| Abstrakt: |
The co-kneader is widely used in the plastic industry for compounding of shear and temperature sensitive materials, due to its high mixing performance and its exact temperature control capabilities. The design of the machine, however, is still predominantly carried out by trial-and-error based experimental work. One reason for this is that, in contrast to other extruders, only few process models and no simulation programs are available for the kneader. To address this problem, we already have developed a basic analytical model in previous work. With this model, the melt transport and the melting process in the kneader can be described. Building on this work, a comparison of simulation and experimental investigation of the melting behavior for different process points and configurations of the co-kneader was conducted and is presented in this paper. The simulation results show a satisfactory agreement with experimental results when the start of melting, as assumed in the model, coincides with the material backlog before the first fully filled kneading element. However, the presented experimental investigations also show that this assumption is not true for all configurations considered. In particular, if the kneader is operated without a constriction ring at the end of the intended plasticizing zone, for polyethylene only a plastic deformation of the pellets occurs, but no melting. The start of melting will therefore be investigated in future work, as a function of the particle diameter. [ABSTRACT FROM AUTHOR] |
