Elastomers vulcanization agents

Sulfur is the almost universal, primary vulcanizing agent for all elastomers, whether in latex or dry form. Less sulfur is normally required for latex than for dry mbber compounds. By increasing sulfur concentration to 30—50 parts by weight (30—50 parts/100 parts dry mbber content (DRC)) in latex compound, satisfactory hard mbber articles, particularly mbber—metal coatings, are obtained. 

AH of the polyether elastomers, like other vulcanizable elastomers, can be compounded with processing aids, fillers, plasticizers, stabilizers, and vulcanizing agents to make useful mbber products. A typical compounding recipe for epichlorohydrin elastomer is as follows ... 

Compatibilization along with dynamic vulcanization techniques have been used in thermoplastic elastomer blends of poly(butylene terephthalate) and ethylene propylene diene rubber by Moffett and Dekkers [28]. In situ formation of graft copolymer can be obtained by the use of suitably functionalized rubbers. By the usage of conventional vulcanizing agents for EPDM, the dynamic vulcanization of the blend can be achieved. The optimum effect of compatibilization along with dynamic vulcanization can be obtained only when the compatibilization is done before the rubber phase is dispersed. 

In order to support and meet this demand, an all-around development has taken place on the material front too, be it an elastomer new-generation nanofiller, surface-modified or plasma-treated filler reinforcing materials like aramid, polyethylene naphthenate (PEN), and carbonfiber nitrosoamine-free vulcanization and vulcanizing agents antioxidants and antiozonents series of post-vulcanization stabUizers environment-friendly process oil, etc. 

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. 

Sulfur Chief vulcanizing agent for many elastomers, particularly those based entirely or part on butadiene or isoprene. 

Sulfur-vulcanizable elastomers have been prepared that are designed to reduce hysteresis in tires by reducing the number of polymer free ends. The method for this preparation entails anionically preparing poly(styrene-co-butadiene) using a lithium thioacetal initiator followed by incorporation of a vulcanization agent into the elastomer terminus. 

TABLE 2. Physical properties of styrene-butadiene elastomers initiated with selected thioacetals and terminated with vulcanization agents. 

Elastomers are prepared by chain extension of hydroxyl-terminated low-molecular-weight polymers followed by vulcanization 180). The most important work concerns the use of hydroxy telechelic polybutadienes and polyisoprenes in the tire industry 249 252>. The hydroxylated polydienes of molecular weight 1000-20000 are mixed with a diisocyanate, a catalyst, vulcanization agent (sulfur), and accelerator, reinforcing additives (carbon black), and surface-active agents. The reaction takes place in two steps simultaneously or consecutively ... 

DBQDO . [Lord] Dibenzoyl-p-quinone dioxime vulcanizing agent for natural and synthetic elastomers. 

Vul-Cup. [Hercules] Bisperoxide vulcanizing agent and polymerization catalyst fcx elastomers and plastics. 

DBQDOtSi . [LorQ Dibenzo -p-quinone dioxime vulcanizing agent to natural and syndietic elastomers. 

Varox . [R.T. Vanderbilt] Pooxide derivs. crosslinking and vulcanizing agent for elastomers, plastics. 

A typical rubber formulation, for example, that demonstrates the surface area properties of silica sol can be seen in the Talalay process for making foam rubber [24] the elastomer foam is in a latex form, to which is added an accelerator, an antioxidant, a vulcanizing agent, and carbon black. The mixture is then foamed, either mechanically or chemically, gelled, vulcanized to... 

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