in polyethylene glycol (PEG) were studied. The results show that the SiO2/PEG suspension possesses the reversible shear thinning and shear thickening behaviors. In the shear thinning region, the loss modulus (G″) almost remains unchanged, whereas the storage modulus (G′) decreases. In the shear thickening region, G″ and G′ increase for the formation of the “clusters”. The larger G″ over G′ in all the stress studied shows that the system mainly possesses the viscous property, and that the energy dissipated(E d) is larger than that stored. E d of this suspension is proportional to the maximum strain (γ max) rising with the exponent of 1.92 under low shear stress; however, in the shear thickening region, E d is proportional to γ max rising with the exponent of 5.00.