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Discussion on the vulcanization of nitrile rubber

The molecular formula. General nitrile rubber vulcanizing agent sulfur, peroxide,resin curing!

Nitrile rubber used for sulfur vulcanizing agent, the NBR unsaturation was lower than that of natural rubber, the required amount of sulfur than natural rubber is a bit low, in order to speed up the curing speed, accelerator dosage may beslightly higher than that of natural rubber. When the content of acrylonitrilebutadiene rubber in high, relative content is low, the amount of sulfur can bereduced. Production of soft rubber, general sulphur content is 1.5~2, whencontent is more than 2.5, will make the vulcanizate hardness increase very quickly, the relative elongation decreased. Vulcanized with sulfur required to improve curing speed accelerator, commonly used in accelerator DM, CZ,TMTM, TMTD, and alkaline accelerator, such as aldehyde amine, Guanidines inwhen used alone, prone to scorch phenomenon and compression deformation increases, so does not apply. Sulfur with accelerator DM, CZ curing rate,properties of vulcanized rubber vulcanization system in common use is good. In the use of accelerator DM, the dosage is 1.5~2, sulfur 1.5 phr, the use of thispromoter, safe technology, scorch resistant performance after the rubber CZdelayed accelerant, vulcanized rubber tensile strength and tensile strength are high. Accelerator DM can also be used with other promoters to increase activity,and improve some properties of vulcanizates, such as can improve the tensile strength and lower compression deformation and TMTD bottle, but should pay attention to scorch, and dosage should be appropriate, when adding secondpromoter TMTD, was often is 1 DM and 0.15 a TMTD, TMTD 0.2~0.5, is easy toburn. When using CZ, the dosage is 0.5~1, sulfur 1.5 phr, glue the vulcanization system is not easy to burn, rubber aging resistance performance than DM,compression deformation is small. When using TMTM, was 0.6 phr, the sulfurcontent is 1 parts, vulcanized rubber tensile strength, elongation and high strength, small deformation, when the content of TMTM increased, the permanent deformation decreases. Zinc oxide, cadmium oxide, stearic acid as activator, zinc oxide were used in 5 copies, cadmium oxide content was 2~5,stearic acid is generally 1 copies. If no sulfur and non sulfur curing system, such as the use of TMTD curing about 3.5 copies, due to the structure of vulcanizatesto monosulfidic crosslinks advantage, and reduce the environmental pollution in the sulfur compounds, which obviously improve the vulcanizate heat aging resistance and tear resistance. When the content of TMTD is large, often spray frost phenomenon, mixed with part of accelerator CZ can eliminate this phenomenon. The sulfur system, such as the use of 2.5 TMTD and 0.2~0.3 ofsulfur vulcanized, vulcanized rubber has better heat aging properties and good mechanical properties. The CD mg curing system, the curing adhesive has excellent heat aging and heat aging properties and oil, small compression deformation. The main composition of nitrile rubber sulfur cadmium magnesiumsulfide system for cadmium oxide 2~5 parts, two ethyl two dithiocarbamate CD1.5~7 parts of magnesium oxide, 5 copies, 1 copies of the sulfur, acceleratorDM0.5~2.5. In the curing process, ultra accelerator two ethyl twodithiocarbamate CD can make vulcanized rubber mainly to generatemonosulfidic crosslinks, when the structure and cadmium oxide and can further improve the vulcanizate, improve the aging properties of vulcanized rubber heat.Two ethyl two dithiocarbamate CD was 2.5 phr can obtain performance the most suitable, cadmium oxide has the active agent role similar to the zinc oxide,reduce the dosage to reduce compression deformation, the dosage for long timecan improve the durability and thermal properties, use 5 can obtain good heat resistance and strength. As the second promoter of DM was 1 phr, can improve the heat resistance and reduced's scorching tendency. Magnesium oxide controlsizing pH value, dosage for optimum heat resistance and strength value of 5 phr.The disadvantage of cadmium sulfide system magnesium compound is easy toburn, such as in the system without sulfur and sulfur compounds such as thecarrier, by two vulcanization dual morpholine as curing agent, can make theimproved scorch tendency. The end of the molecule containing double bonds of unsaturated compounds, such as magnesium methacrylate, ethylene bis (methylacrylate), acrylamide in initiator (such as peroxide two Cumene) the presence ofvulcanized nitrile rubber effective crosslinks, and generate different types of.Performance and high temperature performance and vulcanized rubber has higher than low sulfur and sulfur system strong. Magnesium methacrylatevulcanizates with higher hardness, strength, tear than two cumene peroxidevulcanizates (especially the unfilled vulcanizates) and adhesive and metalstrength. Using magnesium methacrylate system is capable of producing highstrength of the unfilled filled rubber compound and high hardness. Silica gelcadmium magnesium vulcanization system material has excellent heat resistance, but the compression deformation, adding magnesium methacrylate,make it has excellent heat resistance, aging resistance and compressiondeformation reduced. General methacrylic acid magnesium content is 5 parts.Using the organic peroxide, such as peroxide cumene (two DCP), used in about 4 copies (concentration 40%) can make the rubber heat resistance, heat resistance and cold resistance of oil is improved, compression permanent deformation is also small and process safety. The drawback is poor tearresistance, elongation of short. In addition, the polyvalent metal oxides, such ascopper oxide, manganese dioxide, three two, five two antimony oxide oxidation ofvanadium can be used as the curing agent of acrylonitrile butadiene rubber,vulcanized rubber has good heat aging resistance and dynamic fatigueperformance, but these metal oxide vulcanization speed is slow, with a sort of vulcanizing accelerator has no effect, and with little DCP can accelerate thecuring speed.