1, nitrile rubber is mainly produced by low-temperature emulsion polymerization method, with excellent oil resistance, high abrasion resistance, good heat resistance and strong adhesive force. Its disadvantages are poor low-temperature resistance, poor ozone resistance, poor electrical properties, slightly lower elasticity.
Nitrile rubber is mainly used in the manufacture of oil-resistant rubber products. By butadiene and acrylonitrile **** polymerization and produced a synthetic rubber. It is a synthetic rubber with good oil resistance (especially alkane oil) and aging resistance. The acrylonitrile content (%) of NBR is 42-46, 36-41, 31-35, 25-30, 18-24 and so on. The more acrylonitrile content, the better the oil resistance, but the cold resistance decreases accordingly.
It can be used for a long time in air at 120℃ or in oil at 150℃. In addition, it also has good water resistance, air tightness and excellent bonding properties. It is widely used in making all kinds of oil-resistant rubber products, many kinds of oil-resistant gaskets, gaskets, casing, flexible packaging, flexible hose, printing and dyeing rubber rollers, cable rubber materials, etc. It has become an indispensable elasticity material in automobile, aviation, petroleum, photocopying, etc.?
Basic properties? NBR has excellent oil resistance, its oil resistance is second only to polysulfide rubber and fluorine rubber, and has the abrasion resistance and air tightness. The disadvantage of NBR is that it is not resistant to ozone and aromatic, halogenated hydrocarbons, ketone and ester solvents, so it is not suitable to be used as insulating material.
The main use of nitrile rubber is mainly used to make oil-resistant products, such as oil-resistant pipe, tape, rubber diaphragm and large oil bladder, etc. It is often used to make all kinds of oil-resistant molded products, such as O-ring, oil seal, leather bowl, diaphragm, flap, bellows and so on, and it is also used for the production of rubber plate and wear-resistant parts.?
The polarity of nitrile rubber is very strong, and the compatibility with other polymers is generally not very good, but with neoprene rubber, modified phenolic resin, PVC and other polar polymers, especially with chlorine-containing polymers with good compatibility, often used in parallel. In addition, in order to improve the processability and performance, NBR is also often used with natural rubber, styrene butadiene rubber, butadiene rubber and other non-polar rubber. It should be noted that: NBR is characterized by good oil resistance, and other polymers (except PVC) are used in conjunction with a tendency to reduce oil resistance.
2, fluorine rubber molecular structure contains fluorine atoms in the synthetic rubber, is a high temperature, oil, chemical corrosion-resistant special rubber. There are many varieties, usually to *** polymer containing fluorine units of the number of fluorine atoms to indicate, for example: fluoroelastomer 23 is vinylidene fluoride with chlorotrifluoroethylene *** polymer, fluoroelastomer 246 is vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene *** polymer, fluoroelastomer 26 is vinylidene fluoride and hexafluoropropylene *** polymer and so on.
Fluoroelastomer 26 is white, odorless, non-toxic, non-flammable solid, its outstanding characteristics are high temperature resistance, chemical resistance, oil resistance and oxidation resistance, can be used at 250 ℃ for a long time, 300 ℃ short-term use. Its vulcanized rubber tensile strength of 7.0 ~ 17.5MPa, elongation of 150% ~ 300%, weather resistance, ozone resistance, excellent electrical insulation properties, permeability lower than other rubbers. Fluoroelastomer 23 resistance to strong oxidation is outstanding. The main disadvantage of fluoroelastomer is poor low-temperature resistance, higher density, higher prices.
Use of fluoroelastomer in aviation, aerospace, automotive, oil, petrochemical, industrial pollution control is essential? s special synthetic rubber, mainly used in the manufacture of high-temperature, oil, chemical corrosion-resistant gaskets, seals and other seals; secondly, used in the manufacture of hoses, impregnated products and protective gear, etc..
3, the molecular main chain of silicone by silicon atoms and oxygen atoms alternately composed of a molecular chain both inorganic and organic properties of polymer elastic materials. Now the most widely used, the most is methyl vinyl silicone rubber, which is made of dimethyl silicone and a small amount of vinyl silicone **** polymerization.
Silicone is a colloidal substance with solid properties, and its basic component is silicon dioxide (SiO2). The physical structure of silica gel is rich in micropores and high specific surface area, its surface for the silica hydroxyl structure, so it has a strong adsorption of water vapor or other polar substances as well as selective adsorption and separation ability, in the adsorption, drying, separation of substances, purification, high purity preparation and other fields have a wide range of applications. In the field of chemical engineering, silica gel can be used as a catalyst or catalyst carrier.
Silica gel has the following advantages in application due to its chemical composition and physical structure:
(1) chemically stable, insoluble in any other solvents and solutions except for hydrofluoric acid (HF) and strong bases;
(2) thermally stable, A-type fine-pore silica gel can be used at temperatures of up to 300°C, while other types of silica gel are Can be used for a long time under the high temperature of 500-600 ℃;
(3) Silica gel has a rigid skeleton structure, good wear resistance and compressive strength.
Silicone series of products of each species has its own characteristics, this is because the silicone in the manufacturing process can be controlled by the corresponding process conditions to get different types of pore structure and adapt to different applications.
Expanded Information:
Fluoroelastomer Key Applications: Because of the Fluoroelastomer's resistance to high temperatures, oil, High vacuum and acid and alkali resistance, resistance to a variety of chemicals, has been applied to modern aviation, missiles, rockets, cosmic navigation, ships, atomic energy and other cutting-edge technology and automobiles, shipbuilding, chemical, petroleum, telecommunications, instruments, machinery and other industrial fields.
Fluoroelastomer typical applications:
Fluoroelastomer seals, used for engine sealing, can be used in 200 ℃ ~ 250 ℃ for long-term work, short-term work at 300 ℃, and its working life can be the same as the engine rebuild life of 1,000 ~ 5,000 flight hours (time of 5 ~ 10 years).
Used in the chemical industry, it can seal inorganic acids (such as 67% sulfuric acid at 140 ℃, 70 ℃ concentrated hydrochloric acid, 30% nitric acid), organic solvents (such as chlorinated hydrocarbons, benzene, highly aromatic gasoline) and other organic substances (such as butadiene, styrene, propylene, phenol, 275 ℃ fatty acids, etc.).
When used in deep well oil recovery, it can withstand the harsh working conditions of 149℃ and 420 atmospheres; when used in superheated steam seals, it can be used for long term work in steam media at 160~170℃. In the production of monocrystalline silicon, commonly used fluoroelastomer seals to seal the high temperature (300 ℃) under the special media - trichlorohydrosilicon, silicon tetrachloride, gallium arsenide, phosphorus trichloride, trichloroethylene, and hydrochloric acid 120 ℃, etc..
In high vacuum applications, when the flight altitude of 200~300Km, the air pressure is 133×10-6 Pa (10-6mmHg), neoprene rubber, butyl rubber, butyl rubber can be applied.
When the flight altitude exceeds 643Km, the air pressure will drop to 133×10-7 Pa (10-7mmHg) below, in this high vacuum only fluorine rubber can be applied. Generally in the high vacuum or ultra-high vacuum device system before use, need to go through a high-temperature baking treatment, 26-type, 246-type fluoroelastomer can withstand high-temperature aging of 200 ℃ ~ 250 ℃, and therefore become a high-vacuum equipment and cosmic vehicles in the most important rubber materials.
Fluoroelastomer hose is suitable for high temperature, oil and special media resistant occasions, such as aircraft fuel oil, hydraulic oil, synthetic bi-ester oil, high temperature hot air, hot inorganic and other special media (such as chlorinated hydrocarbons and other chlorinated compounds) of the transport, guidance and so on. Made of fluoroelastomer wire and cable flexing good, and good insulation. Fluorine rubber made of fiberglass tape, can withstand high temperatures of 300 ℃ and chemical corrosion resistance.
Aramid cloth coated with fluoroelastomer can be made of petrochemical plants, high-temperature, acid and alkali class tanks between the connecting telescopic tube (both ends can be connected with metal flanges), which can withstand high pressure, high temperature and corrosion of the medium and the deformation of the two tanks expansion and contraction of the cushion shock-absorbing connecting role. Nylon cloth coated with fluorine adhesive made of adhesive tape sealing bag, as a refinery within the floating roof storage tanks with soft seals, play a role in sealing, reduce the volatility of the oil level loss.
Type 23, tetrapropyl fluorine rubber is mainly used as acid-resistant, corrosive sealing occasions resistant to special chemicals. Hydroxy nitrosofluoroelastomer is mainly used as protective products and sealing products, in the form of solution as a non-combustible coating, applied to fire-resistant electronic components and parts working in pure oxygen.
The solution and liquid rubber can be sprayed, casting and other methods to manufacture many products, such as cosmic clothing, gloves, pipe bands, balls and so on. Can also be used as a glass, metal "se sex body, fabric adhesive, the manufacture of sponges and contact with rocket propellant (N2O4) gaskets, "O" rings, capsules, valves Yin category of various types of seals, etc..
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