Important characteristics of fluorosilicone rubber
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Oil resistance, solvent resistance, and chemical resistance
Compared with methyl vinyl silicone rubber, fluorosilicone rubber has extremely excellent oil resistance, solvent resistance, and chemical resistance. Even compared with fluororubber, its oil resistance and solvent resistance are also good. After immersion in the same medium, temperature, and time, it shows excellent durability. It can be said that fluorosilicone rubber is the only elastomer that is resistant to non-polar media at -68°C to 232°C.
The gasoline resistance of fluorosilicone rubber containing methanol is also relatively good. Even in a gasoline/methanol (85 vol%/15 vol%) mixed system, the hardness, tensile strength, and volume change of its vulcanizate are very small. After a long immersion test of 500 hours, the physical properties hardly change.
Heat resistance
The high-temperature decomposition of fluorosilicone rubber is the same as that of silicone rubber, that is, side chain oxidation, main chain fracture, side chain thermal decomposition, and various complex reactions. Since the decomposition products can also cause main chain fracture, the heat resistance is usually worse than that of silicone rubber. Oxidative aging has begun at a temperature of 200°C. However, by adding a small amount of heat stabilizers such as iron, titanium, and rare earth oxides, it can be significantly improved. Even at a high temperature of 250°C, it has sufficient heat resistance. The influence of temperature on fluorosilicone rubber is greater than that on silicone rubber but smaller than that on fluororubber. Foreign countries have also studied the service life of fluorosilicone rubber under the conditions of 150°C×2000h, 175°C×5000h, and 200°C×4000h. The result is second only to methyl vinyl silicone rubber.
Cold resistance
Like ordinary silicone rubber, fluorosilicone rubber has good low-temperature performance. Since fluorosilicone rubber is a linear polymer composed mainly of flexible Si-O chains, its low-temperature characteristics are better than those of fluororubber with a C-C main chain. Among them, fluorosilicone rubber (LS-2370U) has better low-temperature characteristics, with a brittle temperature as low as -89°C, while ordinary fluororubber is about -30°C.
Electrical properties and radiation resistance
The electrical properties of fluorosilicone rubber are similar to those of ordinary silicone rubber. What is particularly valuable is that there is very little change under harsh conditions such as high temperature, low temperature, humidity, oil, solvent, chemicals, and ozone. The radiation resistance of fluorosilicone rubber is not outstanding, but its radiation aging resistance is better than that of methyl vinyl silicone rubber.
Physical and mechanical properties
Like ordinary silicone rubber, the mechanical strength (especially tear strength) of vulcanized fluorosilicone rubber is relatively low. Therefore, improving and enhancing the strength of fluorosilicone rubber is also an important research topic.
Other characteristics
The weather resistance of fluorosilicone rubber is very excellent. Even after being exposed for 5 years, it still maintains good performance. Ozone is one of the gases most generated during the aging of elastomers, but no cracks or fissures are found in fluorosilicone rubber after dynamic or static tests.
In addition, the mildew resistance, physiological inertness, and anticoagulant properties of fluorosilicone rubber are also very good.
