The oil resistance of fluorine rubber is at the top level among rubber materials. The following is a detailed explanation from the aspects of performance characteristics, application performance, comparative analysis, influencing factors and improvement directions:
I. Characteristics of Oil Resistance Performance
Molecular structure advantage
The main chain of fluorine rubber is a carbon chain, and the side chains contain fluorine atoms (such as vinylidene fluoride - hexafluoropropylene copolymer). The electronegativity of fluorine atoms is extremely strong (4.0), and they form C-F bonds with high bond energy (485 kJ/mol) with carbon atoms, which is much higher than the C-C bonds (347 kJ/mol) in ordinary rubber.
Fluorine atoms tightly wrap around carbon chains, forming a dense "fluorinated layer", effectively blocking the penetration of oil molecules, which is equivalent to putting on a "protective armor" for rubber.
There are a wide range of oil-resistant types
Mineral oils: such as automotive lubricating oil and hydraulic oil. When fluorine rubber is soaked at 25℃ for 1000 hours, the volume change rate is less than 5% (while for ordinary nitrile rubber, it is over 20%).
Synthetic oils: such as aviation hydraulic oil (phosphate ester type), silicone oil, and fluorine rubber have stronger corrosion resistance and maintain stable performance at high temperatures.
Fuel: It has excellent resistance to gasoline and diesel. After being soaked at 23℃ for 70 hours, the tensile strength retention rate is > 90% (for ordinary rubber, it is < 70%).
Resistant to high-temperature oil environments
It can be used for a long time in high-temperature oil at 150-200℃. Some special fluorine rubbers (such as perfluoroether rubber) can work continuously at temperatures above 250℃. For instance, the oil seal of a diesel engine turbocharger can operate at a temperature of 220℃, and the fluorine rubber can run stably for over 10,000 hours.
Ii. Application Scenario Presentation
Automobile industry
Engine oil seal: It can withstand a temperature of 200℃ and an oil pressure of 1.5MPa. The service life of fluorine rubber oil seals can reach 100,000 kilometers (while that of ordinary rubber is only 30,000 to 50,000 kilometers).
Fuel system: The sealing parts of the fuel pump and fuel injector need to be resistant to gasoline corrosion. The gasoline penetration rate of fluorine rubber products should be less than 0.1 mg/cm²·day (the national standard requires less than 1 mg/cm²·day).
Aerospace
Hydraulic system: The temperature of the aircraft landing gear hydraulic oil (phosphate ester type) reaches 135℃, and the pressure is 35MPa. The leakage rate of fluorine rubber seals is less than 0.1cc /min (industry requirement is less than 1cc /min).
Fuel tank: Resistant to aviation kerosene corrosion, volume swelling rate < 2% (ordinary rubber > 10%).
Petrochemical industry
Oil well sealing: Resistant to crude oil and drilling fluid corrosion, with a temperature of 150℃ and a pressure of 50MPa. The service life of fluorine rubber O-rings is over 2 years (less than 6 months for ordinary rubber).
Valve sealing: Resistant to corrosion by sulfur-containing oil products, H? It can still operate normally at an S concentration of 500ppm.
Iii. Conclusion
The oil resistance of fluorine rubber far exceeds that of other rubber materials, especially in high-temperature, high-pressure and strongly corrosive oil environments, it has irreplaceable advantages. By optimizing the formula and process, its performance can be further enhanced to meet the strict requirements for sealing materials in high-end fields such as aerospace, automobiles, and petrochemicals. For application scenarios that pursue ultimate oil resistance and long service life, fluorine rubber is the best choice.
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