Silicone rubber is used as an antipollution flashover material in outdoor insulation, which is susceptible to aging and has a shorter service life than other candidates. Microcracks are a common aging phenomenon that are difficult to be detected and repaired. The microcapsule self‐healing technology can be used to repair microcracks and extend the service life of silicone rubber. This study considers hydrogen silicone oil as a representative of the polydimethylsiloxane healing agent system. Poly(urea–formaldehyde) microcapsules containing the hydrogen silicone oil are synthesized by in situ polymerization. The effects of the emulsifier concentration, initial pH value, initial ratio of the core–shell material, and sodium chloride (NaCl) concentration on the synthesis are investigated. Accordingly, the properties of the microcapsules before and after long‐term storage are analyzed. The results demonstrate that microcapsules synthesized using poly(ethylene‐alt‐maleic anhydride) (EMA)+ polyvinyl alcohol (PVA) as the emulsifier have satisfactory morphology and performance, where the best synthesis conditions are 0.13 wt% EMA, 0.05 wt% PVA, initial ratio of the core–shell material of 1.5:1–2.0:1, initial pH value of 3.5–4.0, and 2 wt% NaCl. In long‐term storage, the core material is well protected by the shell material. The synthesized microcapsule can serve as a material in the self‐healing system of silicone rubber.
Compared with the high-temperature vulcanized silicone rubber (HTVSR) insulator, the alicyclic epoxy resin insulator has higher hardness and better bonding between the core and the sheath. This makes the latter very promising in the coastal area of Southern China. Outdoor insulators are often subjected to high intensity of ultraviolet (UV)-A radiation. The influence of UV-A radiation is significant for alicyclic epoxy resin insulators. To help address the concern, the surface of two kinds of samples, namely the alicyclic epoxy resin insulator and HTVSR insulator, with UV-A aging time was characterized by tests of scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The operation properties (mechanical properties, hydrophobicity) for outdoor insulators were also analyzed. It was found that the appearance color of the alicyclic epoxy resin has changed greatly, and there is a certain degree of fading. The mechanical properties of the alicyclic epoxy resin are maintained well and, the hydrophobicity decreases gradually. For silicone rubber, the appearance color change of silicone rubber is smaller, and the mechanical properties of silicone rubber decreased greatly. In addition, although the hydrophobicity of silicone rubber decreased gradually, it is still better than that of alicyclic epoxy resin. Both materials have broken chemical bonds, but the degree is relatively light, which meets the requirements of insulators for outdoor operation.
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