Bismuth oxide nanoparticles (Bi2O3 NPs) embedded into recycled- Poly(vinyl chloride) plastic sheets as a promising shielding material for gamma radiation

Abstract

In this work, novel γ-ray shielding materials based on recycled poly (vinyl chloride) (r-PVC) were prepared via melt mixing and compression molding technique. The designed materials are low-cost plastic wastes, ductile and lightweight, doped with xBi2O3 NPs (x = 0.0%, 5.0%, 15.0%, 25.0% and 35.0% (w/w)) as a non-toxic nanofiller. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to explore the characteristics of the as-prepared r-PVC/Bi2O3 nanocomposites. The γ-ray shielding effectiveness of the r-PVC/Bi2O3 nanocomposites were evaluated using NaI(Tl) scintillation detector at different γ-ray photon energies (121, 334, 778, 963, 1112 and 1408 keV) emitted from Eu-152 standard radioactive point source. For each of the mentioned photon energies, the mass attenuation coefficients (μm) were measured and compared to the Bi2O3 NPs’ doping ratio. The results showed that as the content of Bi2O3 NPs was increased in the nanocomposite, the value of μm significantly increased. In particular, the r-PVC nanocomposite sample containing 35.0 wt% Bi2O3 NPs exhibited the highest μm (2.5301 ± 0.22 at 121 keV). The μm was also calculated theoretically, using the MCNP5 simulation code. Experimental data of μm for all the tested nanocomposites were comparable to that obtained from a theoretical calculation. Moreover, the experimentally measured linear attenuation coefficient was the first step in calculating other shielding parameters, including half-value layer (HVL), tenth value layer (TVL), and mean free path (MFP). These parameters confirmed that addition of Bi2O3 NPs resulted in a higher shielding efficiency for r-PVC. Finally, this study shows that addition of Bi2O3 NPs to r-PVC facilitates the production of lead-free and sustainable polymer nanocomposites with improved γ-ray shielding characteristics, which can be used in nuclear energy applications, as alternatives to the shielding materials currently in use.