ePTFE
also Gore-Tex
A microporous, biaxially or uniaxially stretched form of PTFE with a fibrous node-fibril microstructure, used for gaskets, membranes and filtration media where compressibility, sealing conformability or gas-permeable/liquid-impermeable barrier properties are required.
Reference datasheet — ePTFE is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
ePTFE grades and fills
ePTFE is supplied in 5 conditions, soft to hard.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Carbon-filled / antistatic expanded PTFE | Carbon-black or carbon-fiber loaded ePTFE for static dissipation in solvent/fuel service and for fuel-cell gas-diffusion or electrode substrates. | 5 | 10 | 80 | 50 Shore D |
uniaxially expanded ePTFE cord / tape form-in-place sealant | Pick for large, warped, glass-lined or FRP flanges and manway covers where a cut gasket cannot conform — the cord is laid in place and crushed to shape. | 6 | 25 | 120 | 42 Shore D |
mineral-filled (barium sulfate / silica) expanded PTFE sheet | Use where cold flow / creep relaxation of pure ePTFE is unacceptable: mineral filler raises density and stress-retention at the cost of some conformability. | 12 | 100 | 50 Shore D | |
ePTFE membrane laminated to PET/PPS/glass scrim (filter media) | Choose for surface-filtration baghouse and HEPA/ULPA media: the ePTFE layer gives >99.99% capture and easy dust release, backing carries the mechanical load. | 12 | 30 | 60 | |
microporous ePTFE membrane / breathable film (Gore-Tex type) | Choose for waterproof-breathable laminates, vents, sterile barrier and 0.02–5 µm liquid/gas microfiltration; very thin (5–100 µm) with strong machine-direction orientation. | 40 | 120 |
Supply forms, finishes and certifications
Ways ePTFE is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
EXP-SHEETDefault | Biaxially expanded unfilled ePTFE gasket sheet | Supply form |
FIBER | Expanded PTFE fiber / yarn and braided packing | Supply form |
TAPE-TSEAL | Stretched (unsintered) PTFE thread-seal tape | Supply form |
MED | Medical / implantable grade ePTFE | Certification |
What is ePTFE?
A microporous, biaxially or uniaxially stretched form of PTFE with a fibrous node-fibril microstructure, used for gaskets, membranes and filtration media where compressibility, sealing conformability or gas-permeable/liquid-impermeable barrier properties are required. ePTFE has a density of 0.7 g/cm³ (0.0253 lb/in³), lighter than 83% of polymer grades. Its glass-transition temperature is 126°C (259 °F). ePTFE has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 200% and the elastic modulus is 0.2 GPa (0.029 Msi).
What is ePTFE used for?
- Gasketing sheet/tape for flanges
- Membrane filters and vents
- Vascular grafts and medical implants
- Sealant cord for irregular flanges
Advantages
- Good corrosion resistance — 98/100, better than 99% of polymer grades
- High service temperature — 260°C (500 °F), better than 97% of polymer grades
- Low moisture uptake — 0.01%, better than 97% of polymer grades
- Good UV / weathering resistance — 92/100, better than 93% of polymer grades
- Forms and bends easily — 90/100, better than 91% of polymer grades
Limitations
- High embodied carbon — 13 kg CO₂/kg, worse than 93% of polymer grades
- Poor heat conductor — 0.08 W/m·K (0.0462 BTU/hr·ft·°F), worse than 83% of polymer grades
ePTFE properties
Typical room-temperature values; bars are the position among polymer grades.
Physical4
ePTFE has a density of 0.7 g/cm³ (0.0253 lb/in³), lighter than 83% of polymer grades. Its glass-transition temperature is 126°C (259 °F).
Mechanical7
ePTFE has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 200% and the elastic modulus is 0.2 GPa (0.029 Msi).
Thermal8
ePTFE is rated for continuous service to 260°C (500 °F). It conducts heat at 0.08 W/m·K (0.0462 BTU/hr·ft·°F), worse than 83% of polymer grades. Thermal expansion is 110 µm/m·K (61.1 µin/in·°F).
Electrical6
ePTFE is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹⁶ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (98/100), better than 99% of polymer grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of ePTFE takes about 250 MJ of energy and emits 13 kg of CO₂ — more than 92% of polymer grades. Typical recycled content is 0%.
Manufacturability4
ePTFE's machinability is good (55/100, worse than 64% of polymer grades); weldability poor (20/100); formability excellent (90/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. ePTFE is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ePTFE
Is ePTFE easy to machine?
Do not turn or mill porous sheet — die-cut, water-jet, slit or ultrasonically cut; use sharp steel-rule dies and back the material to avoid crushing and edge densification.
Can ePTFE be welded?
Not melt-weldable in the usual sense; joints are made by lap-and-sinter above 340 °C, PFA/FEP film bonding, adhesive-backed overlaps or skiving-and-clamping.
Can ePTFE be formed, bent or molded?
Made by paste extrusion/calendering of fine-powder PTFE plus lubricant, lubricant removal, then uniaxial or biaxial stretching at 200–330 °C and optional amorphous locking (sinter) above 340 °C; final parts are cut or laminated rather than molded.
ePTFE chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| processing lubricant (isoparaffin naphth16–25% added for paste extrusion, volatilized before/during expansion | 0 – 0.1 | 0 |
| barium sulfate / silica filleronly in filled (FILLED-MIN) gasket grades | 0 – 40 | 0 |
| carbon black / carbon fiberonly in conductive/antistatic grades | 0 – 20 | 0 |
| PTFE (tetrafluoroethylene homopolymer)fine-powder (paste-extrusion) PTFE resin per ASTM D4895; ePTFE contains no plasticizer after lubricant removal | ≥ 95 (balance) |
What surface finishes work on ePTFE?
No paint or plating adheres without corona/plasma or sodium-etch pretreatment; typical finishing is adhesive backing (PSA strip), PFA edge sealing, scrim lamination, or hydrophobic/oleophobic surface treatment for vents.
Equivalent designations
Standards and trade names that resolve to ePTFE in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Gore-Tex
How much does ePTFE cost?
ePTFE is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ePTFE — frequently asked
What is ePTFE used for?
ePTFE is typically used for gasketing sheet/tape for flanges, membrane filters and vents, vascular grafts and medical implants and sealant cord for irregular flanges. In short: most conformable PTFE gasket; lowest-density PTFE form; cut, not machined.
What is the tensile strength of ePTFE?
ePTFE has a typical tensile strength of 15 MPa (2.18 ksi) — weaker than 74% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is ePTFE easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Do not turn or mill porous sheet — die-cut, water-jet, slit or ultrasonically cut; use sharp steel-rule dies and back the material to avoid crushing and edge densification.
Can ePTFE be welded?
Not readily — weldability is rated poor (20/100). Not melt-weldable in the usual sense; joints are made by lap-and-sinter above 340 °C, PFA/FEP film bonding, adhesive-backed overlaps or skiving-and-clamping.
What surface finishes work on ePTFE?
No paint or plating adheres without corona/plasma or sodium-etch pretreatment; typical finishing is adhesive backing (PSA strip), PFA edge sealing, scrim lamination, or hydrophobic/oleophobic surface treatment for vents.
Can ePTFE be formed, bent or molded?
Made by paste extrusion/calendering of fine-powder PTFE plus lubricant, lubricant removal, then uniaxial or biaxial stretching at 200–330 °C and optional amorphous locking (sinter) above 340 °C; final parts are cut or laminated rather than molded.
What is the maximum service temperature of ePTFE?
ePTFE is rated for continuous use to about 260°C (500 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does ePTFE cost?
ePTFE is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D4895 — PTFE Resin Produced from Dispersion (fine powder) — ASTM International (2018)
- ASTM F36 / F38 — Compressibility & Creep Relaxation of Gasket Materials — ASTM International (2020)
- ASTM F104 — Classification System for Nonmetallic Gasket Materials — ASTM International (2019)
- ASTM D882 / D1708 — Tensile Properties of Thin Plastic Sheeting — ASTM International (2018)
- Expanded PTFE gasket sheet, joint sealant and membrane datasheets — W. L. Gore & Associates / Donaldson / Sumitomo Electric (Poreflon) (2023)
- Engineered Materials Handbook, Vol. 2: Engineering Plastics (PTFE section) — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.