TEXTILES.ORG
ExxonMobil, Milliken and Ravago have developed high-performance polypropylene (PP) compounds that incorporate recycled content and meet various automotive requirements. These requirements include stiffness, impact resistance, and fast injection molding cycle times, which comply with emerging end-of-life vehicle requirements in the European Union.
Automotive original equipment manufacturers have traditionally limited the use of recycled PP to non-critical automotive parts due to challenges in balancing mechanical performance, processing efficiency, and regulatory compliance.
ExxonMobil and Milliken initially partnered to develop PP formulations using mechanically recycled material combined with Exact polyolefin elastomers from ExxonMobil and DeltaMax additives from Milliken. Multiple compounding trials focused on meeting automotive specifications for flexural modulus, tensile strength and impact resistance at both ambient and sub-zero temperatures, while also improving melt flow.
The resulting compounds demonstrated melt flow rate improvements of more than twofold compared with baseline recycled PP materials, enabling faster injection molding cycles and lower processing temperatures. The formulations also maintained stiffness benchmarks required for functional automotive parts while delivering strong impact resistance.
Following the initial trials, the collaboration expanded to include Ravago, which evaluated a formulation incorporating Ravapura, containing 25% certified post-consumer recycled content, including materials from end-of-life vehicles.
Testing results showed melt flow rate improvements of up to 200%, while Charpy impact strength increased by as much as 660% at room temperature and up to 200% at -30 C (-22 F). Mechanical performance approached that of virgin PP grades.
The results of the case study are available here.