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There are many types of insulation materials, which can be divided into three categories: gas, liquid, and solid. Commonly used gas insulation materials are air, nitrogen, and sulfur hexafluoride insulated PC films. Liquid insulating materials are mainly of two types: mineral insulating oil, synthetic insulating oil (silicone oil, dodecylbenzene, polyisobutylene, isopropylbiphenyl, diarylethane, etc.). Solid insulation materials can be divided into organic and inorganic types. Organic solid insulation materials include insulating paint, insulating glue, insulating paper, insulating fiber products, plastics, rubber, varnished paint tubes and insulating impregnated fiber products, electrical films, composite products and adhesive tapes, electrical laminates, etc. Inorganic solid insulation materials are mainly mica, glass, ceramics and their products. In contrast, the variety of solid insulation materials is the most important.

Different electrical equipments have different requirements for the performance of insulating materials. The insulation materials used for high-voltage electrical installations such as high-voltage motors and high-voltage cables require high breakdown strength and low dielectric loss. For low-voltage appliances, mechanical strength, elongation at break, and heat resistance grade are the main requirements.

的 Macroscopic properties of insulating materials such as electrical properties, thermal properties, mechanical properties, chemical resistance, weather resistance, and corrosion resistance are closely related to its chemical composition and molecular structure. Inorganic solid insulation materials are mainly composed of silicon, boron and various metal oxides. They are mainly ionic structures. The main characteristics are high heat resistance, working temperature is generally greater than 180 ℃, good stability, resistance to atmospheric aging, and Good chemical properties and long-term aging performance under the action of an electric field; but high brittleness, low impact strength, high pressure resistance and low tensile strength; poor processability. Organic materials are generally polymers with an average molecular weight between 104 and 106, and their heat resistance is usually lower than that of inorganic materials. Materials containing aromatic rings, heterocyclic rings, silicon, titanium, fluorine and other elements have higher heat resistance than ordinary linear polymer materials.

的 The important factors affecting the dielectric properties of insulating materials are the strength of the molecular polarity and the content of polar components. The dielectric constant and dielectric loss of polar materials are higher than non-polar materials, and it is easy to adsorb impurity ions to increase conductivity and reduce their dielectric properties. Therefore, pay attention to cleaning during the manufacture of insulating materials to prevent pollution. Capacitor dielectrics require high dielectric constants to improve their specific characteristics.