Silicone rubber is a kind of polymer elastic material with inorganic and organic nature. Its backbone is composed of alternating silicon and oxygen atoms form (- Si - O - Si), the side chain is hydrocarbon or hydrocarbon substituted organic groups connected with silicon atoms, such groups can be methyl, unsaturated vinyl (mole fraction is generally not more than 01005) or other organic groups, this low unsaturation molecular structure makes the silicon rubber has excellent heat aging resistance, weathering resistance and resistance to ultraviolet and ozone erosion. The structural characteristics such as the flexibility of the molecular chain is large and the interaction force between the molecular chain is weak make the vulcanized rubber soft and elastic, but poor physical properties.
Here are the main features of silicone rubber:
Heat resistance: silicone rubber has good heat resistance compared to ordinary rubber, it can be below 150 degrees almost always use without performance change; can be used continuously for 10000 hours at 200 degrees; can also be used for a period of time at 350 degrees. It is widely used in occasions requiring heat, such as sealing ring of hot water bottle.
Cold resistance: the general rubber is delayed for -20 degrees ~-30 degrees, that is, silicone rubber of -60 degrees ~-70 degrees still have better flexibility, some special formula of silicone rubber can withstand extremely low temperature.
Electrical properties: silicone rubber with high resistivity, and it resistance remained stable in a wide range of temperature and frequency. At the same time, silicone rubber has good resistance to high voltage corona discharge and arc discharge.
Weather resistance: ordinary rubber rapid degradation under ozone produced by corona discharge, while silicone rubber is not affected by ozone effect. And its physical properties have only minor changes at long time in the ultraviolet and other climatic conditions.
Conductivity: when adding conductive fillers (carbon black), silicone rubber has keyboard conductive contact point.
Thermal conductivity: when adding some conductive filler, silicone rubber has the thermal conductivity.
Radiation: the radiation resistant greatly improve if silicone rubber contains phenyl.
Flame retardant: silicone rubber itself is flammable, but it has a flame-retardant and self extinguishing when adding a small amount of anti burning agent; and because the silicone rubber containing no organic halides, thus the burning without smoke or emit toxic gases.
Permeability: silicone rubber film is better than ordinary rubber and plastic film. And it has a strong selectivity to different air permeability.
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