Green preparation and evaluation of bentonite supported Bi₂O₃/polyester nanocomposites as gamma radiation shielding...

In this work, a novel mixture of Bi₂O₃-NPs and bentonite was prepared using green synthesis method using olive leaves extract where Bi₂O₃-NPs were formed and loaded on the surface of bentonite layers to get homogeneous mixing between Bi₂O₃-NPs and bentonite. The successful preparation of this mixture was confirmed using TEM, IR and XRD. After that, unsaturated polyester nanocomposites with varying ratios (1, 5, 10, and 20 wt%) were prepared using this synthesized mixture. These composites were evaluated as shielding materials against gamma radiation, since different shielding parameters were measured at different energies (59, 661, (1173 and 1333 keV) from Am-241, Cs-137, and Co-60, respectively. Also, the thermal and mechanical properties were measured, where the 20 wt% sample only exhibits 50% weight loss after 402 °C, as opposed to 357 °C for pure unsaturated polyester. On the other hand, results of compressive strength showed slight enhancement with addition of bentonite compared to only Bi₂O₃ nanocomposites. The results showed the improvement of shielding properties with increase of filler ratio, where the 20 wt% nanocomposite sample has highest LAC values among all samples where it has LAC values of 1.133, 0.126, 0.091, and 0.090 cm^-1 at 59, 661, 1173, and 1333 keV, respectively. This demonstrates the importance of using these nanocomposites as radiation shields against low-energy photons, since it can achieve a shielding efficiency of 90% at 59keV.