Orientation Correlations in the Isotropic State of Low Molecular Weight and Polymeric Fluids

Abstract

The short range orientational order characteristic of molecular fluids is discussed as a function of the shape of the molecules and of intermolecular interactions. Low molecular weight and polymeric substances exhibiting only an isotropic melt or, in addition, liquid crystalline phases were taken into account. The discussion is based on experimental results obtained from dielectric relaxation, Kerr effect and X-ray studies. The characterization of the short range order is given in terms of correlation parameters, related to the general pair correlation function.