In this study, polyethylene degradation is related to its the thermomechanical history from processing in a batch mixer. A focus is made on the rheological and molecular properties of the polyethylene subjected to different processing conditions by changing the temperature, the rotor speed and the time of process. The results indicate that while shear theological properties changed slightly, the elongational properties were substantially modified, especially the maximum stress and the elongation at break. Due to the formation of macro radicals while processing, macromolecular changes were characterized in terms of molecular weight distribution and the results represent a balance between rates of chain scission and chain branching. It was found that the main parameter to characterize the degradation behaviour was the input power.