Elastomers vulcanization agents peroxide cross-linking

Dicumyl peroxide n. [C6H5C(CH3)20]2. A vulcanizing agent for elastomers, also used to cross-link polyethylene. 

Peroxides are probably the most common materials used instead of sulfur for rubber vulcanization, because of their ability to cross-link a variety of unsaturated and saturated elastomers and also their ability to produce thermally stable carbon-carbon cross-links. There are also some disadvantages of peroxide cross-linking. The most important are the poor mechanical properties of vulcanizates and low crosslink efficiency [1,2]. The use of co-agents coupled with peroxides to cure elastomers has been a common practice... 

A wide variety of vulcanization agents are used in the rubber industry. For specialty elastomers, peroxide cross-linking is probably the most widely used and fastest growing system. The various peroxides available for cross-linking and newer developments in this area will be reviewed. Other vulcanization agents for specialty elastomers will also be presented. 

These steps are typical for most of the synthetic elastomers. The use of sulfur for vulcanization is common for the production of most elastomers. Magnesium and zinc oxides are often used for the cross-linking of polychloroprene (CR). Saturated materials such as EPM and fluoroelastomers are cross-linked using typical organic cross-linking agents such as peroxides. 

Nonsulfur Vulcanizing Agents. Many high performance specialty elastomers do not contain diene moieties in their molecular structure and therefore cannot be sulfur-cured. These elastomers require cross-linking agents capable of reacting with the specific functional group(s) contained by the specific elastomer. Some common nonsulfur curatives include peroxides, difunctional resins, and metal oxides. 

Peroxides are highly efficient vulcanizing agents for elastomers and plastics. In addition they are used as polymerization catalysts in the coatings industry. Tliese materials are commercially available in several physical forms and container types to suit the needs of users. Sulfur vulcanization of rubber was discovered in the early 1800s. The cross-linking of natural rubber with a peroxide was discovered in 1914 by a Russian, who used benzoyl peroxide. However, benzoyl peroxide vulcanizates have lower strength and poorer heat resistance than do sulfur vulcanizates. In 1950... 

The new co-agents revealed high tendency to agglomeration in elastomer matrix what had a beneficial effect on vulcanizates mechanical properties. ApplicatitMi of unsaturated acids and metal oxides as the new co-agents in peroxide vulcanization of HNBR caused mostly a decrease of vulcanization time, considerable improvement of vulcanizates mechanical properties, as well as the increase of cross-link efficiency. Thus, they may be used successfully in rubber technology. 

The elastomers based on vinylidene fluoride are saturated and cannot be vulcanized with sulphur. As with other saturated rubbers cross-linking can be brought about by irradiation and by the use of peroxides but the only agents of commercial importance until the 1970s were diamines and certain of their derivatives. Of particular importance have been the amine carbamates which are somewhat less reactive and less likely to scorch (premature vulcanization) during processing. Typical materials of this class are ethylene diamine carbamate (IX), hexamethylene diamine carbamate (X) and N,N -dicinnamylidene-1,6-hexane diamine (XI) ... 

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