Analysis and modelling of the melting behavior of polymers in co-kneaders

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The gentle processing of plastics is a central component in the cycle of plastic products, particularly because of the constantly growing importance of biopolymers and recycling. In this context, the Co- Kneader represents a machine system which, based on its excellent homogenization properties and the low shear stress of the material, is well suited for demanding processing tasks. Due to the lack of models for this type of machine, the development of the Co-Kneader to today's degree of maturity is largely based on empirical knowledge and trial-and-error methods. Because of increasing requirements and more complex processes, this is increasingly becoming a problem. This is why the use of simulations has established itself in the development of extruders. Although first models have been published for Co-Kneaders to describe the process behavior, they neglect melting and are therefore only valid for pure melt conveyance. The aim of this project is therefore the investigation of the melting behavior of plastics in Co-Kneaders. In the first funding period, basic physicalmathematical models were developed to describe the melting processes. It was possible to describe the melting of granulates in the Co-Kneader with a disperse melting model. However, the models only lead to valid results if the melting corresponds to the location of the first full filling. In addition, energy input via plastic energy dissipation is neglected. In the second funding period, therefore, the modelling of the initial melting is to be improved. For this purpose, plastic energy dissipation will be modelled. Results from experimental investigations at the Co-Kneader as well as mechanical parameters will be used for the calibration of the models.