Description of the characteristics of different materials of the seal

Fluororubber has a high degree of chemical stability and is currently the best medium for all media. Sealing type 26 fluororubber resistant to petroleum-based oils, diester oils, silicone ether oils, silicic oils, resistant to inorganic acids, resistant to most organic, inorganic solvents, pharmaceuticals, etc., only resistant to low molecular weight ketones, Ether, ester, not resistant to amine, ammonia, hydrofluoric acid, chlorosulfonic acid, phosphoric acid hydraulic oil. The properties of the 23 type fluorine rubber are similar to those of the type 26, and it is more unique. Its inorganic acid with strong oxidizing properties such as fuming nitric acid and concentrated sulfuric acid is better than the type 26, and is impregnated with 98% HNO3 at room temperature. Its volume expansion is only 13% to 15%. Fluororubber has excellent physical and mechanical properties. The type 26 fluororubber generally has a strength of between 10 and 20 MPa, an elongation at break of between 150 and 350%, and a tear strength of between 3 and 4 KN/m. The type 23 fluororubber has a strength between 15.0 and 25 MPa, an elongation of 200% to 600%, and a tear strength of 2 to 7 MPa.

    Generally, the fluororubber has a large compression set at high temperature, but if compared with the same conditions, such as the compression set at 150 ° C for the same time, the seal butyl and neoprene are larger than the 26 fluoro rubber. The compression deformation of the type 26 fluororubber at 200 ° C for 24 hours corresponds to the compression deformation of the butadiene rubber at 150 ° C for 24 hours. The low temperature performance of fluororubber is not good due to its own chemical structure, such as Tg > 0 ° C of type 23-11. The low temperature properties of the actually used fluororubber are usually expressed by the brittle temperature and the compression cold resistance coefficient. The formulation of the compound and the shape (such as thickness) of the product have a relatively large influence on the brittleness temperature. If the amount of the filler in the formulation is increased, the brittle temperature is sensitively deteriorated, the thickness of the product is increased, and the brittleness is also sensitively deteriorated.