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 like matrix crazing, can account for a large fraction of the increase in energy absorption of a toughened polymer. Evidence of shear yielding in a toughened polymer can be seen where there is "necking, drawing or orientation hardening." Shear yielding will result if rubber particles act as stress concentrators and initiate volume-expansion through crazing, debonding and cavitation, to halt the formation of cracks. Overlapping stress fields from one particle to its neighbor will contribute to a growing shear-yielding region. The closer the particles are the more overlap and the larger shear-yielding region. Shear yielding is an energy absorbing process in