Bismaleimides, vulcanization

Peroxides decompose when heated to produce active free radicals which in turn react with the mbber to produce cross-links. The rate of peroxide cure is controlled by temperature and selection of the specific peroxide, based on half-life considerations (see Initiators, free-radical Peroxy compounds, organic). Although some chemicals, such as bismaleimides, triallyl isocyanurate, and diallyl phthalate, act as coagents in peroxide cures, they are not vulcanization accelerators. Instead they act to improve cross-link efficiency (cross-linking vs scission), but not rate of cross-link formation. 

One of the curing characteristics that we would like to control is reversion, which can occur in compounds containing natural rubber. There is more than one approach to reducing the amount of reversion. We can use sulfur donors or increase the ratio of accelerator concentration to sulfur concentration, or we could carry out the vulcanization at a reduced temperature for a longer period. However, these approaches give rise to effects that will have to be compensated. Another approach is use of additives such as certain bisimides, e.g., N,N -m-phenylene-biscitraconimide and N,N -/m-phenylene-bismaleimides (Datta et al., 1997, 1998 Datta and Ivan, 1995) or trialkoxysilylalkylpoly-sulfides such as bis-(3-triethoxisilylpropyl)-tetrasulflde (Tan and Wolff, 1985). 

VII. Vulcanization by Phenolic Curatives, Benzoquinone Derivatives, or Bismaleimides... 

VII. VULCANIZATION BY PHENOLIC CURATIVES, BENZOQUINONE DERIVATIVES, OR BISMALEIMIDES... 

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