The effect of droplet extension on the rheology of emulsions of water in alkyd resin

We present experimental findings and matching modeling concerning the effec t of water droplets on the theology of a high viscosity alkyd resin. In the flow regime where significant droplet deformation occurs, the shear viscos ity of the fluid containing highly extended filaments was found to be lower than that of the alkyd resin on its own. A theoretical mechanism for this high shear rate viscosity reduction is proposed, and reasonable agreement i s established with experimental observation. At intermediate shear rates a crossover between viscosity enhancement and viscosity reduction correlates with a capillary number close to 1. At low shear rates classic viscosity en hancement was observed. (C) 2001 The Society of Rheology.