Synergistic Effect of Nano‐ WO ₃ and Micro‐ Bi ₂ O ₃ Hybrid Fillers on X‐Ray Attenuation of Epoxy Nanocomposites in the Experiment and Simulation

ABSTRACT For decades, an enhanced X‐ray shield has been the subject of many research studies. However, the synergistic effect and optimal ratio of bi‐modal fillers in a hybrid epoxy composite have not been fully investigated. The X‐ray attenuation properties of Bi ₂ O ₃ microparticles and WO ₃ nanoparticles were investigated in an epoxy matrix through the optimization of filler ratios, both individually and in a hybrid dual filler nanocomposite, across varying weight percentages (1–10 wt%) and ratios, by both the standard X‐ray tube used for industrial radiography and a 120 kVp CT scanner and by the Monte Carlo simulation using the Geant4 simulation toolkit. Optimal X‐ray attenuation was observed for the composite with WO ₃ nanoparticles compared to Bi ₂ O ₃ microparticles in single filler nanocomposites. For instance, adding 10 wt% WO ₃ nanoparticles at a 0.5 cm thickness yielded a CT number of 803.89 and a mass attenuation coefficient (MAC) of 0.347 cm ² /g. The highest CT number, 981.85, was achieved in a hybrid nanocomposite with 5 wt% WO ₃ + 5 wt% Bi ₂ O ₃ , with a MAC of 0.3898. The study advocates for the fabrication of a hybrid nanocomposite with 5 wt% nano‐WO ₃ + 5 wt% micro‐Bi ₂ O ₃ for superior X‐ray attenuation, paving the way for advancements in effective radiation shields.