S0520202 大振幅せん断振動におけるひも状ミセル水溶液のシアバンド形成過程

抄録

The formation process of Shear-bands in a wormlike micellar solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) in the large amplitude oscillatory shear (LAOS) is examined experimentally. A transient response of shear stress after applying a large amplitude sinusoidal strain is measured by rheometer with concentric cylinder. In order to observe the spatial distribution of the optical anisotropy in the flow field, a new visualization technique recently developed by the authors, which can evaluate distribution of both the birefringence and the orientation angle from a photograph taken by the crossed-Nicols method, was applied. The highly-birefringent layer was formed near the moving wall when the strain exceeds 2.3 in the LAOS flow. In the oscillation with the higher strain, the shear-bands are formed but the bands disappeared at when the strain turns to zero. Therefore, the formation and dissipation of the shear-bands are repeated in each cycle of the LAOS flow.