17:00
In highly concentrated surfactant solutions the surfactant molecules self-assemble into long flexible "wormy" structures. Properties of these wormlike micellar solutions make them ideal for use in oil recovery and in body care products (shampoo). These properties depend strongly on temperature and concentration conditions. In solution the "worms" entangle, forming a network, but also continuously break and reform, thus earning the name ‘living polymers’. In flow these fluids exhibit spatial inhomogeneities, shear-banding, and dynamic elastic recoil. In this talk a rheological equation of state that is capable of describing these fluids is described The resultant governing macroscale equations consist of a coupled nonlinear partial differential equation system. Model predictions are presented, contrasted with experimental results, and contrasted with predictions of other existing models. Generalizations of the model to allow the capturing of behaviors under changing concentration or temperature conditions, namely power law and stretched exponential relaxation as opposed to exponential relaxation, will be discussed and particularly a mesoscale stochastic simulation network model will be presented.