Preparation process and insulation performance analysis of new optical cable sheath

Polyethylene is often used as the outer protective layer of optical cables due to its excellent dielectric, corrosion resistance, and mechanical properties. However, when facing high-voltage optical cable lines, its insulation ability is slightly insufficient. Therefore, a new type of optical cable sheath has been studied and prepared. This sheath is suitable for optical cable systems with voltage levels of 10 kV and below, and can meet the insulation and protection requirements in power communication scenarios. Firstly, different forms of magnesium oxide were prepared by hydrothermal and redox methods, and added to a polyethylene solution. The magnesium oxide/polyethylene composite film was prepared by a solution casting process with thermal crosslinking at 180°C for 15 min. To further improve the performance of composite films, a new type of optical cable sheath material, magnesium oxide/polyethylene composite film, was prepared by combining high thermal conductivity alumina with fibrous magnesium oxide/polyethylene. The results showed that when the amount of fibrous magnesium oxide in different forms of magnesium oxide/polyethylene composite films was 1.5 phr, the breakdown strength could reach 468 kV/mm, which was 26.49% higher than that of pure polyethylene, and the dielectric capacity increased by 5%. The direct current breakdown strength of the alumina/magnesium oxide/polyethylene composite film was 518 kV/mm, which was 14.11% higher than that of the magnesium oxide/polyethylene composite film. The above data indicated that the insulation performance of the modified optical cable sheath was greatly improved, which can adapt to higher voltage optical cable protection. The research provides important references for the design and optimization of new optical cable sheath materials, as well as new ideas and methods for material research in related application fields.