Viscosity of sponge phase in porous medium

(Received 25 July 1991, revised 18 November 1991, accepted 21 November 1991)

Abstract
Sponge phases are phases of randomly connected membranes. We present an experimental investigation of their rheological properties. Both data on the "bulk" viscosity and the effective viscosity through pores are presented. When the bulk viscosity is of the order of a few times the solvent viscosity and is Newtonian in the accessible shear rates (10 ^-2-10 ² s ^-1), the flow of the sponge through cylindrical pores leads to non-Newtonian behaviour. At low shear an enhanced viscosity as the sponge size approaches the pore diameter is observed, while at larger shear rates, the apparent viscosity saturates towards a smaller value close to that measured in the bulk. A simple model based on obstruction and deformation is introduced to describe these different regimes.