Normal Stresses in the Rheology of Structured Systems

A structural-kinetic model, which allows us to obtain two rheological equations for describing the dependence of the first difference of normal stresses on the shear rate in the region of low rates and in the region of high shear rates, is considered. The obtained equations are approximated to the experimental data for various structured systems, namely, melts and polymer solutions. The regularities of the change in the coefficients of the rheological equations with a change in the concentration of the polymer in the solution and with a change in the molecular weight of the polymer are explained in terms of structural-kinetic concepts.