Comparative analysis of rheological properties indicators for thermoplastic melts

Abstract

The introduction analyzes the state of the issue and substantiates the research relevance. The aim of the work is to determine and comparatively analyze the values of physically normalized indicators of rheological properties of typical representatives of thermoplastic melts. In the methodological part of the work, to ensure the comparability of the results, the physically normalized form of the Ostwald-de-Waele power empirical rheological equation proposed by McKelvey is used. The calculation scheme is based on the transition from an approximating power function with rheologically non-deterministic parameters to two dimensionless rheologically determined complexes characterizing the stress-strain state of a nonlinear-viscous medium. The first dimensionless complex is presented in the form as the ratio of the actual shear rate to a unit normalization base value, and the second is in the form as the ratio of shear stresses acting on the deformable medium to the base (reduced) value of these stresses, which are necessary to overcome viscous resistance at a unit normalization shear rate. A technique is described for determining physically normalized indicators of rheological properties using the thermoplastic melts flow curves available in the scientific and technical literature (dependence of shear stresses on shear rate) based on the processing of these graphical dependencies plotted in double logarithmic coordinates. In the main part of the work, the values of physically normalized indicators of rheological parameters (the reduced index of viscous resistance and the indicator of the rheological nonlinearity of the melt) are determined and presented in the form of tables for widely used types of filled and unfilled thermoplastic polymers. A comparative analysis of these indicators has been carried out. Conclusions are given on the work and it is noted that the results of the research can be used in engineering practice, as well as in the educational process when performing rheological calculations of the processes of processing thermoplastic polymeric materials.