Classification and performance There are many types of insulating materials, which can be divided into three categories: gas, liquid and solid. Commonly used gas insulating materials are air, nitrogen, sulfur hexafluoride, etc. Liquid insulating materials mainly include mineral insulating oil and synthetic insulating oil (silicone oil, dodecylbenzene, polyisobutylene, isopropyl biphenyl, diarylethane, etc.). Solid insulating materials can be divided into two categories: organic and inorganic. Organic solid insulating materials include insulating paint, insulating glue, insulating paper, insulating fiber products, plastics, rubber, varnished varnished pipes and insulating impregnated fiber products, electrical films, composite products and adhesive tapes, electrical laminates, etc. Inorganic solid insulating materials mainly include mica, glass, ceramics and their products. In contrast, solid insulating materials are diverse and most important.
Different electrical equipment has different requirements for the performance of insulating materials. Insulation materials for high-voltage electrical devices such as high-voltage motors and high-voltage cables are required to have high breakdown strength and low dielectric loss. For low-voltage electrical appliances, the main requirements are mechanical strength, elongation at break, and heat resistance grade.
The macroscopic properties of insulating materials such as electrical properties, thermal properties, mechanical properties, chemical resistance, weather resistance, corrosion resistance and other properties are closely related to its chemical composition and molecular structure. Inorganic solid insulating material is mainly composed of silicon, boron and various metal oxides, mainly ionic structure, the main feature is high heat resistance, working temperature is generally greater than 180 ℃, good stability, resistance to atmospheric aging, resistance 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 craftsmanship. Organic materials are generally polymers with an average molecular weight between 10 and 10, and their heat resistance is usually lower than that of inorganic materials. The heat resistance of materials containing aromatic rings, heterocycles and elements such as silicon, titanium, and fluorine is higher than that of general linear polymer materials.
The important factors affecting the dielectric properties of insulating materials are the strength of molecular polarity and the content of polar components. The dielectric constant and dielectric loss of metallized film Suppliers polar materials are higher than those of non-polar materials, and it is easy to adsorb impurity ions to increase conductivity and reduce its dielectric properties. Therefore, attention should be paid to cleanliness in the manufacturing process of insulating materials to prevent pollution. Dielectrics for capacitors require high dielectric constants to improve their specific characteristics.
Plastics can be divided into two categories: thermosetting and thermoplastic. The former cannot be reshaped and used, and the latter can be repeatedly produced. There are basically two types of structures of plastic polymers: the first is linear structure, and the polymer compound with this structure is called linear polymer compound; the second is the body structure, the polymer compound with this structure It is called a bulk polymer compound. Some polymers have branched chains, called branched polymers, which belong to a linear structure. Although some polymers have cross-links between molecules, they are less cross-linked, which is called a network structure and belongs to a body structure. Two different structures, showing two opposite properties. High polymer with linear structure (including branched structure) has the characteristics of elasticity and plasticity due to the existence of independent molecules, it can be dissolved in solvent, can be melted when heated, and has the characteristics of less hardness and brittleness. Since there are no independent macromolecules, the body-shaped polymer has no elasticity and plasticity, cannot dissolve and melt, but can only swell, and has high hardness and brittleness. Plastics have two structures of polymers, thermoplastics made of linear polymers, and thermosetting plastics made of bulk polymers.