Anisotropy in nonlinear polymer rheology

A theory describing the behavior of liquids with anisotropic relaxation times in terms of the extended (locally nonequilibrium) thermodynamics of irreversible processes has been formulated. The theory forms the basis for a general approach to the investigation of anisotropy of the rheological properties of orientable polymer liquids. Uniaxial shear and elongation flows of a viscoelastic fluid in one preferred direction have been considered. The pattern of the obtained viscometric functions indicates the important role of macroscopic orientation effects in the rheology of polymeric media.