Rheologica Acta, Vol.47, No.8, 883-894, 2008
Squeeze-flow and vane rheometry of a gas-liquid foam
The rheology and slip of a dry shaving foam are investigated using squeeze-flow and rotating-vane methods. Constant-force squeeze flow between planar surfaces is used to study the effect of surface roughness on slip and to obtain the yield stress. Non-slip vane measurements are used to obtain the linear shear viscosity and elasticity at small strains, and the yield stress and strain at large strains. Data are compared with the small-strain Maxwell and Kelvin-Voigt linear-viscoelastic models. An apparent dependence of the yield stress and elasticity on the rotational speed of the vane is shown to result from time-dependent rheological parameters as the foam ages. The effect of viscosity in the pre-yield region may give an erroneous identification of yield.
Keywords:Rheometry;Squeeze flow;Vane;Foam;Slip;Yield stress;Viscoelasticity;Maxwell model;Kelvin-Voigt model