Upcycling High Impact Polystyrene Post‐Consumer E‐Waste Into Composites by Thiocracking

Electronic waste (e‐waste) contains large fractions of engineering plastics that are challenging to recycle because they are distributed across many products, compounded with additives, and often contaminated. Here we demonstrate a one‐pot thiocracking strategy that converts post‐consumer high‐impact polystyrene (HIPS) into high‐sulfur composites using only elemental sulfur and mechanically processed HIPS. Heating mixtures of sulfur and HIPS at 230°C affords a formulation series (HIPSS70–HIPSS90, 70–90 wt.% S) as dark brown monoliths in 91–95% isolated yield without solvent or catalyst. Solvent extraction followed by UV–vis analysis quantifies 14.9–27.6 wt.% extractable (‘dark’) sulfur, indicating formulation‐dependent sulfur immobilization. SEM‐EDX mapping is consistent with a comparatively uniform sulfur‐rich matrix in HIPSS 90 and discrete carbon‐rich domains at higher HIPS loadings. Thermal analysis shows sulfur‐dominated transitions ( T g −36 to −5°C; T m ≈115°C–117°C) with additional higher‐temperature glass transitions in HIPS‐rich composites, and decomposition onsets near 228°C–233°C. Compressive strengths of 5.9–9.3 MPa place the HIPS composites in the regime of masonry bricks and comparable waste‐derived high‐sulfur materials, supporting their potential as low‐cost construction and encapsulation materials for plastic‐rich e‐waste fractions.