Rubber

Natural rubber is an elastic polymer, mostly polyisoprene, coagulated from the milky latex of the Para rubber tree, Hevea brasiliensis, native to the Amazon basin and used by Mesoamerican peoples for waterproof cloth and bouncing balls centuries before European contact. As imported to nineteenth-century Europe and North America, raw latex rubber turned brittle in cold weather and sticky in heat, which limited it to a novelty until Charles Goodyear discovered, by accident in 1839, that heating rubber together with sulfur cross-links its polymer chains into a durable, elastic material stable across a wide temperature range, a process he named vulcanization after the Roman god of fire. Vulcanized natural rubber became the material of the pneumatic tire and, as tire demand and wartime shortages of natural supply grew through the twentieth century, drove the development of synthetic rubbers such as styrene-butadiene, which today supply most of world rubber consumption.