Enhanced radiation shielding efficiency of polystyrene nanocomposites with tailored lead oxide nanoparticles

Abstract

In this study, we investigated a novel polymer nano-composite, PS-PbO, containing two distinct nano-sizes of lead oxide nanoparticles (PbO-A and PbO-B), in addition to the bulk size (PbO-K). These nanoparticles were embedded separately in a polystyrene (PS) matrix at different weight percentages (10%, 15%, 25%, and 35%) using roll mill mixing and compressing molding. Our evaluation focused on the radiation attenuation ability of PS-PbO and the effect of particle size, considering gamma-ray energies ranging from 0.06 to 1.3 MeV (from sources like ²⁴¹Am, ¹³³Ba, ¹³⁷Cs, and ⁶⁰Co). The linear attenuation coefficient (LAC) was determined by analyzing samples of the synthesized composite with different thicknesses. Then, various shielding parameters were calculated, including total molecular, atomic, and electronic cross-sections (σ_mol, σ_atm, σ_el), as well as the effective atomic number and the electron density (Z_eff and N_eff). Surprisingly, modifying PbO particle sizes had a significant impact on shielding efficiency. For instance, the composite with 25 wt% of the smallest PbO-B particles showed a 26.7% increase in LAC at 0.059 keV compared to the composite with 25 wt% of PbO-K (larger particles). Notably, the LAC peaked at low energy (0.059 keV), close to the K-edge of Pb, where interaction is directly proportional to Z⁴. With increasing PbO concentrations, the LAC of PS-PbO composites increased steadily. Additionally, as PbO concentration increased, the composite’s effective atomic number Z_eff and the electron density N_eff increased, leading to a greater total Gamma-ray interaction cross-section. Furthermore, when comparing the Half-Value Layers of the novel nanocomposite to traditional lead shielding, a 70% reduction in mass was observed. Notably, the composite containing the smallest nano-size of PbO exhibited the highest radiation-shielding efficiency among all combinations and could therefore be used to create inexpensive and lightweight shields.