| Why would you design or
produce a part made of silicone rubber when so many other elastomers are available? A
primary reason is reliability...the ability to perform not only under normal demanding
conditions, but also in the severe extremes of industry, environment, temperature and
voltage. Silicone rubber components have a useful life that is far superior under
conditions that would cause the deterioration of many parts made of typical organic
materials.
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  Silicone rubber has tremendous resistance to temperature extremes. Under
certain conditions, temperatures as high as 600°F (316°C) or as low as -150°F (-101°C)
do not destroy its physical and electrical properties. silicone rubber retains a far
higher tensile strength, ultimate elongation, and tear resistance, and less compression
set at elevated and reduced temperatures than do many organic rubbers. Elasticity is
retained at temperatures as low as -150°F...where parts made from other elastomers would
simply shatter apart when dropped.
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 Silicone rubber, a good non-conductive insulating material,
can be compounded with proper additives to produce a wide range of electrical insulating
properties. Electrical failure occurs when the environment destroys the physical
properties of the elastomer. However, silicone rubber with its excellent resistance to
severe environmental conditions, provides constant electrical insulation properties much
longer than other elastomeric materials. The dielectric breakdown for silicone rubber is
between 400 and 700 volts/mil depending on the compound.
|
 Silicone rubber is superior to other elastomers in its
resistance to compression set (deformation). It shows a marked superiority at both high
and low temperatures. This is particularly important when a silicone rubber part is used
as either a diaphragm, impact absorber, bellows or in other applications where the
component is placed under pressure or is flexed.
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 Silicone rubber is odorless and tasteless. It is very stable
and does not contain sulfur or other acid producing chemicals that generate outgasing. It
also does not cause staining, corrosion or deterioration of other materials. Silicone
rubber will not support the growth of fungus, mold or bacteria.
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 Silicone rubber has an excellent resistance to many
chemicals, fluids and oils commonly encountered in service. Its resistance to chemicals is
particularly useful at temperatures which prevent the use of other materials. silicone
rubber also has excellent resistance to chemicals normally found in th soil.
Fluorosilicone with its unique properties, provides resistance to many fuels, oils and
solvents, including gasoline. Examples of some
chemicals that silicone rubber is resistant to are: |
| ASTM#1 | Citric Acid |
| Heavy Water | Detergent, Water Solution |
| Ethylene Gycol (anti-freeze) | Potassium Chloride |
| Sodium Hydroxide, 3 mole | Methanol |
| Natural Gas | Oxygen, Cold |
| Vegetable Oil | Water Zinc Salts |
 Extensive weathering tests have shown that silicone
rubber substantially resists the deteriorating effects of sunlight, ozone, rain water and
atmospheric gases which cause weathering. Even very dry conditions coupled with harsh
sunlight will not dry out or have an affect on silicone rubber. |
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Silicone rubber is noted for its water resistance.
It has an extremely low degree of water absorption and its mechanical properties show
minimal change, even after long periods of immersion. After four years of undersea
exposure, at a depth of 4,350 feet, silicone rubber samples showed little change in
appearance or properties compared to shelf-aged, control samples. At low or moderate
pressure, silicone rubber is hardly affected by steam.
To some extent, silicone rubber is inherently flame
retardant and most formulations will pass UL 94 HB. Some compounds have approval for use
where flame retardant materials are required and must meet the UL 94V-0 rating.