The effect of the geometry of extrusion head flow channels on the adiabatic extrusion of low density polyethylene

Abstract

Abstract Plastics extrusion can be divided into the following types: conventional extrusion (run at low speed of the rotating screw), adiabatic extrusion (screw speed is relatively high, yet the process requires the use of heaters) and high speed extrusion (extruder barrel requires cooling due to very high screw speeds). This paper presents the results of a study undertaken to investigate the adiabatic extrusion of low density polyethylene using heads with circular cross-section nozzles and different geometries of flow channels. In the experiments, we examined the temperature and pressure of the polymer in the plasticizing unit, as well as the relationships between the output, thermal power conveyed by the plastic, total power supplied to the extruder, extrusion efficiency, unit consumption of the total energy supplied to the extruder as well as the rotational speed of the screw and the extruder’s head geometry. It was found that the most favorable energy conditions, i.e., the highest efficiency of the adiabatic extrusion of low density polyethylene in the whole range of the tested screw speeds, are ensured when the head with the highest diameter and length nozzle is applied.