The fabrication of different weight percentages of Polycarbonate-Bismuth Oxide composite (PC-Bi2O3), namely 0, 5, 10, 20, 30, 40, and 50 wt%, was done via the mixed-solution method. The dispersion state of the inclusions into the polymeric matrix was studied through XRD and SEM analyses. Also, TGA and DTA analyses were carried out to investigate the thermal properties of the samples. Results showed that increasing the amount of Bi2O3 into the polymer matrix shifted the glass transition temperature of the composites towards the lower temperatures. Then, the amount of mass attenuation coefficients of the samples were measured using a CsI(Tl) detector for different gamma rays of 241Am, 57Co, 99mTc, and 133Ba radioactive sources. It was obtained that increasing the concentration of the Bi2O3 fillers in the polycarbonate matrix resulted in increasing the attenuation coefficients of the composites significantly. The attenuation coefficient was enhanced twenty-three times for 50 wt% composite in 59 keV energy, comparing to the pure polycarbonate.

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Background : In recent years, there has been an increased interest toward non-lead radiation shields consisting of small-sized filler particles doped into polymer matrices. In this paper, we study a new polyvinyl alcohol (PVA)/WO3 composite in the presence of high-energy gamma photons through simulation via the Monte Carlo N-Particle (MCNP) simulation code.Materials and Methods: An MCNP geometry was first designed in the software based on real-life conditions, and the generated geometry was validated by calculating the mass attenuation coefficient and making relative comparisons with standard tables. Using the lattice card in the MCNP input file, WO3 was considered as a filler dispersed in a PVA polymer at sizes of 10 µm and 30 nm with a weight concentration of 50 wt%. By defining 106-photons emitted from point sources corresponding to 662, 778, 964, 1112, 1170, 1130 and 1407 keV energy levels, and the F4 tally used to estimate the cell average flux, the values for mass attenuation coefficient and half-value layer (HVL) were calculated.Results: The results show that PVA/WO3 composite can be considered to shield X and γ-rays in the mentioned energies. However, nano-WO3 has a better ability to shield in comparison with the micro-WO3 fillers. The differences in attenuation changed at different energy levels, ascribed to the dominance of pair production occurrence and photon interactions in the composite, which was in good agreement with previous studies.Conclusion: Our finding showed that the composite can be considered as a lead-free shielding material.

The radiation shielding characteristics of 50 wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WO3 filler particles: micro and nano with sizes of and 50 nm, respectively. The simulation results show that WO3 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.

Abstract In this research work, a two-dimensional model for randomly dispersed single-walled carbon nanotubes (SWCNT) in polymer hosts was used to predict the electrical percolation threshold (EPT) of the resulted composites in different concentrations of CNT. This was performed under a fixed DC voltage for different polymer matrices, such as high-density polyethylene, polymethyl methacrylate, polystyrene, polycarbonate, and polyethylene terephthalate via finite element method (FEM). The predicted EPT values in different composites were validated by experimental results published by other scientists. Results show that the electrical conductivity of the composites was strongly dependent on CNT weight percentages. Also, adding CNTs to the polymer matrix caused a decrease in the tunneling distance for various polymers in composites. Our results show that FEM could capture more details in the prediction of EPT in the nanocomposites.