The electrical insulation of rubber is related to the molecular structure of rubber. Generally, non-polar rubbers, such as natural rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, and silicone rubber, have better electrical insulation. Among them, silicone rubber, ethylene propylene rubber, and butyl rubber have better high-voltage electrical insulation properties, and also have better heat resistance, ozone resistance, and weather resistance. They are commonly used electrical insulating rubbers. Natural rubber, styrene-butadiene rubber, butadiene rubber and their concomitant rubbers can only be used for medium and low pressure products. They not only have poor heat resistance and ozone aging resistance, but also the residues such as emulsifiers added in the synthesis process of styrene-butadiene rubber and cis-butadiene rubber are electrolytes, especially water-soluble ions have a great influence on electrical insulation, so When these rubbers are used as electrical insulating rubbers, their purity should be strictly controlled.

Polar rubber is not suitable for electrical insulating rubber, especially for high-voltage electrical insulating products, but chloroprene rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, and chlorobutyl rubber have good weathering resistance and Oil resistance, so it can be used for outdoor electrical insulation products with low insulation degree. Fluorine rubber, chloroether rubber, nitrile rubber, and nitrile rubber/polyvinyl chloride blends can be used as heat-resistant, oil-resistant and flame-retardant electrical insulating rubbers, respectively.

Under normal circumstances, carbon black is not used in electrical insulating rubber, because when the amount of carbon black is large, it is easy to form conductive channels, especially carbon black with small particle size and large specific surface area, which significantly reduces electrical insulation; commonly used in electrical insulating rubber The fillers are clay, talc, calcium carbonate, mica powder, silica and other inorganic fillers; The insulation performance of peroxide vulcanization is better than that of sulfur and effective vulcanization systems; polar materials are less or not added to the compounding system; the oil should be selected as non-polar macromolecular oil as possible, such as natural and butyl benzene, transformer oil, etc.