The idea of curing rubber goes back to prehistoric times. The Aztecs, for example, processed rubber by mixing latex with vine juice. However, vulcanization, as we now think of it, was invented by Charles Goodyear (1800-1860) in 1839 (according to his own account). Although Goodyear patented his invention in 1844, he died with huge debts in 1860.
Named after Vulcan, the Roman god of fire, vulcanization is a process of curing rubber using high temperatures and the addition of sulfur. In its natural state, rubber is sticky, deforms when warm, and is brittle when cold. But by linking together the polymer molecules in rubber with bridges of sulfur atoms, it becomes much harder, less sticky, more resistant, and much more durable. As a result, vulcanized rubber has a whole range of useful applications, not least in sealing gaps between moving parts, thereby playing a crucial part in the development of more efficient industrial machines. The ability of vulcanized rubber to absorb stress then revert to its original shape has made it an ideal material for products such as tires, shoes, and rubber bands, while its water-resistant qualities make it perfect for boots, wet weather clothes, and waterproof linings and coatings.
While vulcanization revolutionized manufacturing processes in the nineteenth and twentieth centuries, environmental concerns now focus on how to recycle vulcanized rubber. Some one billion rubber tires, for example, are produced annually but only about 10 percent of waste rubber is reused. Efforts are now being made to find ways to devulcanize rubber without losing all those important properties.
