Abstract
We investigate the effect of shear and electric field (E) on the rheology of fumed alumina (Al2O3) − in − silicone oil suspensions (Al2O3/silicone oil) at varying Al2O3 nanoparticle loadings of 0.5wt%–15wt%. 0.5wt% and 2.5wt% Al2O3/silicone oil suspensions behave as Newtonian fluids and form gel − like suspensions at a nanoparticle loading of 10wt% and above; attributed to the formation of a particulate network of fumed Al2O3 nanoparticles. Transient step − down experiments with 5wt% and 15wt% Al2O3/silicone oil suspensions indicate shear thinning and thixotropy. We also show that the dynamic rheology of gel − like 15wt% Al2O3/silicone oil suspensions is extremely sensitive to the preshearing protocols. Depending on the preshear, partial or complete breakdown of the network structure in 15wt% Al2O3/silicone oil suspensions is observed. Once the network structure breaks, the structural recovery doesn’t ensue at rest after the cessation of shear. On application of E, Al2O3/silicone oil suspensions with 0.5wt%–5wt% Al2O3 nanoparticle loading exhibit diverging low shear viscosity, frequency independent G′ along with the presence of a yield stress. The electrorheological response of 5wt% Al2O3/silicone oil suspensions is independent of the preshearing protocols at an applied E=1kV/mm. Furthermore, the shear rheology with applied E does not scale with γ˙E2, instead linear and sub-linear scaling with applied E is observed.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call