Surface modification of Bi2O3 and preparation of Bi2O3@Epoxy resin composites: structure, properties and application in γ-ray shielding

gamma-Rays, as high-energy electromagnetic waves, find extensive applications in medical treatment, nuclear facilities, and various other fields. Consequently, there is an urgent demand for radiation shielding materials to safeguard practitioners involved in these fields. In this study, Bi2O3@epoxy composites were fabricated by incorporating Bi2O3 as a filler due to its non-biological and non-toxic nature and its exceptional shielding performance against gamma-rays. To enhance the stable dispersion and interfacial compatibility of Bi2O3 in the epoxy resin, surface modification using a silane coupling agent was initially conducted. The surface modification of Bi2O3 using 2% vinyltrimethoxysilane (A171) was found to significantly enhance the contact angle of the modified Bi2O3 (M-Bi2O3), increasing it from 6 degrees to 139 degrees. Additionally, the settling time in organic media was extended to 18 h, which is approximately 4.5 times longer than that observed for unmodified Bi2O3. The Bi2O3@epoxy composite material was prepared by employing mechanical blending and vacuum defoaming techniques. The resulting composite exhibits a smooth surface devoid of any bubbles, with Bi2O3 uniformly dispersed within the epoxy resin matrix. The tensile strength and flexural strength of the 30% Bi2O3@epoxy composite material are measured to be 57.98 MPa and 91.03 MPa, respectively. Incorporation of Bi2O3 effectively mitigates the thermal motion of epoxy segments, thereby significantly enhancing the thermal stability of the composite materials, rendering them suitable for diverse application scenarios. The composite material exhibits effective shielding against gamma-rays of 662 keV, with a thickness of 15 cm for the EP3 material resulting in a 69% reduction in gamma-ray transmission. The dominant mechanism for shielding gamma-rays with an energy of 662 keV is the photoelectric effect, which is complemented by the Compton effect.