Compatibilizing and Toughening Blends of Recycled Acrylonitrile‐Butadiene‐Styrene/Recycled High Impact Polystyrene via Styrene–Acrylonitrile‐Glycidyl Methacrylate Grafted With Recycled High Impact Polystyrene

The recycling of mixed recycled acrylonitrile‐butadiene‐styrene (rABS) and recycled high‐impact polystyrene (rHIPS) from Waste Electrical and Electronic Equipment is hindered by thermodynamic immiscibility. In this work, a “waste‐to‐resource” upcycling strategy was developed using a pre‐grafted compatibilizer (SAG‐g‐rHIPS) that strategically exploits aging‐derived carboxyl groups as reactive sites. Synthesized via reactive extrusion, the compatibilizer functions through a synergistic dual mechanism: chemically anchoring the oxidized rubber phases while physically bridging the immiscible SAN and PS matrices through its amphiphilic architecture. This molecular reconstruction promoted molecular weight recovery of the degraded chains and refined the phase morphology from a coarse “sea‐island” structure to a more uniform dispersion. Consequently, the optimal formulation (S5H5) achieved a superior stiffness–toughness balance, maintaining a high tensile strength of 47.66 MPa while enhancing elongation at break by 71.73% and notched impact strength by 138.01% to 9.83 kJ m −2 , thereby enabling the high‐value recovery of rABS/rHIPS mixtures.