The accelerators used in nitrile butadiene rubber are mainly autumn Lamb and thiazole, in which the vulcanizate properties of autumn Lamb accelerators are better, especially the compression permanent deformation is good, and the processing is safe, so the application is more common. In addition, sulfonamide accelerators are also used. Amines and guanidine promoters are often used as co-promoters. Sulfur has different properties when used with different accelerators, for example, using thiuram disulfide (such as accelerator TMTD, TRA, TRT 0.25 phr, 0.5 phr) with sulfur, low sulfur or no sulfur, excellent heat resistance. When sulfur is blended with accelerator MD or CZ, the compound has good strength and elongation properties, so it is a commonly used curing system, such as S/DM (1.5 × 1.5), and when sulfur is blended with tetramethylthiuram, such as TS, the compound has lower compression permanent deformation and minimum scorch tendency. The low sulfur formula with high amount of thiosulfonamides and sulfonamides or thiazoles and thiazoles has excellent physical and mechanical properties, good heat resistance, small compression permanent deformation, and not easy to scorch and frost spraying.
In order to reduce the permanent deformation, the combination of a small amount of sulfur and autumn Lamb is extremely effective. the formula is characterized by small permanent deformation but shorter scorch time. Zinc oxide and stearic acid are often used as vulcanizing agents. The dosage of zinc oxide in sulfur vulcanization and sulfur-free vulcanization system is usually 1.0-5.0 phr, the customary dosage of zinc oxide is 5 phr, and the amount of stearic acid is generally 1.0 phr. The vulcanization system of sulfur-containing compounds is a vulcanization system in which sulfur-containing compounds (sulfur carriers), such as thiuram and morpholine disulfide, are used as curing agents. This vulcanization system does not use sulfur and is conventionally called sulfur-free vulcanization system. The commonly used vulcanizing agents of nitrile butadiene rubber are tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide (TET), tetrapentamethylthiuram tetrasulfide (TRA), dosage 1 phr and so on. Qiuram curing agents are easy to spray frost, so products with strict appearance requirements should be used carefully. In order to avoid damage and spray cream, morphine disulfide can be used at a dosage of 2-4 phr, or it can be used in combination with morpholine disulfide or with accelerator CA as vulcanizing agent.
The useful and effective curing system of nitrile butadiene rubber can improve the thermal aging resistance of vulcanizate and reduce the compression deformability. For example, 0.5 phr of sulfur, TMTD1.0 phr, CZ1.0 phr, has good heat aging resistance. Accelerators that can be used in natural rubber can be used in nitrile butadiene rubber.
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