<title>Static and dynamic dielectric properties of 6-OCB and 8-OCB</title>

Abstract

Static electric permittivity and dielectric relaxation have been measured in isotropic and nematic phase of 6-OCB and 8- OCB. On the basis of the temperature dependence of the principal static permittivities of nematics, (epsilon) (parallel)(T) and (epsilon) (perpendicular)(T), using the Maier-Meier equations, the following quantities have been obtained: i) the angle between the dipole moment vector and the long axis of mesogenic molecules, ii) the molecule apparent dipole moment square (mu) <SUP>2</SUP><SUB>app</SUB>(T) and iii) the nematic order parameter S(T). From the temperature dependence of the dielectric relaxation time, the activation energy for the molecular rotation around the short axis has been calculated and, taking into account the viscosity data, the effective dimensions of the nematogen molecules have been evaluated.