In the present work, high density polyethylene (HDPE) matrix mixed with micro-sized and nano-sized Cadmium oxide (CdO) particles of different concentrations were prepared by compression molding technique. The aim of the study is to investigate the effect of particle size and weight percentage of CdO particles on the gamma radiation shielding ability of CdO/HDPE composites. The mass attenuation coefficients of pure HDPE, micro-CdO/HDPE and nano-CdO/HDPE composites were evaluated at photon energies ranging from 59.53 keV to 1408.01 keV using standard radioactive point sources [241Am, 133Ba, 137Cs, 60Co and 152Eu]. Adding micro and nano CdO particles to the HDPE matrix clearly increases the mass attenuation coefficients of the composites and the improvement is more significant at low γ-ray energies. The effect of particle size of CdO filler has an important role on the shielding ability of the composite. The experimental results reveal that, the composites filled with nano-CdO have better γ-radiation shielding ability compared to that filled with micro-CdO at the same weight fraction. A relative increase rate of about 16% is obtained with nano-CdO content of 40 wt% at 59.53 keV, which attributed to the higher probability of interaction between γ-rays and nanoparticles. From this study, it can be concluded that nano-CdO has a good performance shielding characteristic than micro-CdO in HDPE based radiation shielding material.
Polymers are often used in medical applications, therefore, some novel polymers and their interactions with photons have been studied. The gamma-ray shielding parameters for Polymethylpentene (PMP), Polybutylene terephthalate (PBT), Polyoxymethylene (POM), Polyvinylidenefluoride (PVDF), and Polychlorotrifluoroethylene (PCTFE) polymers were determined using the Geant4 simulation and discussed in the current work. The mass attenuation coefficients (μ/ρ) were simulated at low and high energies between 0.059 and 1.408 MeV using different radionuclides. The accuracy of the Geant4 simulated results were checked with the XCOM software. The two different methods had good agreement with each other. Exposure buildup factor (EBF) was calculated and discussed in terms of polymers under study and photon energy. Effective atomic number (Zeff) and electron density (Neff) were calculated and analyzed at different energies. Additionally, the half-value layer (HVL) of the polymers was evaluated, and the results of this parameter showed that PCTFE had the highest probability of interaction with gamma photons compared to those of the other tested polymers.
In this work, the γ-ray shielding characteristics of fabricated recycled polyvinyl chloride (rPVC) loaded with micro and nano fillers of PbO and CuO composites were investigated. The PbO/rPVC and CuO/rPVC composites were prepared by changing the percentage of injected materials (PbO and CuO) between 10% and 40% with additions by 10%. Gamma-ray attenuation properties, such as mass attenuation coefficients, linear attenuation coefficients and half-value layer for PbO and CuO-supported polymers were obtained in the energy range between 59.5 and 1408.0 keV using narrow beam transmission geometry. These experiments were carried out by using a HPGe detector and five standard radioactive sources [241Am, 133Ba, 137Cs, 60Co and 152Eu]. Moreover, equivalent atomic numbers and the exposure buildup factor (EBF) values for incident photon energy in the range from 0.015 MeV to 15 MeV were also calculated by Geometric Progression (G-P) method. The experimental results revealed that, the measured values of the linear attenuation coefficients of the PbO/rPVC and CuO/rPVC composites showed their dependence on the type and the concentration of the filler (either PbO or CuO) and also on the incident gamma ray energy. Increasing the filler weight fractions wt.% in the rPVC matrix, increases the linear attenuation coefficients of the composite and the improvement is more significant in case of PbO compared to CuO of the same filler wt.% at the same energy. The results also demonstrated an enhancement in the radiation protection behavior of rPVC composites due to the addition of PbO and CuO fillers as nano-sized particles.
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