Natural rubber is derived from latex, a milk-like serum, which comes from the Hevea Brasiliensis tree. Two early problems with natural rubber were its stickiness when exposed to heat and brittleness when exposed to cold. In 1839, Goodyear developed the process of using sulfur to cross-link polymer chains, known as vulcanization. The “vulcanized” product had better resistive properties to extreme temperature changes and thus allowed the development of the rubber market of today.
The basic structural building block of natural rubber is isoprene (2-methyl-1,3-butadiene). When deciding on a suitable monomer for the synthetic version, researchers searched for a diene (diolefin) with similar characteristics to isoprene. The structure of butadiene was a close match to isoprene, and its subsequent homopolymerization and copolymerization with styrene and acrylonitrile created a new class of compounds with various useful properties.
