Rubbers are flexible long chain polymers that can be stretched easily to several times their unscratched length and rapidly return to their original dimensions.
What is a rubber?
The term rubber includes both natural rubber and synthetic rubber. Rubbers are flexible long chain polymers that can be stretched easily to several times their unscratched length and which rapidly return to their original dimensions when the applied stress is released.
Rubbers are cross-linked (vulcanized), but have a low crosslink density. The cross-link is the key to the elastic, or rubbery, properties of these materials. The elasticity provides resiliency in sealing applications. At temperatures up to about 100°C
Properties of silicone rubbers (Q)
Silicone rubbers have outstanding properties, such as low compression set in a wide range of temperatures (from-60°C to 200°C in air), excellent electrical insulation and are non-toxic.
Silicone rubbers are resistant to water, some acids and oxidizing chemicals. However, concentrated acids, alkalines, and solvents should not be used with silicone rubbers. In general, these types of rubber have poor resistance to oil and fuel. However, the resistance of FMQ silicone rubber to oil and fuel is better than that of the silicone rubber types MQ, VMQ, and PMQ.
Perfluoroelastomers have very high chemical resistance, almost comparable to that of PTFE (polytetrafluorethylene, e.g. TeflonR). They can be used up to high temperatures, but their disadvantages are difficult processing, very high cost and limited use at low temperatures.