Remainder of the juice of rubber tree (Hevea brusiliensis) after evaporation. Rubber, chemically composed of polyisopyrene, crosslinks with sulfur compounds forming a high resistance elastomer. Process of crosslinking with sulfur compounds is called vulcanization, and rubber that undergoes vulcanization is called vulcanized rubber.
Hard thermoplastic resin that is obtained from reaction of natural rubber with chloride, containing approximately 65% chloride and that is soluble in aromatic solvents. It has superior chemical resistance and water resistance. There are also some commercial products obtained from chlorination of synthetic rubber.