Question 1: What is the difference between fluorosilicone oil and ordinary silicone oil? Why is it indispensable in fuel and solvent environments?

Answer: Fluorosilicone oil is a type of modified silicone oil in which a γ-trifluoropropyl (–CH₂CH₂CF₃) group is introduced into the side chain of the polysiloxane backbone. It is commonly available in three reactive forms: hydroxyl-terminated (MY 25O), hydrogen-terminated (MY 25H), and vinyl-terminated (MY 25V). Its essential difference from ordinary methyl silicone oil lies in the medium resistance brought by "polar fluorine atoms":

Ordinary methyl silicone oil will swell significantly or even be extracted and fail in non-polar fuels, lubricating oils, and aromatic solvents; after introducing trifluoropropyl groups, it remains stable against aliphatic/aromatic fuels, mineral lubricants, and hydraulic fluids at both ambient and elevated temperatures. It is currently the only non-polar elastomer raw material system capable of long-term operation in fuel media at −68 to 232°C;

Simultaneously, it retains all the advantages of the siloxane backbone: low viscosity-temperature coefficient, low surface tension, high flash point, and low pour point. It can be used for long periods at −50°C to 250°C and exhibits chemical and physiological inertness.

According to general industry standards, the value of fluorosilicone oil lies not in being "cheap," but in its ability to withstand media that ordinary silicone oil cannot. When selecting a grade, first consider the fluorine content (homopolymers can reach 100%, copolymers can be adjusted to 10%~90%), and then check if the viscosity and terminal functional groups match the downstream curing system.

Question 2: What are the actual levels of oil and cold resistance? Can it replace Fluorocarbon Rubber (FKM)?
Answer: Let's look at several scenarios (based on measured parameters of commercial products):

Scenario	Key Performance	Data Source
Liquid Fluorosilicone Rubber (Injection Molded Parts)	Volume change in Dextron III (125°C × 168h): 1.11.2%; in IRM903 (150°C × 168h): 2.02.2%; in Biodiesel RME: 3.1~3.2%	MY FLSR3440 / 3460
Aviation Kerosene / General Fuel Seals	Volume change in JP-3 Jet Fuel (23°C × 168h): 4.9~5.1%; Compression set (177°C × 22h) after secondary curing: only 46%	MY FLSR3400 Series
General Compression/Extrusion Fluorosilicone Rubber	Volume swell in Fuel C (25°C / 72h): +20%; Heat aging at 200°C × 72h results in hardness increase of only +3A, and tensile strength/elongation decrease of approx. 20%/21%	MY FHTV3260
Fluorosilicone Raw Rubber for Wide Temperature Ranges	Operating temperature range: −60°C to 200°C; Brittle temperature can reach −85°C (while general FKM is only −30°C); Physical properties remain almost unchanged after 500h immersion in methanol gasoline systems	MY 3110-F
High-Temperature Limit Comparison	Decomposition temperature is approx. 300°C; Long-term operating temperature is −50 to 250°C; Heat resistance is lower than ordinary silicone rubber; Above 300°C, it releases toxic gases, requiring iron/titanium/rare earth heat stabilizers for improvement	Industry Public Data

Conclusion: Replacing Fluorocarbon Rubber (FKM) depends on conditions—fluorosilicone is significantly superior in the cross-condition of "low temperature + fuel/solvent": below −50°C, FKM becomes hard and loses elasticity, while fluorosilicone rubber maintains elasticity. Additionally, its swelling resistance in methanol gasoline is far lower than that of FKM, making it suitable for aviation integral tank seals, automotive oil seal diaphragms, and fuel pump diaphragms. However, when comparing pure high-temperature resistance and strong corrosive media, FKM still has the upper hand (fluorosilicone tops out at around 250°C and decomposes into toxic gas above 300°C). Two points must also be reminded to customers: ① Fluorosilicone rubber is a difficult-to-bond material with low surface energy; secondary bonding requires plasma or primer treatment; ② The compound will structure and the gel content will rise after storage; it must be moderately re-milled before use, but excessive re-milling will cause stickiness and scrapping. All replacement conclusions should be verified by sample testing.

Modified Platinum Catalyst, plz check MY 8141-8149