Grafting red clay with Bi₂O₃ nanoparticles into epoxy resin for gamma-ray shielding applications

We developed new composites for photons shielding applications. The composite were prepared with epoxy resin, red clay and bismuth oxide nanoparticles (Bi₂O₃ NPs). In order to establish which ratio of red clay to Bi₂O₃ NPs provides the best shielding capabilities, several different ratios of red clay to Bi₂O₃ NPs were tested. The transmission factor (TF) was calculated for two different thicknesses of each sample. From the TF data, we found that epoxy resin materials have a high attenuation capacity at low energy. For ERB-10 sample (40%Epoxy + 50% Red clay + 10% Bi₂O₃ NPs), the TF values are 52.3% and 14.3% for thicknesses of 0.5 and 1.5 cm (at 0.06 MeV). The composite which contains the maximum amount of Bi₂O₃ nanoparticles (40%Epoxy + 50% Red clay + 10% Bi₂O₃ NPs, coded as ERB-30) has lower TF than the other composites. The TF data demonstrated that ERB-30 is capable of producing more effective attenuation from gamma rays. We also determined the linear attenuation coefficient (LAC) for the prepared composites and we found that the LAC increases for a given energy in proportion to the Bi₂O₃ NPs ratio. For the ERB-0 (free Bi₂O₃ NPs), the LAC at 0.662 MeV is 0.143 cm^-1, and it increases to 0.805 cm^-1 when 10% of Bi₂O₃ NPs is added to the epoxy resin composite. The half value layer (HVL) results showed that the thickness necessary to shield that photons to its half intensity can be significantly lowered by increasing the weight fraction of the Bi₂O₃ NPs in the epoxy resin composite from 0 to 30%. The HVL for ERB-20 and ERB-30 were compared with other materials such as (Epoxy as a matrix material and Al₂O₃, Fe₂O₃, MgO and ZrO₂ as filler oxides in the matrix at 0.662 MeV. The HVL values for ERB-20 and ERB-30 are 4.385 and 3.988 cm and this is lower than all the selected epoxy polymers.