NATURAL RUBBER
The outstanding strength of natural rubber has maintained its position as the preferred material in many engineering applications. It has a long fatigue life and high strength even without reinforcing fillers. Other than for thin sections it can be used to approximately 100°C, and sometimes above. It can maintain flexibility down to - 60°C if compounded for this purpose. Its chief disadvantage is its poor oil resistance and its lack of resistance to oxygen and ozone. It can be used when high elasticity and high mechanical properties are important.
STYRENE - BUTADIENE RUBBER
This is the highest volume general purpose synthetic rubber. It is weak unless reinforcing fillers are incorporated with suitable fillers. It is a strong rubber although not approaching natural rubber. Otherwise it has similar chemical and physical properties to natural rubber, with generally better abrasion resistance but poorer fatigue resistance. It is also resistant to glycol based brake oils, acids, bases and alcohol. The operation temperature range is between - 50°C and + 100°C.
ETHYLENE - PROPYLENE RUBBER
Probably the most water resistant rubber available and this resistance is maintained to high temperatures. Has excellent resistance to atmospheric ageing, oxygen and ozone up to about 150°C. It has good resistance to most water-based chemicals and to hydraulic oils. However it has very poor resistance to mineral oils and di-ester based lubricants, it can be operated between - 50°C and + 100°C and can be used for automotive brake fluids generally.
CHLOROPRENE RUBBER
This rubber has a generally good balance of mechanical properties and fatigue resistance second only to natural rubber, but with superior chemical, oil and heat resistance. It is widely used in general engineering applications. It has good ozone resistance. It is used between - 40°C and + 100°C. It is suitable for use with mineral oils and greases and dilute acids, but is unsuitable in contact with fuels.
NITRILE BUTADIENE RUBBER
Nitrile butadiene rubber is the mostly preferred and a general purpose material operating between - 40°C and + 100°C in the seal technology. At temperatures up to 100°C, or with special compounding up to 120°C, nitrile rubber provides an economic material having a high resistance to aliphatic hydrocarbon oils and fuels. The higher the acrylonitrile content, the higher the oil resistance but the poorer is low temperature flexibility. It has high resilience and high wear resistance but only moderate strength. It can generally be used down to about - 30°C, but special grades can operate at lower temperatures.
SILICONE RUBBER
The outstanding property of these materials is their very wide temperature range. Typically the range is - 60°C to + 200°C and above. They don't have very good physical properties, but the properties they do have are retained to high temperatures. It is used extensively in crankshaft seals, silicone rubber exhibits high endurance to oxygen and ozone, but low resistance to EP (extreme pressure) type oils and to tear.
URETHANE RUBBER
These materials have high tear strength and good wear resistance. Operating temperature range is between - 25°C and + 100°C. They resist hydrocarbon fuels and mineral oils but some grades hydrolyses in hot water. They are one of the best elastomers for abrasion resistance and are therefore used in reciprocating seals and high pressure applications.
FLUOROCARBON RUBBER
These elastomers are designed for very high temperature operation. They are used between the temperatures - 20°C and + 250°C. They have outstanding resistance to chemical attack by oxidation, by acids and by fuels. They have limited resistance to steam, hot water, methanol and other highly polar fluids. It is recommended for crankshaft seals at high temperature and high revolutions. But they are expensive materials.
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