Nowadays, plastics account for a large part of our way of life because of a massive manufacturing and application in many fields. Nevertheless, due to serious environmental concerns, recycling and reuse have become of a great interest. Before achieving recycling step, several techniques are used for plastics sorting such as density measurement, or infrared. However, there is no distinction of the degradation level of each material that could enable to detect and exclude end-of-life plastic solid waste from the flow. WEEE are composed around 20-35 % of plastics that predominantly composed of acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), polypropylene (PP) with variable proportions. These latter will be consider as material of interest for our study. The purpose of the present work is to investigate the thermal degradation of ABS-HIPS and PP-PE blends derived from WEEE by extrusion process. Since we have highlighted that infrared technique may be unsuitable to detect chemical degradation such as oxidation, we propose to characterize degradation by measuring molar mass of the ABS-HIPS and PP-PE samples assessed by GPC that will be correlated to melt flow index (MFI) and rheology measurement to facilitate an industrial transfer. At last, the molar mass-mechanical properties relationship available in the literature have been applied to predict if the samples have a ductile or a brittle behavior, the latter considered as a criterion to exclude the sample from the recycling flow.