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The serious damage caused to 3D braided carbon fiber (CF)/epoxy (EP) composites in high-energy irradiation environments is a pressing research topic that has not yet been reported. This study analyzed the γ-irradiation multi-scale damage of the matrix, interfaces, and near-interface regions in 3D braided CF/EP composites with three different braiding angles (18°, 28°, 38°) at atomic, microscopic, and macroscopic scales. The molecular structure and atomic charge information alterations of epoxy matrix were characterized using soft X-ray absorption spectroscopy (sXAS). When the irradiation dose reached 1000 KGy, the compressive strength of composites decreased by 20.88 %, 18.07 %, and 16.60 %, respectively, with an increase in the braiding angle. Micro-CT observation, along with statistical computing, confirmed that irradiation causes interface damage and increases the defect volume of 3D braided composites. Nanoindentation was used to compare the modulus of carbon fiber, interface, near-interface regions and matrix in irradiated composites and the function of CF/resin interface as an irradiation defect capture site in the irradiation resistance of resin-matrix composites has been newly established. In addition, the mechanism behind the effect of braiding angle on macroscopic properties was also analyzed. [Display omitted] • The braided structures exhibited varying responses to irradiation, with 3D-38° showing the highest performance retention. • Soft X-ray absorption spectrometry was developed to characterize the valence changes of oxygen and carbon in irradiated resin. • Interface as an irradiation defect capture site consumes most of the energy and reduces the damage of resin near the interface. [ABSTRACT FROM AUTHOR]

• Modified metal-organic framwork are applied to improve the radiation resistance of epoxy resins and investigate the anti irradiation mechanism of metal-organic framework. • UIO-66-OH nanoparticles can effectively improve the tensile modulus and thermal stability of epoxy resin. • 88.7% reduction in free radical concentration of UIO-66-OH / EP composite compared to epoxy resin. Understanding the degradation mechanism of epoxy resin under irradiation and enhancing the radiation resistance of epoxy resin are of great significance for its application in aerospace and nuclear industries. In this study, we investigated the radiation resistance of epoxy reinforced by UIO-66-OH metal-organic framework. Outstanding radiation resistance was achieved by using UIO-66-OH nanoparticles as radical scavengers to retard epoxy degradation. The introduction of UIO-66-OH reduces the content of free radicals generated after irradiation by 88.17%. UIO-66-OH also improves the mechanical and thermal properties of epoxy before and after irradiation. The scavenging radicals mechanism of hydrogen atom transfer of UIO-66-OH is more dominant than that of graphene oxide and carbon nanotubes. The radiation resistance of UIO-66-OH nanoparticles is related to hydroxyl functionalization and porous structure. This work provides a new idea and method for improving the stability of epoxy resin under gamma ray radiation. [ABSTRACT FROM AUTHOR]