Polymer matrix composites (PMCs) often undergo aging as a result of ultraviolet (UV) radiation, which significantly impacts their performance and durability. This paper investigated the alterations in the microstructure and macroscopic properties of epoxy resin and its composite used in overhead wires during UV aging. Furthermore, the mechanism of UV aging for both resin and composite was revealed. The results showed that UV aging predominantly affected the properties of the surface layer resin. UV aging can induce molecular chain scission, which leads to resin weight change, color deepening, microcrack formation, a decline in mechanical properties, and other performance degradation behaviors under the combined action of many factors. With the increase in aging time, the weight change rate and hardness of the resin increased first and then decreased, while the mechanical properties of the composite decreased rapidly first and gradually tended to be constant. The bending strength and impact strength of the composite decreased by 6.0% and 12.8%, respectively, compared with the initial values. The purpose of this study is to comprehensively understand the UV aging behaviors of epoxy resins and their composites employed in overhead wires, and it also provides essential data for advancing the utilization and durability of epoxy resins and composites across aerospace, marine, and other outdoor applications.
Keywords: environmental degradation; mechanical properties; polymer matrix composites (PMCs); ultraviolet irradiation.