The Use Of Silicone
🕙 2023-08-04 👆
Silicone rubber polymer molecule is a chain structure formed by Si-O (silicon-oxygen) bond, which is mainly composed of linear polysiloxane with high molar mass. Since Si-O-Si bond is the basic bond type of its composition, silicon atoms mainly connect methyl groups, introduce a very small amount of unsaturated groups on the side chain, the intermolecular force is small, the molecule is spiral structure, methyl groups are arranged outwardly and can rotate freely, making silicone rubber has better heat resistance, electrical insulation, chemical stability and so on than other ordinary rubber. Typical silicone rubber, that is, polydiformaldehyde siloxane, has a helical molecular configuration, the intermolecular force is small, so it has good resilience, and the formaldehyde group pointing to the outside of the helix can be freely rotated, so that the silicone rubber has unique surface properties, such as hydrophobicity and surface anti-viscosity. The following table lists the main characteristics and uses of silicone rubber.
A. Heat resistance: silicone rubber has much better heat resistance than ordinary rubber products, and can be used almost forever at 150 degrees without performance changes; It can be used continuously for 10,000 hours at 200 degrees; It can also be used for a period of time at 350 degrees. Widely used in situations requiring heat resistance: hot water bottle sealing ring pressure cooker ring heat handle cold resistance: ordinary rubber delay is -20 degrees ~-30 degrees, that is, silicone rubber still has good elasticity when it is -60 degrees ~-70 degrees, and some special formula of silicone rubber can also withstand extremely low temperatures.
B. weather resistance: ordinary rubber rapidly degrades under the action of ozone generated by corona discharge, while silicone rubber is not affected by ozone. In addition, under ultraviolet light and other climatic conditions for a long time, its physical properties only change slightly.
C. electrical properties: silicone rubber has a high resistivity and its resistance remains stable over a wide range of temperatures and frequencies. At the same time, silicone rubber has good resistance to high voltage corona discharge and arc discharge.
D. electrical conductivity: when adding conductive filler (such as carbon black), silicone rubber has a keyboard conductive contact point
E. thermal conductivity: When adding some thermal conductivity filler, silicone rubber has thermal conductivity heat sink thermal sealing pad photocopier, fax machine thermal roller
F. radiation: containing phenyl silicone rubber radiation resistance greatly improved electrical insulation cable nuclear power plant connectors
G. flame retardant: silicone rubber itself is flammable, but when adding a small amount of flame retardant agent, it has flame retardant and self-extinguishing; And because silicone rubber does not contain organic halides, it does not smoke or emit toxic gas when burning.
H.permeability: silicone rubber film than ordinary rubber and plastic waxing film has better permeability. Another feature is that it has a strong selectivity for different air permeability.
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