Nano-particle Suspension Rheology: Effect of Particle Size
The influence of particle size and volume fraction of solids as well as surface chemistry (pH and electrolyte concentration) on the rheological behaviour of alumina nano-particle suspensions was investigated. The shear yield stress (measured via the vane tool method), steady-shear viscosity and shear modulii were investigated. Three different types of alumina powders with average particle sizes of 11 nm, 44 nm and 190 nm are used in this investigation. The findings indicate that the rheological properties such as shear yield stress, shear modulus and shear viscosity of attractive particle networks increase inversely with the square of particle size. This result is consistent with pervious research on submicron alumina suspensions (200 to 800 nm) but extends the relationship to the order of 10 nm for the first time. An explanation of the underlying physical parameters controlling the inverse square particle size dependence of the suspension rheological properties is presented. The rheological behavior was found to be a powerlaw function of the suspension volume fraction with the powerlaw exponent varying between 4.5 and 5.5 depending on the particular rheological parameter investigated.