Chemical and Physical Properties

Chemical and Physical Properties 

Pure crude rubber is a white or colorless hydrocarbon. The simplest unit of rubber is isoprene, which has the chemical formula C5H8. At the temperature of liquid air, which is about -195 C (about -319 F), crude rubber is a hard, transparent solid; from 0 to 10 C (32 to 50 F) it is brittle and opaque, and above 20 C (68 F) it becomes soft, resilient, and translucent. When rubber is mechanically kneaded, or is heated above 50 C (122 F), it becomes plastic and sticky; above 200 C (392 F) it decomposes.

Crude rubber is insoluble in water, alkali, and weak acid; it is soluble in benzene, gasoline, chlorinated hydrocarbons, and carbon disulfide. It is oxidized readily by chemical oxidizing agents, and slowly by atmospheric oxygen
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