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

Abstract

γ-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 γ-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° to 139°. 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 γ-rays of 662 keV, with a thickness of 15 cm for the EP3 material resulting in a 69% reduction in γ-ray transmission. The dominant mechanism for shielding γ-rays with an energy of 662 keV is the photoelectric effect, which is complemented by the Compton effect.