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
Rubber toughening of waste rubber from car tires has sparked interest in finding uses for this discarded rubber. The rubber can be turned into a fine powder, which can then be used as a toughening agent for polystyrene. However, poor miscibility between the waste rubber and polystyrene will weaken the material. This problem requires the use of a compatibilizer (see "compatibilization") in order to reduce interfacial tension and ultimately make rubber toughening of polystyrene effective. A polystyrene/styrene-butadiene copolymer acts to increase the adhesion between the dispersed and continuous phases. Rubber toughening Rubber toughening is a process in which rubber nanoparticles are interspersed