TYPES OF SYNTHETIC RUBBER

Only one synthetic rubber has been developed as a general-purpose replacement for natural rubber. This rubber is composed principally of about one part of styrene and about three parts of butadiene and is known as styrene-butadiene rubber, or SBR; it was formerly known as Buna-S -and GRS.

No synthetic rubber has the chemical composition or all the properties of natural rubber.

However, some special-purpose synthetic rubbers have been developed which have particular properties that are superior to natural rubber for specific purposes. The four principal special-purpose synthetic rubbers are nitrile, neoprene, butyl, and thiokol.

Thiokol is used where high resistance to oils and chemicals, which attack natural rubber, are desired and where its unpleasant odor is not objectionable.

Neoprene have high resistance to mineral oils, heat, oxidation, ozone, sunlight, and burning.

Nitrile rubber competes with neoprene where resistance to oil and gasoline is desired. Almost all nitrile rubber produced during World War II was used in self-sealing fuel tanks, gaskets, cable covers, and similar equipment for military aircraft.

Butyl rubber is markedly superior to natural rubber in air retention and is used for inner tubes.

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