Coagents triallyl cyanurate

Coagents are often used with peroxides to increase the state of cure. Some coagents, such as polybutadiene or multifunctional methacrylates, are used at high levels to form polymer grafts or interpenetrating networks. Other coagents such as triallyl cyanurate, triallyl trimellitate, and meta-phenylene bismaleimide are used at low levels to reduce the tendency of the polymer to degrade by chain scission. 

EPDM ethylene propylene diene rubber with 50 wt% paraffinic oil extended, PP polypropylene, DTBT 2,4-diallyloxy-6-fer/-butylpcroxy-1,3,5-triazinc (95% pure), DCP dicumyl peroxide (40% pure), TAC triallyl cyanurate (50% pure), 1076-Irganox 1076, 168-Irgafos 168 Values in the parentheses correspond to the milliequivalent concentration of corresponding peroxide and coagent per 100 parts of pure EPDM rubber... 

Sulfur, or the so-called coagents (Loan, 1963 Lenas, 1964), can be used to suppress scission. Examples of coagents are m-phenylenebismaleimide, high-1,2 (high-vinyl)polybutadiene, triallyl cyanurate, diallyl phthalate, and ethylene diacrylate. Their mechanism of action may be as follows ... 

Several papers have been published that describe the use of zinc diacrylate (ZDA) and ZDMA as coagents to improve the physical properties of rubbers [10, 11, 12, 13 and 14]. In this context, they are referred to as metallic coagents. They differ from conventional rubber coagents, like triallyl cyanurate (TAC) and TRIM, in that they have ionic bonds that become part of the crosslink network. The ionic bonds allow for a flexible and more forgiving network, particularly at high crosslink levels. This can lead to rubber products with good dynamic properties and a good combination of physical properties. 

Representative coagents of this type include triallyl cyanurate and polyallyl ethers and esters. 

Regular butyl rubbers undergo molecular mass reduction under the aetion of peroxides, but halobutyl rubbers (partieularly BIIR) are capable of being cross-linked with peroxides (12 phr). In order to attempt an optimum eure and optimum properties, a suitable coagent is required (metaphenylene bismaleimide, triallyl cyanurate, polyfunetional methacrylates). 

MBM), triallyl isocyanurate (TAIC), and triallyl cyanurate (TAC). These coagents provide a more stable free radical source by reacting with the free radicals formed from peroxide decomposition. These more stable free radicals formed by the combination of the decomposed organic peroxide and the coagent are then more likely to react with the HNBR polymer to form effective cross-links. An excellent study of the interaction of peroxides and coagents was conducted by Zeon Chemicals and shows the utility of statistical experimental design and response surface methods to provide a comprehensive picture of this interaction [8]. The compounds used in this... 

Coagents should be used with the peroxide to obtain a satisfactory rate and state of cure. Commonly used coagents are TAC (triallyl cyanurate), TATM (triallyl trimelli-tate), HVA-2 (iV.M-m-phenylene-dimaleimide), di- or tri-methylacrylates, liquid high 1,2 polybutadiene, diaUyl phthalates, and others. The allylic types provide better process safety and are more effective in CSM. 

As the amount of either the peroxide or coagent, such as Triallyl Cyanurate, is increased, the modulus, or state of cure, increases, and the elongation, tensile strength, tear strength, and compression set decreases. Figure 9.8 illustrates this effect on the physical properties of a peroxide/coagent cured CSM. 

Polymer B is that prepared with perfluoroisopropyl iodide it can be considered to have terminal iodine on one side (mono-iodide-copolymer). Polymer C is that prepared with 1,4-di-iodo-perfluorobutane it can be considered to have terminal iodines on both sides (di-iodide-copolymer). In the cases of polymer B and C, it is found that the gel fractions of thier vulcanizates are increased using various kinds of multifunctional vinyl compounds, and that triallyl iso-cyanurate(TAIC) is the most effective coagent. On the other hand, no gel is found in the case of vulcanizates prepared from polymer A even it was cured using TAIC. These experimental results suggest the terminal iodines react with TAIC and form gel. 

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