Background
Natural rubber is an elastomer, also known as tree gum, India rubber, and caoutchouc, which comes from the rubber tree in tropical regions. Christopher Columbus was the one of the first Europeans to bring news of this odd substance back to Europe, but he was not the only one to encounter this substance. In fact around 1736, a French astronomer recalled how Indians used rubber to waterproof shoes and cloaks. He then brought several samples of rubber back to France. Rubber was then used as an eraser by Joseph Priestley in England. It wasn’t until the 1800s that practical uses of rubber were known and the demand for rubber began. The first factory for rubber products (suspenders (US) or braces (UK)) was in Paris, France, in the year 1803. However, the material still had disadvantages: at room temperature, it was sticky. At higher temperatures, the rubber became softer and stickier, while at lower temperatures it became hard and rigid.
It was the South American Indians who first discovered rubber; sometime dating back to 1600BC. They had first used rubber as a ball in a game they called Tlachtlic. Thus, it was in the Amazon rainforest that rubber extraction developed, using the rubber tree (Hevea brasiliensis), a member of the Euphorbiaceae family.
A white liquid called latex is extracted from the stem of the rubber tree, which contains on average 35% hydrocarbons, in particular 2-methylbuta-1,3-diene (C5H8), commercially known as isoprene, the monomer of rubber.
Latex is a practically neutral substance, with a pH of 7.0 to 7.2. However, when it is exposed to the air for 12 to 24 hours, its pH falls to 5.0 and it spontaneously coagulates to form the polymer rubber, represented by (C5H8)n, where "n" is of the order of 10,000 and gives a molecular mass of 600,000 to 950,000 g/mol.
Rubber produced in this fashion has disadvantages. For example, exposure to air causes it to mix with various materials, which is perceptible and can cause rot, as well as a temperature-dependent stickiness. With an industrial treatment, the impurities are removed and the rubber is exposed to a process of vulcanization, eliminating the undesirable qualities. It acquires superior mechanical properties, loses its sticky character, and becomes stable and resistant to solvents and variations in temperature.
Read more about this topic: Rubber Boom
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