Sulfur vulcanization a reaction with low levels of unsaturated organic linkers (e.g. 1,3‐diisopropenylbenzene). This process is called inverse vulcanisation and produces polymers where sulfur is the main component. It is not currently of commercial importance but had been investigated as a means of producing polymers for lithium–sulfur batterys and for creating water filters with a high affinity for mercury. The curing of rubber has been carried out since prehistoric times. The name of the first major civilization in Guatemala and Mexico, the Olmec, means 'rubber people' in the Aztec language. Ancient Mesoamericans, spanning from ancient Olmecs to Aztecs, extracted latex from "Castilla
Foam rubber Foam rubber Foam rubber (also known as cellular, sponge, or expanded rubber) refers to rubber that has been manufactured with a foaming agent to create an air-filled matrix structure. Commercial foam rubbers are generally made of either polyurethane or natural latex. Latex foam rubber, used in mattresses, is well known for its endurance. Polyurethane is a thermosetting polymer that comes from combination of Methyl di-isocyanate and polyethylene and some other chemical additives. Foam rubber was first produced in 1929 by Dunlop Rubber researcher chemists E. A. Murphy and Eric Owen using whipped latex. In 1937 isocyanate based materials were first