During the processing of thermoplastics, polymers are subjected to high stress. As a resultof this stress, the polymer chains break, leading to a lower molar mass. This further leads to a lowerviscosity of the plasticmelt and, eventually, to poorermechanical properties of themanufactured plasticproduct. Especially in the context of recycling plastics, this poses a challenge to process technologyand product properties. This work aims is to provide a prediction of the material degradation underknown stress, so that, for example, a process design that is gentle on the material can be carried out.In order to be able to predict material degradation under a load, a test stand for defined materialdegradation was designed. The test stand allows for material damaging under a defined temperature,shear rate and residence time. At the same time, the test stand can be used to measure the viscosity,which is used to describe the degradation behavior, since the viscosity correlates with the molar mass.The measured decrease in viscosity under stress can be used to predict material damage under theinfluencing variables of temperature, shear rate and residence time by means of a test plan and asuitable mathematical description of the measured data. The mathematical description can thus beintegrated into simulation environments for plastics processing, so that a simulation of the materialdegradation can be carried out, if necessary also taking the viscosity reduction into account.