Shear thickening in dilute solutions of wormlike micelles

A new mechanism is suggested for shear thickening in dilute solutions of wormlike micelles. According to this mechanism, there is an instability above a critical shear rate, (gamma) over dot(c), by which micelles aggregate to form networks of bundles. We examine the rst step of this instability by studying the aggregation of two micelles into a paired bundle. The model predicts that (gamma) over dot(c) is given by the inverse of the time necessary for the two micelles to unbind from each other. The order of magnitude and temperature dependence of the predicted (gamma) over dot(c) are in good agreement with experimental measurements. In addition, the model provides a natural explanation for the observation of coexistence between the shear-induced structure and a dilute phase at fixed shear stress.