Molecular Crystals and Liquid Crystals, Vol.378, 103-112, 2002
Rheological study on the shear-induced structural changes in liquid crystalline phases of octylcyanobiphenyl
In the nematic (Ne) and the smectic A (SmA)phases of octylcyanobiphenyl (8CB), a steady shear flow induces various dynamical structures which do not appear in the absence of the shear flow. To make clear the relationship between these structures and the rheological properties, some rheological measurements, including the electrorheological(ER) effect, which is the effect of an electric field on rheology, are made. We find that the temperature dependence of the viscosity, the fluidity, and the ER effect show characteristic behaviors which can be understood on the basis of the reported shear-induced structures. These rheological properties are discussed in terms of the orientational changes of the director and/or the smectic layer and the critical effect of the Ne-SmA phase transition.