What is EPDM rubber?
EPDM rubber is a copolymer of ethylene, propylene and a small amount of non-conjugated diene. It is a kind of ethylene-propylene rubber, represented by EPDM, because its main chain is composed of chemically stable saturated hydrocarbons, only in the side chain. It contains unsaturated double bonds, so it has excellent aging resistance such as ozone resistance, heat resistance, weather resistance, etc. It can be widely used in automotive parts, waterproof materials for construction, wire and cable jackets, heat-resistant hoses, tapes, automotive seals and other fields.
The main chain of its molecular structure does not contain double bonds, and has high chemical stability, excellent electrical insulation properties and water resistance. In addition, because of its own chemical structure, EPDM rubber belongs to the isoprene rubber family, which has very good mixing properties. Among all plastics, EPDM has a low proportion. It absorbs a lot of fillers and oils without damaging properties too much.
Technical parameters of EPDM rubber
1. According to the voltage level, it can be divided into:
(1) 5KV high voltage insulating rubber sheet Technical parameters: thickness 3mm; color red, black, green; specific gravity: 5.5KG/m2
(2) 10KV high voltage insulating rubber sheet Technical parameters: thickness 5mm; color red, black, green; specific gravity: 9KG/m2
(3) 15KV high voltage insulating rubber sheet Technical parameters: thickness 6mm; color red, black, green; specific gravity: 9KG/m2
(4) 25KV high voltage insulating rubber sheet Technical parameters: thickness 8mm; color red, black, green; specific gravity: 14.5KG/m2
(5) 35KV high voltage insulating rubber sheet Technical parameters: thickness 10mm-12mm; color red, black, green; specific gravity: 21.6KG/m2
The main characteristics of EPDM rubber
(1) Low density and high filling
EPDM rubber is a low density rubber with a density of 0.87. In addition, it can fill a large amount of oil, add fillers, reduce the cost of rubber products, and make up for the high price of EPDM raw rubber. And for ethylene-propylene rubber with high Mooney value, the physical and mechanical energy drop is very small after high filling.
The density of EPDM rubber sheet is a lower rubber, and its density is 0.87. In addition, a large amount of oil can be added and fillers can be added, so the cost of rubber products can be reduced, making up for the disadvantage of high price of ethylene-propylene rubber raw rubber, and for ethylene-propylene rubber with high Mooney value, the physical and mechanical energy after high filling is reduced.
(2) Weather resistance
EPDM rubber has excellent weather resistance, weather resistance means that it has the ability to resist extreme cold, extreme heat, dryness and humidity for a long time, and has excellent corrosion resistance to the corrosion of rain and snow water, which can completely extend the application of the rubber strip. life;
(3) Heat aging resistance
Heat aging resistance refers to strong heat aging resistance. It can be used at 100-120 ℃ for a long time, and it can also maintain effective physical properties for a moderately long period of time at 140-150 ℃. It can withstand high temperature of 230-260 ℃ in a short time. It has a time-delay effect; coupled with the use of a special formula, the EPDM rubber feels around -50 ℃ to 150 ℃, which creates a high-efficiency operation performance for the production site device.
(4) Ozone resistance
Because EPDM has excellent ozone resistance, it is also known as "crack-free rubber". It is especially used in various urban buildings with different atmospheric indices and completely exposed to the air, and it will show the product's quality.
(5) Acid and alkali resistance
Due to its non-polarity and low unsaturation, EPDM has good resistance to various polar chemicals, such as acids, alkalis, oxidants, detergents, animal and vegetable oils, etc. But it has poor stability in aliphatic, aromatic and mineral oils. Under the long-term action of concentrated acid, the performance will also decrease.
Due to the non-polar substituents in the molecular structure of EPDM, the molecular cohesion energy is low, and the molecular chain can remain flexible in a wide range, second only to natural rubber and cis-butadiene rubber, and can still be maintained at low temperatures. Low temperature elasticity is good, and the temperature when stretching can reach 100MPa is -58.8℃.
(7) Corrosion resistance
Due to the lack of polarity and low degree of unsaturation, the EPDM rubber sheet is good for a variety of polar chemicals such as alcohols, acids, alkalis, oxidants, refrigerants, detergents, animal and vegetable oils, ketones and greases. Good resistance; but poor stability in aliphatic and aromatic solvents (such as gasoline, benzene, etc.). The performance will also decrease under the action of concentrated acid.
(8) Water vapor resistance
EPDM sheet has good water vapor resistance and is estimated to be better than its heat resistance. In the superheated steam at 230°C, there is no change in appearance after nearly 100h. However, under the same conditions, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, and natural rubber experience obvious deterioration in appearance after a short period of time.
(9) Resistance to superheated water
The performance of EPDM rubber sheet is also good in resistance to superheated water, but it is closely related to combing.
(10) Electrical properties
The EPDM rubber sheet has good electrical insulation properties and corona resistance, and the EPDM rubber sheet can withstand voltages of 60-150KV. The electrical properties are better than or close to styrene-butadiene rubber, chlorosulfonated polyethylene, polyethylene and cross-linked polyethylene.
(11) Anti-ultraviolet radiation
The EPDM rubber sheet is resistant to ultraviolet radiation and provides environmental protection for the residents of high-rise buildings.
The use of EPDM rubber
Ethylene-propylene rubber is synthesized with ethylene and propylene as the main raw materials, and has outstanding aging resistance, electrical insulation properties and ozone resistance. Ethylene-propylene rubber can be filled with a large amount of oil and carbon black, and the product price is low. The chemical stability of ethylene-propylene rubber is good, and its wear resistance, elasticity, and oil resistance are similar to those of styrene-butadiene rubber. Ethylene-propylene rubber has a wide range of uses. It can be used as tire side, rubber strip and inner tube, as well as parts of automobiles, as well as wire and cable sheathing and high-voltage and ultra-high-voltage insulating materials. It can also manufacture light-colored products such as shoes and sanitary products.
Because of its excellent physical and mechanical functions, EPDM rubber is often used to make sealing parts of aircraft, automobiles, trains, passenger cars, ships, high and low voltage switch cabinets, glass curtain walls, aluminum alloy thermal insulation windows and diving products, high-voltage Steam hoses, tunnels, viaducts, waterproof parts and other industrial and agricultural sealing parts.
EPDM rubber sheets are mainly used in power distribution rooms and power distribution stations. They are used for laying the ground of power distribution equipment and play an insulating role. In the dry season, the humidity is high, and the insulation protection operation is more important. For the sake of safety, many power distribution rooms and power distribution rooms have begun to use high-level insulating rubber pads, so the demand for products has increased a lot.
Application and performance of EPDM rubber sheet for railway
Rubber is not only used in the power industry, but also in a wide range of other industrial fields. The color of insulating rubber is also very diverse, mainly black, red, green and so on. Thickness can be customized according to customer needs. A good insulating rubber has good insulating properties, does not contain non-insulating substances in the material, and has excellent mechanical properties.
EPDM rubber sheet for railway is a copolymer of ethylene, propylene and a small amount of non-conjugated diene. It is a kind of ethylene-propylene rubber. It is represented by EPDM. The side chain contains unsaturated double bonds, so it has excellent aging resistance such as ozone resistance, heat resistance, weather resistance, etc. It can be widely used in car parts, waterproof materials for construction, wire and cable sheaths, heat-resistant hoses, tapes, and car seals items, etc.
EPDM rubber sheets for railways choose different rubber sheets according to their different operating conditions, and different environments and actual application requirements have different optional processes. For example, the rubber sheets selected for the on-site construction process are cooked rubber. Plate or self-vulcanized rubber plate, when the ambient temperature is too high, generally use the vulcanization tank hot vulcanization method to vulcanize the rubber plate to improve the temperature resistance of the rubber plate, especially for mining and thermal power plants with short maintenance time, wear-resistant rubber plate. Under the conditions of higher requirements, the selected on-site cold-bonding technology research has greatly reduced the cost of its enterprise and improved the service life.