Analyzing the behavior of flows of polymers solutions and melts in the area of non-linear viscoelasticity allows to estimate more precisely the adequacy of the rheological model and to describe the material structure in more detail. Today a lot of models describe non-linear properties of polymeric materials rather accurately. However, the formulation of a uniform rheological model remains open. Therefore this work considers the modified Vinogradov-Pokrovsky rheological model which formed the basis for numerical calculations for periodic deformation of shear flows of polymeric liquids with a large amplitude. The non-linear viscoelastic properties shown in the course of the research of behavior of polymeric material at large deformations were studied by means of the immediate analysis of time dependence of shear stresses which were calculated at various amplitudes. It was stated that when increasing the amplitude of deformation the response stops being the exact harmonica, and a "step" on the left-hand front appears. It manifests the nonlinear response of a sample. The work compares obtained theoretical dependences and the experimental data for 5% mass solutions of the polyethylene oxide in dimethylsulfoxide which was studied at harmonic deformations with the large amplitude reaching 40 relative units. These dependences were measured at 35°C and the frequency of 0.2 Hz. Despite its simplicity, the modified Vinogradov-Pokrovsky rheological model shows good compliance with the experimental data. The results show that the chosen model adequately describes behavior of polymeric materials at large periodic deformations. Therefore this model may be applied for modeling more complex flows of fluid polymeric environments.

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