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Characteristic Analysis of EPDM Sealing Material of Two-way Two-position Electromagnetic Valve
Two-way two-position solenoid valve sealing material EPDM rubber is a terpolymer of ethylene, propylene and non-conjugated diene. The most important feature of EPDM is its superior resistance to oxidation, ozone and corrosion. Since EPDM rubber belongs to the polyolefin family, it has excellent vulcanization properties. Among all rubbers, EPDM has the lowest specific gravity. It can absorb large amounts of fillers and oils without affecting the characteristics. Therefore, a low-cost rubber compound can be produced.
Two-way two-position electromagnetic valve sealing material EPDM molecular structure and characteristics:
Ethylene propylene glycol is a terpolymer of ethylene, propylene, and a non-conjugated diene. Diolefins have a special structure, only one of the two bonds can be copolymerized, unsaturated double bonds are mainly used as the link. The other unsaturation does not become the polymer backbone and only becomes a side chain. The main polymer chain of ethylene propylene diene is completely saturated. This feature makes EPDM resistant to heat, light, oxygen, and especially ozone. EPDM is essentially non-polar, resistant to polar solutions and chemicals, has low water absorption, and has good insulating properties.
Two-way two-position solenoid valve sealing material EPDM rubber features:
1. Low density and high filling
The density of ethylene propylene rubber is a lower rubber with a density of 0.87. In addition, a large amount of oil can be filled and fillers can be added, which can reduce the cost of rubber products, make up for the disadvantages of the high price of ethylene-propylene rubber raw rubber, and reduce the physical and mechanical properties of high-impregnated ethylene-propylene rubber. Not much.
2. Aging resistance
Ethylene propylene rubber has excellent weather resistance, ozone resistance, heat resistance, acid and alkali resistance, water vapor resistance, color stability, electrical properties, oil-filling properties, and normal temperature fluidity. Ethylene propylene rubber products can be used at 120°C for a long period of time, and can be used short or intermittently at 150-200°C. Adding a suitable antioxidant can increase its use temperature. Peroxide-crosslinked EPDM rubber can be used under more severe conditions. EPDM rubber can crack for more than 150h under the conditions of ozone concentration 50pphm and 30% stretch.
3. Corrosion resistance
Because ethylene propylene rubber lacks polarity and low degree of unsaturation, it has good resistance to various polar chemicals such as alcohols, acids, alkalis, oxidants, refrigerants, detergents, animal and vegetable oils, ketones and fats. However, stability is poor in aliphatic and aromatic solvents (such as gasoline, benzene, etc.) and mineral oils. In the long-term effect of concentrated acid performance also decline.
4. Water vapor resistance
Ethylene propylene rubber has excellent water vapor resistance and is superior to its heat resistance. In the 230~C superheated steam, the appearance did not change after nearly 100 hours. Fluoroelastomer, silicone rubber, fluorosilicone rubber, butyl rubber, nitrile rubber, and natural rubber underwent obvious deterioration of the appearance in a relatively short time under the same conditions.
5 resistance to hot water performance
Ethylene-propylene rubber is also resistant to overheating, but it is closely related to the vulcanization system used. Ethylene-propylene rubber with dithiomorpholine and TMTD as vulcanization system, after soaking in superheated water at 125°C for 15 months, the mechanical properties change little, and the volume expansion rate is only 0.3%.
6. Electrical properties
Ethylene-propylene rubber has excellent electrical insulation properties and corona resistance, electrical properties better than or close to styrene butadiene rubber, chlorosulfonated polyethylene, polyethylene and cross-linked polyethylene.
7. Elasticity
Due to the non-polar substituent in the molecular structure of ethylene-propylene rubber, the intramolecular energy is low, and the molecular chain can maintain flexibility in a wide range, second only to natural rubber and butadiene rubber, and can be maintained at low temperatures.
8. Adhesion
Because of the lack of active groups in the molecular structure, ethylene propylene rubber has low cohesive energy, and the rubber compound is prone to blooming, resulting in poor self-adhesion and mutual viscosity.
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