The rubber seals produced by EPDM rubber are excellent in high and low temperature resistance and anti-aging properties, and can maintain good sealing effect in a variety of extreme environments for a long time; EPDM rubber and EPDM reclaimed rubber are used together. The main way of EPDM seals at present; when using EPDM rubber/recycled rubber to produce rubber seals, the vulcanization system directly affects the mechanical properties and compression set resistance of the seals; then the vulcanization commonly used in EPDM seals in actual production What are the systems? How to choose?
Under normal circumstances, EPDM/recycled rubber is used in the production of rubber seals. Sulfur vulcanization system and peroxide vulcanization system are often used. The characteristics of vulcanization process of two different vulcanization systems and the impact on EPDM seals are as follows: .
1. Vulcanization characteristics of two curing systems
Sulfur vulcanization system uses sulfur as vulcanizing agent, and the vulcanizing agent commonly used in peroxide vulcanization system is DCP, which is vulcanized under the combination of vulcanization accelerator and active agent; when ethylene propylene diene monomer/recycled rubber is vulcanized, sulfur The vulcanization time of the vulcanization system and the peroxide vulcanization system are basically the same, but the scorch time is prolonged when sulfur vulcanization is used.
2. Effect of two vulcanization systems on mechanical strength of EPDM vulcanizates
The research shows that the tensile strength and elongation at break of the EPDM/recycled rubber after sulfur vulcanization are similar to those of peroxide vulcanizate, but the hardness of EPDM vulcanizate with sulfur vulcanization system is greater. When rubber seals are produced using EPDM rubber and EPDM reclaimed rubber, the higher the hardness and the greater the inter-molecular stress, the better the seal sealing effect.
3. Effect of vulcanization system on compression set of EPDM seals
Sulfur vulcanization and peroxide vulcanization have different types of crosslink bonds, in which the sulfur vulcanized EPDM vulcanizate network is mainly composed of polysulfide crosslinks, and peroxide vulcanization forms carbon-carbon crosslinks. Key, wherein the bond energy of the carbon-carbon crosslink bond is higher than that of the polysulfide bond and the monosulfide bond bond, and the peroxide-cured EPDM vulcanizate has a lower compression set than the sulfur vulcanizate at a higher temperature. a lot of.
When using EPDM rubber and EPDM reclaimed rubber to produce rubber seals, the hardness and compression set of vulcanizate are the main factors affecting the seal sealing effect and service life, generally used at higher temperatures. EPDM seals are mostly selected for peroxide vulcanization, while seals with higher hardness in mechanical strength are sulfur vulcanized, or sulfur and peroxide can be used together with a suitable variety of accelerators to produce ternary The overall performance of ethylene-propylene rubber seals is better.