Modeling of mixing process of the polymer composition in the dynamic mixer of the worm extruder

Abstract

Mixing processes play an important role in the processing of polymer materials, because the quality of the mixing of the polymer material depends on its level of homogeneity, which in turn affects the quality of the final product. It is another matter when the polymer material consists of two or more components, in this case, the issue of the process of obtaining a homogeneous polymer composition becomes extremely acute. In order to improve the quality of the final product and justify the design and technological parameters of the mixing zone, it is necessary to investigate the regularity of the quality of mixing in a dynamic mixer of the CTM worm extruder type. According to existing works on determining the quality of mixing of polymeric material, the difference in concentrations of one of the components in different cross-sections along the length of the channel can be used as a criterion for homogeneity of mixing. Numerical modeling of the process of mixing the polymer composition in the dynamic mixer installed in the dosing zone of the worm extruder, which is equipped with an additional injection device that supplies the additional component to the dynamic mixing zone through the injection channel located in the body of the worm extruder, was carried out. Calculations were carried out on the basis of the finite element method (FEM) using the ANSYS software complex. A mathematical model of the process of mixing the polymer composition in a dynamic mixer of the CTM type of a worm extruder with the addition of an additional component, which is identical in density and viscosity to the main polymer material and can differ only in a certain feature that does not affect the properties of the components, such as color, has been developed. Moreover, the properties were set in such a way that the temperature distribution of the mixture was completely determined by the convective component, that is, it resulted only from the conditions of the mechanical movement of the volumes of the components. The dependence of the homogeneity of the polymer composition as a result of mixing on the technological and design parameters of the dynamic mixer of the CTM type was obtained. The research was carried out at different speeds of rotation of the mixer rotor and at different speeds of supplying the additional component. The movement of the components of the mixture was determined by their flow rate at the entrance to the main channel and at the entrance to the additional injection channel. The most optimal technical characteristics were selected in order to achieve the best level of uniformity.