Analysis of X-ray and gamma ray shielding performance of prepared polymer micro-composites

Abstract

Polymethyl-methacrylate (PMMA) was used as the matrix to prepare micro composites for radiation shielding, with 10%, 20%, 30%, and 40% Bi2O3 filler loadings, by melt mixing method. The mass attenuation coefficients (MAC) of prepared micro composites along with pure PMMA were measured with a NaI (Tl) scintillator detector spanning a wide range of energies (59–1332 keV). Several radioactive point sources, which are commonly used in many industrial and medical applications, namely Co-60 (1173 and 1332 keV), Co-57 (122 keV), Cs-137 (662 keV), Am-241 (59.6 keV), Ba-133 (81 and 356 keV) and Ra-226 (242 keV), were used in the experimental work. The shielding performance increased substantially with increasing Bi2O3 filler loading especially in the low energy range and decreased with increasing energy except at 122 keV due to bismuth K-absorption edge. At higher energies 1173 and 1332 keV, Compton effect is the most dominant effect leading to minor variations as observed. XCOM software was used for comparison, by computing the mass attenuation coefficient for prepared micro composites at all used Bi2O3 loadings including pristine PMMA. In addition, the effective atomic number Zeff, electron density Neff as well as the photoelectric absorption and incoherent scattering contributions to MAC, were evaluated for further analysis. The prepared PMMA-Bi2O3 micro composites shielding materials performed very well in the whole energy range 59–1332 keV of interest to medical and industrial applications, and are excellent at lower energies and higher Bi2O3 loadings. In particular, at 40% loading, the experimental MAC for the Cs-137 gamma line (662 keV) reached 93.4% of that of lead element. Therefore, these composites are much recommended cost effective, light and safe shielding material for x and gamma rays.