Modeling of the Devolatilization Process in an Extruder
Sprache des Vortragstitels:
Polymer Meeting 14
Sprache des Tagungstitel:
The devolatilization of the polymer melt during polymer extrusion plays a crucial role in ensuring the quality of the recyclates. In order to remove the undesired volatile constituents (so-called VOCs) from the polymer melt, vented screw extruders are often used. Single- or multi-shaft screw machines are used, with devolatilization taking place under atmosphere or vacuum. To increase the devolatilization efficiency and to prevent the melt from flowing out of the degassing openings, devolatilization zones are operated partially filled. When designing extruder screws for polymer extrusion, the prediction of the devolatilization performance is extremely important. The literature provides only few theroretical modeling approaches to estimating mass transport processes in the degassing zone of extruders. Most of these models describe this process via bubble-free diffusion on the free surfaces. We present a comparative study of three models from literature based on different theories. The models are validated with experimental extrusion data to allow an assessment of the predictions accuracies of the models. The aim is to be able to make a statement as to which model reflects the experimental extrusion data qualitatively well.