The rheology of thermoplastics under conditions of spiral flow and vibrations on extrusion

Abstract This paper describes the results of a theoretical and experimental study on the rheology of thermoplastics subjected to mechanical effects at extrusion conditions. The spiral flow of non‐Newtonian systems has been studied and quantitative relationships obtained for its description, which are suitable for engineering. The effect of rotational low‐frequency large‐amplitude vibrations on the flow of melts in the extruder's head of simple (circular) and complex cross sections has been studied and an analysis provided for flow with small‐amplitude high‐frequency (ultrasonic) superimposed vibrations. The energy efficiency of cyclic deformation upon extrusion has been estimated. The investigation has provided recommendations for the application of complex shear as a method of directed action on the relaxation and, hence, rheological characteristics of polymers. This opens up new possibilities for the intensification of the extrusion processes and compositions based on thermoplastics.