Sulfur vulcanization are merely the additives used for vulcanisation and that other compounds may also be added to the rubber such as fillers or polymer stabilizers. Ordinary sulfur (octasulfur) is rarely used despite its low cost. Because of the low melting point of S vs the cure temperatures, attempted vulcanization with ordinary results in sulfur bloom. Instead, various forms of polymeric sulfur are used instead. It is also possible to replace sulfur with other sulfur-donating compounds, for example accelerators bearing disulphide groups, in what is often termed 'efficient vulcanization' (EV). Disulfur dichloride may also be used for 'cold vulcanization'. Under normal circumstances,
Rubber toughening and the energy to break rubber particles could account for the increased energy absorption of toughened polymers. This theory was limited, only accounting for a small fraction of the observed increase in fracture energy. The matrix crazing theory focuses on explaining the toughening effects of crazing. Crazes start at the equator where principal strain is highest, propagate perpendicular to the stress, and end when they meet another particle. Crazes with perpendicular fibrils can eventually become a crack if the fibrils break. The volume expansion associated with small crazes distributed through a large volume compared to the small volume of a