Fluorosilicone Fluid (Methyl Trifluoropropyl Polysiloxane, FMVQ): Fuel-Resistant and Solvent-Resistant Silicone for Aerospace and Industrial Applications
SEMITECH fluorosilicone fluid is the fuel-and-solvent-resistant silicone — methyl trifluoropropyl polysiloxane (FMVQ) with trifluoropropyl groups replacing methyl on alternate silicons. Provides 80–95% volume retention in jet fuel, hydraulic fluid, and aromatic solvents where standard PDMS swells 200–400%. Specialty grade for aerospace fuel system O-rings, military-spec gaskets, and chemical-process seals. 25 kg HDPE / 200 kg drum.
Contents
| FMVQ | 5–15% swell | 100–60,000 cP |
|---|---|---|
| ASTM designation | In jet fuel | Viscosity range |
Chemistry & Specifications
Methyl trifluoropropyl polysiloxane; pale-yellow viscous liquid; CF₃ groups provide fuel/solvent resistance.
Polymer structure [-Si(CH₃)(CH₂CH₂CF₃)-O-]ₙ, fluorine content 35–37%. Five viscosity tiers: 100 / 1,000 / 10,000 / 30,000 / 60,000 cP. Density 1.20–1.25 g/cm³ (significantly higher than PDMS at 0.97), flash point >250°C. Largely immiscible with standard PDMS, fully soluble in fluorinated solvents.
Fuel and Solvent Resistance: Why FMVQ Replaces PDMS
Trifluoropropyl groups provide hydrophobic, oleophobic, fluorophilic surface — minimal swelling in jet fuel, hydraulic fluid, aromatics.
Standard PDMS swells 200–400% in jet fuel. Fluorosilicone: 5–15% swell in Jet-A (168 hr at 70°C), 8–18% in hydraulic fluid, 15–25% in toluene.
- Aerospace fuel system O-rings — Jet-A/JP-8 resistance per AMS 7257, MIL-DTL-25988
- Military-spec gaskets — hydraulic + Skydrol resistance for combat aircraft
- Chemical-process seals — aromatic and chlorinated solvent resistance
- Automotive fuel injection — ethanol-blended fuel systems (E10, E85)
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Applications: Aerospace, Military, Automotive Fuel System, Chemical Process
Aerospace fuel system seals (largest), military hydraulic seals, automotive fuel injection, chemical process equipment seals.
Aerospace fuel system seals (largest) — O-rings, gaskets, fuel pump diaphragms meeting AMS 7257 / MIL-DTL-25988. Fluorosilicone uniquely combines fuel resistance, low-temperature flexibility (−55°C for flight), and high-temperature stability (+175°C in engine compartment). Military seals for combat aircraft and naval vessels. Automotive fuel injection where ethanol-blended fuels attack standard elastomers. Chemical-process seals for aromatic, chlorinated, and fluorinated solvents. Specialty: laser optics, semiconductor equipment, subsea applications.
Procurement, Storage and Quality Control
CoA per shipment; 25 kg HDPE / 200 kg drum; 24-month shelf life; non-flammable; cost premium ~5–8x methyl silicone.
CoA per batch: fluorine content (35.0–37.0% by XRF), viscosity (±10%), volatile fluorocyclic (≤2%), water (≤500 ppm), APHA (≤50). MOQ 25 kg. Lead time 4–6 weeks Asia, 6–8 weeks Europe/North America. Non-flammable (flash point >250°C). Shelf life 24 months sealed. Cost USD 25–35/kg (5–8x methyl silicone) — reflecting limited fluoromonomer supply and segregated production. Not classified as long-chain PFAS under current REACH framework. REACH-registered for industrial use.
Fluorosilicone Fluid Specification Sheet
SEMITECH stocked grades (100 / 1k / 10k / 30k / 60k cP); CoA per batch with fluorine-content verification.
| Property | Specification | Test Method |
|---|---|---|
| Chemical name | Methyl trifluoropropyl polysiloxane (FMVQ) | — |
| Polymer structure | [-Si(CH₃)(CH₂CH₂CF₃)-O-]ₙ | — |
| Fluorine content | 35.0–37.0% | X-ray fluorescence |
| Viscosity grades | 100 / 1,000 / 10,000 / 30,000 / 60,000 cP | Brookfield at 25°C |
| Volatile fluorocyclic content | ≤2% | GC |
| Water content | ≤500 ppm | Karl Fischer |
| APHA colour | ≤50 | ASTM D1209 |
| Density (25°C) | 1.20–1.25 g/cm³ | ASTM D1475 |
| Refractive index (25°C) | 1.385 | ASTM D1218 |
| Flash point | >250°C (closed cup) | ASTM D93 |
| Service temperature | −55°C to +175°C continuous | — |
| Jet fuel volume swell (168 hr at 70°C) | 5–15% | ASTM D471 |
| Hydraulic fluid swell | 8–18% | ASTM D471 |
| Solubility in fluorinated solvents | Fully miscible | — |
| Solubility in hydrocarbons | Partially miscible | — |
| Solubility in PDMS | Largely immiscible | — |
| Packaging | 25 kg HDPE jerrycan / 200 kg drum / 1 t IBC | — |
| Shelf life | 24 months sealed below 30°C | — |
FAQ
+Is fluorosilicone affected by EU PFAS restrictions?
No. The trifluoropropyl group (–CH₂CH₂CF₃) falls outside the C8+ perfluoroalkyl definition. Industrial use remains permitted. The broader PFAS landscape is evolving — ECHA may expand scope to shorter-chain fluorocarbons in 2026–2030.
+Fluorosilicone vs FKM (Viton) for fuel-resistant seals?
Different strengths. Fluorosilicone: low-temp flexibility to −55°C (FKM cracks below −20°C), broader temp range. FKM: lower swell (1–5% vs 5–15%), better aromatic resistance, lower cost. Use fluorosilicone for aerospace seals requiring low-temp flexibility; FKM for ground-based fuel systems above −20°C.
+How is fluorosilicone fluid converted to elastomer?
Compounded with fumed silica reinforcement (15–25%) and Pt or peroxide cure. Fluorosilicone-specific filler required — standard silicas are incompatible. Cured FMVQ: Shore A 50–80, tensile 8–14 MPa, elongation 200–400%.