Shear banding instability in wormlike micellar solutions

摘要: Using NMR velocimetry and mechanical measurements we study the flow dynamics, within a cone-and-plate rheometer, of wormlike micelle system, cetylpyridinium chloride/sodium salicylate (CPyCl/NaSal) at 100 mM/60 mM concentration in distilled water. Depending on precise conditions two classes behaviour are observed, one which boundary between different shear rate phases fluctuates rapidly (on order tens milliseconds) it migrates slowly with time constant many seconds. These modes may depend minor solution impurities, presumably affect detailed constitutive properties, but also externally applied given system. We argue that slow migrations governed by stress relaxation effects while rapid driven arise from interfacial instability.