Radiation shielding and mechanical properties of epoxy-based composites reinforced with Sb2O3, carbon fiber, and basalt fiber

In this study, the radiation shielding performance of epoxy-based composites reinforced with antimony trioxide (Sb2O3), carbon fiber, and basalt fiber was systematically investigated together with their mechanical and microstructural characteristics. Composite specimens with different filler configurations were fabricated using mechanical stirring combined with ultrasonic homogenization. Gamma-ray attenuation measurements were performed using a high-purity germanium (HPGe) detector and a Ba-133 radioactive source in the photon energy range of 79.6–383.9 keV, and the experimental results were compared with theoretical calculations obtained from the WinXCOM database. The mass attenuation coefficient (MAC), effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), and mean free path (MFP) were evaluated to assess shielding efficiency. The results indicate that the incorporation of Sb2O3 yields more favorable gamma-ray attenuation behavior, particularly reduced HVL and MFP values in the medium-energy range, with the specimen with the highest Sb2O3 content, RT4, exhibiting the most pronounced improvement. Mechanical tests reveal that the addition of Sb2O3 and hybrid fillers results in reductions in compressive and flexural strengths compared to neat epoxy, which is attributed to particle agglomeration and interfacial discontinuities. These observations are supported by microstructural analyses, which highlight filler-induced changes in dispersion and structural integrity. Overall, the findings demonstrate that epoxy/Sb2O3-based composites can offer an effective balance between radiation-shielding efficiency and mechanical performance, underscoring the importance of filler optimization for lead-free gamma-ray shielding applications.