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To some extent zinc stearate can partially replace stearic acid and zinc oxide, but stearic acid and zinc oxide in rubber can not be fully reactive and have their own role.
Zinc oxide and stearic acid in the sulfur vulcanisation system constitute the activation system, its main functions are as follows.
1, activate the vulcanisation system: ZnO and SA generate zinc soap, which improves the solubility of ZnO in rubber, and with the accelerator to form a good solubility complex in rubber, activate the accelerator and sulphur, improve the vulcanisation efficiency.
1, activate the vulcanisation system: ZnO and SA generate zinc soap, which improves the solubility of ZnO in rubber, and with the accelerator to form a good solubility complex in rubber, activate the accelerator and sulphur, improve the vulcanisation efficiency.
2、Improve the cross-linking density of vulcanised rubber:ZnO and SA generate soluble zinc salts, zinc salts chelate with cross-linking bonds, protect the weak bonds, make the vulcanisation to generate short cross-linking bonds, and increase new cross-linking bonds, improve the cross-linking density.
3, improve the aging resistance of vulcanized rubber: vulcanized rubber in the process of use, polysulfide bond breakage, the generation of hydrogen sulfide will accelerate the aging of rubber, but ZnO and hydrogen sulfide to generate zinc sulfide, consumption of hydrogen sulfide, reducing the hydrogen sulfide on the catalytic decomposition of the crosslinked network; in addition, ZnO can sew broken sulfur bond, the cross-linking bonds play a stabilizing role.
4, reflecting different mechanisms: in different vulcanisation with the system, different vulcanisation accelerator mechanism is very different, ZnO and SA reaction to form zinc stearate intermediates and the role of separate use of zinc stearate mechanism is not the same.
Therefore, it is necessary to choose the appropriate combination according to different design ideas in the formulation design.
