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 and crazing interaction theory, and more recently those including the effects of critical ligament thickness, critical plastic area, voiding and cavitation, damage competition and others. In 1956, the microcrack theory became the first to explain the toughening effect of a dispersed rubber phase in a polymer. Two key observations that went into the initial theory and subsequent expansion were as follows: (1) microcracks form voids over which styrene-butadiene copolymer fibrils form to prevent propagation, and (2) energy stored during elongation of toughened epoxies is released upon breaking of rubber particles. The theory concluded that the combined energy to initiate microcracks