For the investigation of the thermal stability of plastic melts, dynamic scanning calorimetry (DSC), thermogravimetric analysis (TGA) or the viscosimetry are used. It has to be considered that possible effects appearing during the extrusion process are ignored. Such influencing variables are the pressure and a temperature increase due to dissipation. Therefore, a new measurement system has been developed capable of quantifying the stability of the polymer under process conditions. Simultaneously, a corrosive effect between the melt and the metallic surface (surface-melt-interaction) can be investigated. The measurement system is based on a cylindrical test sample, which is surrounded by a heated barrel, which is manufactured from a non-reactive material. Furthermore, the sample is connected to a drive that allows a controlled rotational motion. The variation of the rotation speed enables to realize different shear rates in the gap (1.7 mm) between the barrel and the test sample. The adjustable shear rate is up to 150 s-1. For the plasticizing of the material, a laboratory extruder is used. The extruder is needed to convey the material into the annular gap. To exclude early reactions during the extrusion process between the material and the metallic surface, the screw and the extruder barrel are manufactured from a non-reactive material, too. Furthermore, the residence time of melt in the system is exactly defined. Additionally, the system made possible to extrude films for additional test. Achieved results with the measurement concept will be shown in the presentation and the paper.