The main component of natural rubber is cis-1,4-polyisoprene, which is a typical non-polar rubber with good electrical insulation properties and can be used to produce various medium and low voltage insulation products such as insulating rubber sheets. When using natural rubber to produce electrical insulation products, rubber product manufacturers need to correctly select rubber additives to further improve the electrical insulation of the rubber. Comprehensively consider the influence of various compounding agents on other properties of the rubber compound, and avoid the use of compounding agents and compounding systems that affect the insulating properties of natural rubber vulcanizates as much as possible.
1. Compounding agent for vulcanization system
Since different types of cross-linked bonds will produce different dipole moments in the vulcanizate, the vulcanization system has an important influence on the electrical insulation properties of natural rubber insulation products.
When sulfur is used for vulcanization, the initial conductivity of natural rubber vulcanized rubber increases with the increase of the amount of sulfur. When the amount of sulfur is increased to 18 parts, the conductivity has a maximum value. After the amount of sulfur is continuously increased, the conductivity of 2YLYY42 drops sharply. The dielectric constant and dielectric loss of natural rubber vulcanized rubber will increase as the amount of sulfur increases. When the amount of sulfur reaches 10-14 parts, the maximum value will appear. If the amount of sulfur continues to increase, the above two indexes will decrease. .
Theoretically, a large amount of sulfur in the formulation of natural rubber products can further improve the electrical insulation of natural rubber vulcanizate, but the increase in the amount of sulfur will cause the heat resistance of the vulcanized rubber to decrease, so it is not appropriate to increase the amount of sulfur to improve the electrical insulation of natural rubber. The electrical insulation of the product. In actual production, considering the insulation and heat resistance of natural rubber vulcanized rubber, it is recommended to use a low-sulfur compounding system or a sulfur-free vulcanizing system.
2. Reinforcing system compounding agent
The amount of compounding agent in the reinforcement and filling system of natural rubber products is second only to raw rubber, which has a greater impact on the electrical insulation properties of natural rubber vulcanizates. In actual production, calcium carbonate, talcum powder, ordinary clay, etc. are commonly used as fillers in natural rubber low-voltage electrical insulation products. Carbon black will reduce the electrical insulation performance of natural rubber vulcanized rubber during use, especially carbon black with high structure and large surface area. Therefore, it is not recommended to use carbon black for reinforcement in the formulation of natural rubber electrical insulation products. If necessary, use appropriate amount of particles. Medium particle thermal black or fine particle thermal black with large diameter and low structure.
It should be noted that rubber fillers with strong water absorption and high moisture content will reduce the electrical insulation performance of natural rubber vulcanizates. Pay special attention to the water absorption and moisture content of the fillers.
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