Investigating the Effect of Liquid State Decontamination on the Material Properties of Post-Consumer High Impact Polystyrene Recyclate

The global focus on environmental sustainability has intensified the need for innovative plastic waste management solutions, especially in the food packaging industry. This study explores liquid state decontamination processes of recyclates produced by post-consumer waste recycling of polystyrene yogurt cups and their effects on the material properties of the recycled material. For this purpose, different decontamination processes based on a twin-screw extruder with vacuum degassing and an industrial-scale recycling machine were applied. Tests such as tensile testing, Charpy impact testing, melt flow rate (MFR) measurement, plate-plate rheometry, high-pressure capillary rheometry (HCR), and differential thermal analysis (DTA) were conducted to assess the mechanical and thermo-rheological properties as well as the oxidation induction temperature as an indicator of polymer degradation. The findings provide a comprehensive understanding of the achievable properties of polystyrene from post-consumer waste and reveal insights into the different process-induced degradation processes of the recycled polystyrene.