High-loading composites based on waste-derived expanded polystyrene for lead-free X-ray shielding applications

Expanded polystyrene (EPS)–based composites derived from recycled materials were developed using an innovative processing route to obtain lead-free X-ray shielding materials incorporating high contents of tungsten and bismuth oxide. Recycled EPS was selected due to its lightweight nature, availability, and sustainability advantages, while still offering adequate structural performance when properly processed. The effectiveness of a carbon filler, namely graphene nanoplatelets (GNP), as a secondary additive in the composite systems was also investigated. The composites were characterized through flexural testing, thermogravimetric analysis, and morphological evaluation, while their X-ray attenuation capability was assessed via both numerical simulations and experimental measurements. Despite the elevated filler loading (75 wt%), a homogeneous distribution of tungsten and bismuth oxide within the polymer phase was achieved, conferring good mechanical properties to the composites. Within the investigated energy range (50–150 keV), effective X-ray shielding equivalent to lead was obtained. This performance was achieved at thicknesses corresponding to a moderate mass increase (approximately 24–53%) compared to conventional lead shielding providing equivalent attenuation. These results highlight the potential of recycled EPS-based composites as a new class of sustainable, lead-free X-ray shielding materials.