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Measurement of viscosities from the transient current of nematic liquid crystals with negative dielectric anisotropy |
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| Authors: | Yosuke Iwata Hiroyoshi Naito Masaru Inoue Melanie Klasen-Memmer |
| Affiliation: | a Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan b The Research Institute for Molecular Electronic Devises, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan c FPD Measurement System Project, TOYO Corporation, 1-1-6 Yaesu, Chuo-ku, Tokyo 103-8284, Japan d Liquid Crystals Division, Merck Ltd., 4084 Nakatsu, Aikawa, Kanagawa 243-0303, Japan e Liquid Crystals Division, Merck KGaA, Frankfurter Strasse 250-64293 Darmstadt, Germany |
| Abstract: | A method for measuring the complete set of the Leslie viscosity coefficients of nematic liquid crystals (NLCs) with negative dielectric anisotropy (Δε < 0) is proposed. The method is based on the analysis of the transient current, induced by step voltage excitation, in homeotropic NLC cells. It has been shown that the transient current in homeotropic NLC cells with Δε < 0 can be explained by the theory of NLCs in which the flow effects and the free-slip boundary condition are taken into account [Y. Iwata et al., Jpn. J. Appl. Phys. 43 (2004) L 1588]. It is demonstrated that the complete set of the Leslie viscosity coefficients of NLCs with Δε < 0 can be simultaneously and accurately measured by fitting the transient current calculated by the theory to the experimental data with a differential correction method. |
| Keywords: | Nematic liquid crystal Viscosities Negative dielectric anisotropy Transient current Flow effects |
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