What rubber is the basic raw material rubber industry, widely used in the manufacture of tires, hoses, plastic, cables and other various rubber products. Rubber Category:
1 raw materials into the natural rubber and synthetic rubber.
2 Press shape divided into blocks of raw rubber, latex, liquid rubber and powder rubber.
Latex rubber colloidal aqueous dispersion;
Liquid rubber rubber oligomers, before unvulcanized typically viscous liquid;
Powder latex rubber is processed into powder to facilitate formulation and manufacture.
3 is divided by the use of general-purpose and special type.
Better overall performance general-purpose rubber is widely used. The main are: ① natural rubber. ② isoprene rubber, known as synthetic natural rubber. ③ styrene-butadiene rubber, referred to as SBR. ④ butadiene rubber, referred to as BR.
Special type rubber that contains certain special properties of rubber. They are:
① silicone rubber, referred SILICONE
Main chain composed of alternating silicon-oxygen atoms with organic groups on the silicon atoms. High temperature resistance, ozone resistance, electrical insulation. Operating temperature -40 ℃ ﹋ + 220 ℃; oil is preferred, temperature, wear, oil! Especially suitable for the automobile engine crankshaft oil seal temperature is not volatile oils (diesel, gasoline) wear regard to oxygen, ozone and sunlight (UV) resistant.
② Viton. Viton
Sub-structure containing synthetic rubber fluorine atoms. Typically the number of fluorine atoms in the fluorine-containing copolymer units represented, such as fluorine rubber 23 is vinylidene fluoride with chlorotrifluoroethylene copolymer. Viton high temperature, oil, chemical resistant. Oil, high temperature resistance, chemical resistance, but also has the characteristics of acid. Operating temperature -30 ℃ + 280 ℃. Applicable in the jet engine crankshaft oil seal, Timing seal, also of agents for O-rings and seals

③ chloroprene rubber, referred to as CR.
Chloroprene polymerization. It has a good overall performance, oil, fire, resistance to oxidation and ozone. But its density, easy to crystallize at room temperature hardening, storage is bad, cold poor.
④ nitrile rubber, referred to as the NBR.
Butadiene and acrylonitrile copolymer obtained. Good oil resistance, heat resistance, cold resistance, pressure resistance and water resistance, air tightness and excellent bonding properties, and has a suitable wear resistance, the usual temperature of approximately -40 ℃ ~ + 120 ℃ may or long-term use in oil at 150 ℃ 120 ℃ in the air.
Ease of metal molded into an arbitrary shape hydraulic seal, therefore making best suited NBR operating pressure of not more than 32Mpa hydraulic cylinder seals. Specially designed recipes, easy to press the issue of resistance to oil: The wear can withstand the mechanical car axis speed 3000 rev / or less (in this case a rubber hardness of 70 °).
⑤ urethane rubber
The highest tensile strength of a synthetic rubber, it has excellent oil resistance, heat resistance, cold resistance, pressure resistance and abrasion resistance, the usual temperature is -40 ℃ ~ + 80 ℃, polyurethane rubber sealing properties at room temperature nitrile rubber is superior, it is particularly suitable for the production of medium, high and ultra-high pressure hydraulic cylinder seals.
⑥ Thiokol.
Polysulfides polycondensation dihaloalkane with an alkali metal or alkaline earth metal together. It has excellent oil and solvent resistance, but the intensity is not high, aging resistance, workability bad smell, and with more and nitrile rubber.
In addition, urethane rubber, epichlorohydrin rubber, acrylic rubber and the like.


Characteristics of silica gel
It is divided into coarse pore silica and silica pores

Silica gel can adsorb moisture, but also suck acetylene and carbon dioxide. As the temperature decreases, the first moisture adsorption (room temperature to about 25 ℃), followed by acetylene and carbon dioxide (the lower the temperature, the stronger the adsorption capacity).
Case size moisture adsorption / mm4 ~ 8 normal dynamic adsorption capacity /% 6-8 dry air moisture / g • m-3 0.03 dry air dew point / ℃ -52
Regeneration temperature / ℃ 140 ~ 160

Silica gel adsorption capacity for water is large, the regeneration temperature is low, the price is cheap, so ASU silicone is mainly used for adsorption of water, at a low temperature for adsorbing carbon dioxide and acetylene. The disadvantage is that the powder more.
Silicone has a rough two holes and pores, pore size difference between the two. Coarse pore silica pore size is 5 ~ 10nm (1nm = 10-9m, called nm) the specific surface area per gram of silica gel have 100 ~ 300m2 / g as much. Its absorption ability, and not broken after absorbing water, good mechanical strength, often adsorbs moisture in the dryer. Pore ​​silica gel pore size 2.5 ~ 4nm, a specific surface area of ​​400 ~ 600m2 / g. Used to absorb carbon dioxide and acetylene, adsorbs moisture easily broken. Carbon dioxide adsorption process adsorber is at -110 ~ -120 ℃ low temperature, the effect of better absorption of carbon dioxide, while also adsorption of acetylene. There will be less due to a temperature below -130 ℃ carbon dioxide solid precipitated solid carbon dioxide not only can not be adsorbed by silica gel and clog the adsorber. Adsorption of acetylene in the liquid air, liquid oxygen adsorption is carried out, the adsorption temperature of about -170 ~ -180 ℃.