Investigation of the barrel temperature profile on the process behavior of single screw extruders and strategies to determine the optimal temperature control

Abstract

At present, polymer extrusion is one of the most important manufacturing processes due to the increasing demand of polymer products. In order to reach the desired amounts of polymer, the melt quality of the polymer plays a crucial role. The melt quality is not solely dependent on the chemical composition of the base polymer but also on the condition of preparing and processing the polymer. Indeed, the resulting melt quality is highly dependent on the parameter settings of the extruder. Since polymer materials have a temperature-dependent behavior, the temperature progress over time is one significant aspect. Hence, the thermal stress of the polymer particles during the extrusion process is essential to preserve a good melt quality. In the wake of this, the determination of a decent barrel temperature along the extruder is one of the primary challenges in the field of extrusion. Besides, generating a thermal homogeneous polymer melt, a progression of the throughput, consequently an increase of the economic efficiency, is possible. In return, an inauspicious barrel temperature can lead to a deterioration of the material properties and in this manner, it will lead to a decrease in the economic efficiency. In addition to that, the thermal radial melting profile and the pressure fluctuations of the melt during the process is significantly influenced by the barrel temperature. Furthermore, with respect to high pressure fluctuations, an inopportune barrel temperature setting can lead to a substantially higher wear of the screw and the barrel. In this article the effect of different barrel temperature profiles on the process behavior is in the focus. Firstly, different criteria for defining or respectively measuring the melt quality are considered. After that, two different strategies to determine a convenient barrel temperature setting are taken into account. The collected target figures are utilized to find correlations between the barrel temperature setting of each barrel zone and the polymer melt quality.