Mechanical Recycling of the Mixed Waste Plastics: Janus Nanosheets as Compatibilizer for Ternary Blends

Mixed plastic streams composed of immiscible polymers suffer from poor interfacial adhesion and a loss of mechanical performance, which limits the value of mechanically recycled plastics. In this work, Janus nanosheets (JNs) are employed as interfacial compatibilizers in model binary and ternary blends comprising polypropylene (PP), polyamide 6 (PA6), and polystyrene (PS) polymer blends, as well as in blends where PP has undergone an additional melt-reprocessing step (re-extruded PP, rPP). The unique amphiphilic structure of JNs promotes their localization at the interfaces, thereby suppressing phase separation and improving the mechanical performance. Quantitative analysis reveals substantial enhancements in both the tensile strength and elongation at break. The incorporation of JNs results in a 21.1% increase in the elongation at break for blends with virgin PP and an even greater improvement of 34.8% in blends containing rPP. Scanning electron microscopy analysis reveals corresponding enhancements in the blend morphology and interfacial structure. These results demonstrate that JNs can compatibilize highly contaminated model PP/PA6/PS blends and remain effective in blends containing rPP, indicating robustness under an additional melt history, while paving the way for more sustainable recycling processes.