Using Polypropylene-Based End-of-Life Vehicle (ELV) Recyclates in Practice: Contaminant and Composition Effects on Performance

Mechanical recycling of polypropylene (PP)-based plastics from end-of-life vehicles (ELVs) is a key route to increase circularity in the automotive sector, but the practical use of ELV recyclates is limited by compositional variability and contamination, especially paint residues. In this study, a PP-based ELV bumper recyclate was compared to a virgin mineral-reinforced and elastomer-modified automotive PP compound and incorporated as a drop-in component at up to 35 wt.-%. Composition was assessed by differential scanning calorimetry, thermogravimetry, and CRYSTEX analysis, while contamination was quantified by computed tomography and related to tensile, impact, and instrumented puncture properties. Mineral and elastomer contents of the ELV recyclate were comparable to the virgin reference after re-stabilization, enabling blends with limited stiffness loss. However, ductility and toughness decreased with increasing recyclate content, especially at low temperature, due to the combined effects of elastomer degradation and rigid contaminant inclusions. Melt filtration of the recyclate substantially reduced the volume fraction of inclusions, removing particularly the largest particles greater than 100 µm, and thereby improved strain at break and puncture performance. Double filtration at 35 wt.-% recyclate loading achieved 50–85% of the virgin-reference ductility and toughness levels and nearly retained the stiffness. These results demonstrate that PP-based ELV recyclates can be used in high-impact automotive formulations at contents exceeding current long-term regulatory targets with recipe modification being limited to further stabilizer addition, provided that contaminant control and elastomer-phase quality are adequately managed.