Fluorinated ethylene propylene FEP
Copolymer of tetrafluoroethylene and hexafluoropropylene, (-CF2-CF2-)n units with -CF2-CF(CF3)- units · CAS 25067-11-2
FEP is a melt-processible copolymer of tetrafluoroethylene and hexafluoropropylene, sold by DuPont as Teflon FEP and by Daikin as NEOFLON FEP.
Evidence level
5 of 5
Flown or field-proven
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Recipe, share of the weight
- not statedTetrafluoroethylene
- not statedHexafluoropropylene
Best for
A chemically inert, electrically insulating and low-outgassing fluoropolymer that can be melt-processed into thin films, coatings and tubing.
Weakest at
Mechanical strength and ductility after long orbital exposure (Hubble retrieved specimens dropped to 0 to 25 percent elongation), and releasing hydrogen fluoride when processed above 250 degC.
Risk at a glance
- People No data. No hazard data recorded
- If it fails No data. No failure risks recorded
- Corrosion No data. No corrosion data recorded
Quick facts: FEP
| Property | Value | Basis |
|---|---|---|
| Density | 2.14 to 2.15 g/cm³ | 2 sourced values across conditions |
| Yield strength | 13.8 to 14.3 MPa | 1 sourced value |
| Tensile strength | 20 MPa | 1 sourced value |
| Melting point | 245 to 275 °C | 2 sourced values across conditions |
| Maximum service temperature | 204 °C | 1 sourced value |
What is the density of Fluorinated ethylene propylene (FEP)?
Fluorinated ethylene propylene (FEP) has a density of 2.14 to 2.15 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the melting point of Fluorinated ethylene propylene (FEP)?
Fluorinated ethylene propylene (FEP) has a melting point of 245 to 275 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the yield strength of Fluorinated ethylene propylene (FEP)?
Fluorinated ethylene propylene (FEP) has a yield strength of 13.8 to 14.3 MPa. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Fluorinated ethylene propylene (FEP)?
Fluorinated ethylene propylene (FEP) has a tensile strength of 20 MPa. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of Fluorinated ethylene propylene (FEP)?
Fluorinated ethylene propylene (FEP) has a maximum service temperature of 204 °C. The source and test conditions are listed in the properties table on this page.
What is Fluorinated ethylene propylene (FEP) used for?
Uses recorded in the sources include Wire and cable insulation; Pipe and valve linings and sleeves.
Why it exists
FEP keeps the chemical inertness and insulating behaviour of PTFE but can be melt-processed into thin films, coatings and tubing. On the MISSE 2 flight its atomic oxygen erosion yield was 2.00e-25 cm3/atom, and its dielectric constant at 1 MHz is 2.03.
Where it's used
Use
Wire and cable insulation, where the low dielectric constant and dissipation factor matter.
Use
Pipe and valve linings and sleeves in chemical plants.
Use
Thin films for spacecraft thermal blankets, where the MISSE 2 erosion yield and the Hubble embrittlement set the limits.
Recipe
Copolymer of tetrafluoroethylene and hexafluoropropylene, (-CF2-CF2-)n units with -CF2-CF(CF3)- units; CAS 25067-11-2
FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene. Its repeat units are CF2-CF2 from the first monomer and CF2-CF(CF3) from the second, with a small fraction of propylene-based units in the chain according to Wikipedia. Daikin and Chemours sell it as a pellet resin, and it is processed by melt extrusion or injection moulding.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Tetrafluoroethylene | not stated | Main backbone monomer; the -CF2-CF2- units give the chemical inertness and low friction of the chain. |
| Hexafluoropropylene | not stated | Second monomer; its pendant -CF3 groups break up the crystal structure, so FEP melts about 40 degC lower than PFA according to Wikipedia. |
Weight shares are as printed in the sources.
What it can do
Strength
FEP resists most chemicals, insulates well at high frequency, and melt-processes into thin films. It has a melting point of 255 degC and a 20 MPa tensile strength in the ASTM D 638 test.
How it compares
Among the MISSE 2 polymers FEP erodes slowly under atomic oxygen, at 2.00e-25 cm3/atom. It melts at about 255 degC and can be melt-processed, which PTFE cannot. Its tensile strength of 20 MPa and elongation of 300 percent are modest for a structural role.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | FEP | AF | PCTFE (CTFE, Kel-F) | ECTFE (Halar) | ETFE | PFA | PTFE | PVDF (Kynar) | PVF | PVF (white Tedlar) |
|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||||||
| Melting point, Teflon FEP 9495 | 255 °C4 | no data | 210 °C | 238 °C | 265 °C | 302 °C | no data | no data | no data | 185 °C |
| Melting point range, NEOFLON FEP NP-40 family | 245 °C5 | no data | 210 °C | 238 °C | 265 °C | 302 °C | no data | no data | no data | 185 °C |
| Physical and electrical | ||||||||||
| Density (MISSE 2 sample, ref 12) | 2.144 g/cm³2 | 2.146 g/cm³ | 2.133 g/cm³ | 1.68 g/cm³ | 1.74 g/cm³ | 2.138 g/cm³ | 2.17 g/cm³ | no data | 1.379 g/cm³ | 1.624 g/cm³ |
| Density (semi-finished FEP, ASTM D 792) | 2150 kg/m33 | 2.146 g/cm³ | 2.133 g/cm³ | 1.68 g/cm³ | 1.74 g/cm³ | 2.138 g/cm³ | 2.17 g/cm³ | no data | 1.379 g/cm³ | 1.624 g/cm³ |
| Other measurements | ||||||||||
| Atomic oxygen erosion yield, MISSE 2 flight | 2×10^-25 cm³/atom1 | 1.98×10^-25 cm³/atom | 8.31×10^-25 cm³/atom | 1.79×10^-24 cm³/atom | 9.61×10^-25 cm³/atom | 1.73×10^-25 cm³/atom | 1.42×10^-25 cm³/atom | 1.29×10^-24 cm³/atom | 3.19×10^-24 cm³/atom | 1.01×10^-25 cm³/atom |
| Maximum operating temperature | 204 °C6 | no data | 175 °C | 149 °C | 150 °C | 260 °C | 260 °C | no data | 107 °C | 107 °C |
| Tensile strength at break, Teflon FEP 9495 | 20 MPa7 | 26.9 MPa | 34 MPa | 7000 psi | 40 MPa | 21 MPa | no data | no data | 8 kpsi | 55 MPa |
| Elongation at break, Teflon FEP 9495 | 300 %8 | 17.1 % | 100 % | 200 % | 300 % | 300 % | no data | no data | 90 % | 90 % |
| Elongation at break, pristine FEP (Hubble test set) | 340 %9 | 17.1 % | 100 % | 200 % | 300 % | 300 % | no data | no data | 90 % | 90 % |
| Yield strength, pristine FEP (Hubble test set) | 13.8 MPa10 | 27.4 MPa | no data | no data | no data | 12 MPa | no data | no data | no data | no data |
| Flexural modulus, Teflon FEP 9495 | 520 MPa11 | 1.8 GPa | no data | no data | no data | 0.54 GPa | no data | 1655 MPa | no data | no data |
| Dielectric constant at 1 MHz | 2.03 -12 | 1.93 unitless | no data | 2.5 none | 2.6 dimensionless | 2 - | 2.1 dimensionless | no data | no data | 11 - |
| Dielectric strength, short time | 80 kV/mm13 | 2.1 kV/0.1 mm | no data | 500 V/mil | no data | 260 kV/mm | 30 kV/mm | no data | no data | 3.5 kV/mil |
| Dissipation factor at 1 MHz | 6×10^-4 -14 | 1×10^-4 unitless | no data | no data | no data | no data | no data | no data | no data | no data |
| Water absorption, 24 hour | 0.01 %15 | 0.01 % | no data | 0.1 % | no data | no data | no data | no data | 0.5 % | 0.5 % |
| Limiting oxygen index | 95 %16 | no data | no data | no data | no data | no data | > 95 % oxygen | no data | no data | no data |
| Melt flow index | 30 g/10min17 | no data | no data | no data | no data | 14 g/10min | no data | no data | no data | no data |
Why choose it, and why not
Good for
- Insulating wire and cable jackets, linings for chemical pipework, and low-outgassing films where chemical inertness and atomic oxygen resistance matter.
Watch out for
- Long orbital exposure embrittles FEP; the Hubble specimens reached 0 percent elongation. Above 250 degC it releases hydrogen fluoride, and it has low tensile strength for structural loads.
FEP is a practical, chemically inert insulator with good atomic oxygen resistance for its class, but its ductility falls off sharply after long exposure to thermal cycling and radiation, so it should be used as a thin, protected layer rather than a structural part.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Atomic oxygen erosion yield, MISSE 2 flight | Value printed in NASA Table I (MISSE 2 PEACE Polymers erosion yield data) as the measured MISSE 2 erosion yield; the paper cites refs 11 and 12 for the data | environment low Earth orbit, ISS MISSE 2 PEACE Polymers trayfluence 8.43e21 atoms/cm2 (4 year exposure)unit in source cm3/atom | — |
| 2 | Density (MISSE 2 sample, ref 12) | Density listed in NASA Table II (MISSE 2 PEACE Polymers density and fractional ash content), column Density, ref. 12 | sample MISSE 2 PEACE Polymers film | — |
| 3 | Density (semi-finished FEP, ASTM D 792) | Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Other Properties section | test standard ASTM D 792 | — |
| 4 | Melting point, Teflon FEP 9495 | Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Thermal Properties section | test standard ASTM D 3418 | — |
| 5 | Melting point range, NEOFLON FEP NP-40 family | Value printed in the Daikin safety data sheet, section 9.1, Melting point/freezing point line | grade NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 | — |
| 6 | Maximum operating temperature | Value printed in the infobox of the Wikipedia FEP article; it is a secondary summary, not a datasheet value | basis value in the infobox of the Wikipedia article | — |
| 7 | Tensile strength at break, Teflon FEP 9495 | Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section | test standard ASTM D 638 | — |
| 8 | Elongation at break, Teflon FEP 9495 | Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section | test standard ASTM D 638 | — |
| 9 | Elongation at break, pristine FEP (Hubble test set) | Value printed in NASA Table 3 (summary of strength test results), pristine rows, elongation column | sample pristine FEP specimens, Hubble Space Telescope test set (three specimens) | — |
| 10 | Yield strength, pristine FEP (Hubble test set) | Value printed in NASA Table 3, pristine rows, first (yield) strength column; the table header is garbled in the PDF text layer, so the column is read from its position | sample pristine FEP specimens, Hubble Space Telescope test set | — |
| 11 | Flexural modulus, Teflon FEP 9495 | Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section | test standard ASTM D 790 | — |
| 12 | Dielectric constant at 1 MHz | Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section | frequency 1 MHztest standard ASTM D 150 | — |
| 13 | Dielectric strength, short time | Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section | test standard ASTM D 149mode short time | — |
| 14 | Dissipation factor at 1 MHz | Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section | frequency 1 MHztest standard ASTM D 150 | — |
| 15 | Water absorption, 24 hour | Value printed in the Material Data Center property table for Teflon FEP 9495, Other Properties section | test standard ASTM D 570time 24 hours | — |
| 16 | Limiting oxygen index | Value printed in the Material Data Center property table for Teflon FEP 9495, Thermal Properties section | test standard ASTM D 2863 | — |
| 17 | Melt flow index | Value printed in the Material Data Center property table for Teflon FEP 9495, Processing section | temperature 372 °Cload 5 kgtest standard ASTM D 2116 | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Atomic oxygen in low Earth orbit (MISSE 2, about 4 years) | not rated | FEP erodes under atomic oxygen, but more slowly than most polymers on the MISSE 2 tray.1 |
| Hubble Space Telescope, long-duration exposure in low Earth orbit (outer MLI layer) | not rated | Retrieved FEP lost most of its stretch and became brittle, with cracks through the thickness.2 |
| Reactive chemicals and high temperature | not rated | FEP is inert to most chemicals, but elemental fluorine, molten alkali metals and chlorine tetrafluoride attack it.3 |
| Heating during processing or fire | not rated | Above 250 degC FEP gives off hydrogen fluoride and other toxic fluorinated compounds.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Atomic oxygen in low Earth orbit (MISSE 2, about 4 years) | Measured erosion yield of 2.00e-25 cm3/atom, printed in the same table as the predicted values for 40 polymers. | fluence 8.43e21 atoms/cm2 |
| 2 | Hubble Space Telescope, long-duration exposure in low Earth orbit (outer MLI layer) | The retrieved specimens reached 0 percent elongation in the SM2 LS group, against 340 to 390 percent for pristine FEP; the report attributes the damage to thermal cycling and deep-layer electron and proton radiation. | exposure long-duration exposure on Hubble, retrieved on the SM2 servicing mission |
| 3 | Reactive chemicals and high temperature | Daikin says FEP is completely inert to attack by most chemicals except at high temperature, and is susceptible to high-pressure elemental fluorine gas, molten alkali metals and chlorine tetrafluoride. | temperature high temperature |
| 4 | Heating during processing or fire | Daikin states that hydrogen fluoride and other toxic fluorinated compounds may be produced above 250 degC, and the SDS warns that toxic gases form during heating or in fire. | temperature above 250 °C |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
Workers who melt, extrude or mould FEP, because processing above 250…
Firefighters and anyone handling burning FEP, because fire produces…
Mission planners using FEP outer layers, because thermal cycling and…
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Long-duration exposure to space, with thermal cycling and radiation,… | Long-duration exposure to space, with thermal cycling and radiation, embrittles the film and cracks it, as seen on Hubble. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Surroundings | Excessive airborne powder can irritate the eyes, skin and upper airways, and smoking near the material can expose smokers to toxic gases. |
Handling and storage
- Process ovens and equipment in well-ventilated areas, and wear proper PPE; use colorants with heat stability above 400 degC.
Mitigations
- Ventilate processing areas and keep processing below the temperature at which hydrogen fluoride is produced.
Supply and geography
How common the raw materials are and where they come from.
Fluorspar (CaF2), the mineral feedstock for fluorine chemistry
Fluorspar is the mineral source of the hydrogen fluoride used to make fluoropolymers; USGS reports the primary feedstock for fluorine chemicals, including fluoropolymers, is aqueous HF.
- Top producers (2025)
- China, Mexico, Mongolia, South Africa, Vietnam
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: fep
spore_version: 0.2
family: fluoropolymers
name: Fluorinated ethylene propylene
abbreviation: FEP
role: melt-processible fluoropolymer for wire coating, linings and low-outgassing films
category: polymers
type: fluoropolymers
summary: FEP is a melt-processible copolymer of tetrafluoroethylene and hexafluoropropylene, sold by DuPont as Teflon FEP and by Daikin as NEOFLON FEP. It melts near 255 degC by ASTM D 3418 and is almost chemically inert. On the MISSE 2 flight it eroded under atomic oxygen at 2.00e-25 cm3/atom, and Hubble's retrieved FEP lost most of its stretch after long exposure in low Earth orbit.
best_for: A chemically inert, electrically insulating and low-outgassing fluoropolymer that can be melt-processed into thin films, coatings and tubing.
weakest_at: Mechanical strength and ductility after long orbital exposure (Hubble retrieved specimens dropped to 0 to 25 percent elongation), and releasing hydrogen fluoride when processed above 250 degC.
identity:
formula: Copolymer of tetrafluoroethylene and hexafluoropropylene, (-CF2-CF2-)n units with -CF2-CF(CF3)- units; CAS 25067-11-2
cas: 25067-11-2
source: daikin-fep-stewardship
where: Chemical Name and CAS Registry Number table; composition from Wikipedia FEP lead paragraph (copolymer of hexafluoropropylene and tetrafluoroethylene)
tags:
environments:
- low-earth-orbit
stresses:
- atomic-oxygen
- total-radiation-dose
- thermal-cycling
- vacuum-and-outgassing
applications:
- electronics-and-chips
- propulsion-and-tanks
properties:
- benchmark: atomic_oxygen_erosion_yield
label: Atomic oxygen erosion yield, MISSE 2 flight
value: 2.e-25
unit: cm3/atom
scope: material
conditions:
environment: low Earth orbit, ISS MISSE 2 PEACE Polymers tray
fluence: 8.43e21 atoms/cm2 (4 year exposure)
unit_in_source: cm3/atom
method: Value printed in NASA Table I (MISSE 2 PEACE Polymers erosion yield data) as the measured MISSE 2 erosion yield; the paper cites refs 11 and 12 for the data
status: flight
source: nasa-ao-tool
where: Table I, row Fluorinated ethylene propylene (FEP), column erosion yield
- benchmark: density
label: Density (MISSE 2 sample, ref 12)
value: 2.1443
unit: g/cm3
scope: material
conditions:
sample: MISSE 2 PEACE Polymers film
method: Density listed in NASA Table II (MISSE 2 PEACE Polymers density and fractional ash content), column Density, ref. 12
status: ground
source: nasa-ao-tool
where: Table II, row Fluorinated ethylene propylene (FEP), Density column
- benchmark: density
label: Density (semi-finished FEP, ASTM D 792)
value: 2150
unit: kg/m3
scope: material
conditions:
test_standard: ASTM D 792
method: Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Other Properties section
status: ground
source: mdc-fep-9495
where: Other Properties table, row Density
- benchmark: melting_point
label: Melting point, Teflon FEP 9495
value: 255
unit: degC
scope: material
conditions:
test_standard: ASTM D 3418
method: Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Thermal Properties section
status: ground
source: mdc-fep-9495
where: Thermal Properties table, row Melting Temperature
- benchmark: melting_point
label: Melting point range, NEOFLON FEP NP-40 family
value: 245
value_high: 275
unit: °C
scope: material
conditions:
grade: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105
method: Value printed in the Daikin safety data sheet, section 9.1, Melting point/freezing point line
status: ground
source: daikin-np40-sds
where: Section 9.1, Information on basic physical and chemical properties
- benchmark: max_service_temp
label: Maximum operating temperature
value: 204
unit: degC
scope: material
conditions:
basis: value in the infobox of the Wikipedia article
method: Value printed in the infobox of the Wikipedia FEP article; it is a secondary summary, not a datasheet value
status: ground
source: wiki-fep
where: Infobox, row Maximum operating temperature
- benchmark: ultimate_tensile_strength
label: Tensile strength at break, Teflon FEP 9495
value: 20
unit: MPa
scope: material
conditions:
test_standard: ASTM D 638
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
status: ground
source: mdc-fep-9495
where: Mechanical Properties table, row Tensile Strength
- benchmark: elongation
label: Elongation at break, Teflon FEP 9495
value: 300
unit: '%'
scope: material
conditions:
test_standard: ASTM D 638
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
status: ground
source: mdc-fep-9495
where: Mechanical Properties table, row Elongation at Break
- benchmark: elongation
label: Elongation at break, pristine FEP (Hubble test set)
value: 340
value_high: 390
unit: '%'
scope: material
conditions:
sample: pristine FEP specimens, Hubble Space Telescope test set (three specimens)
method: Value printed in NASA Table 3 (summary of strength test results), pristine rows, elongation column
status: ground
source: townsend-hst-fep
where: Table 3, pristine rows, Elongation (%) column
- benchmark: yield_strength
label: Yield strength, pristine FEP (Hubble test set)
value: 13.8
value_high: 14.3
unit: MPa
scope: material
conditions:
sample: pristine FEP specimens, Hubble Space Telescope test set
method: Value printed in NASA Table 3, pristine rows, first (yield) strength column; the table header is garbled in the PDF text layer, so the column is read from its position
status: ground
source: townsend-hst-fep
where: Table 3, pristine rows, Yield Strength (MPa) column
- benchmark: flexural_modulus
label: Flexural modulus, Teflon FEP 9495
value: 520
unit: MPa
scope: material
conditions:
test_standard: ASTM D 790
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
status: ground
source: mdc-fep-9495
where: Mechanical Properties table, row Flexural Modulus
- benchmark: dielectric_constant
label: Dielectric constant at 1 MHz
value: 2.03
unit: '-'
scope: material
conditions:
frequency: 1 MHz
test_standard: ASTM D 150
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
status: ground
source: mdc-fep-9495
where: Electrical Properties table, row Dielectric Constant, 1 MHz
- benchmark: dielectric_strength
label: Dielectric strength, short time
value: 80
unit: kV/mm
scope: material
conditions:
test_standard: ASTM D 149
mode: short time
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
status: ground
source: mdc-fep-9495
where: Electrical Properties table, row Dielectric Strength, Short Time
- benchmark: dissipation_factor
label: Dissipation factor at 1 MHz
value: 0.0006
unit: '-'
scope: material
conditions:
frequency: 1 MHz
test_standard: ASTM D 150
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
status: ground
source: mdc-fep-9495
where: Electrical Properties table, row Dissipation Factor, 1 MHz
- benchmark: moisture_absorption
label: Water absorption, 24 hour
value: 0.01
unit: '%'
scope: material
conditions:
test_standard: ASTM D 570
time: 24 hours
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Other Properties section
status: ground
source: mdc-fep-9495
where: Other Properties table, row Water Absorption, 24hr
- benchmark: limiting_oxygen_index
label: Limiting oxygen index
value: 95
unit: '%'
scope: material
conditions:
test_standard: ASTM D 2863
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Thermal Properties section
status: ground
source: mdc-fep-9495
where: Thermal Properties table, row Limiting Oxygen Index
- benchmark: melt_flow_index
label: Melt flow index
value: 30
unit: g/10min
scope: material
conditions:
temperature: 372 degC
load: 5 kg
test_standard: ASTM D 2116
method: Value printed in the Material Data Center property table for Teflon FEP 9495, Processing section
status: ground
source: mdc-fep-9495
where: Processing/Physical table, row Melt Flow Index, MFI
corrosion:
- environment: Atomic oxygen in low Earth orbit (MISSE 2, about 4 years)
headline: FEP erodes under atomic oxygen, but more slowly than most polymers on the MISSE 2 tray.
effect: Measured erosion yield of 2.00e-25 cm3/atom, printed in the same table as the predicted values for 40 polymers.
conditions:
fluence: 8.43e21 atoms/cm2
source: nasa-ao-tool
where: Table I, FEP row
rating: unknown
- environment: Hubble Space Telescope, long-duration exposure in low Earth orbit (outer MLI layer)
headline: Retrieved FEP lost most of its stretch and became brittle, with cracks through the thickness.
effect: The retrieved specimens reached 0 percent elongation in the SM2 LS group, against 340 to 390 percent for pristine FEP; the report attributes the damage to thermal cycling and deep-layer electron and proton radiation.
conditions:
exposure: long-duration exposure on Hubble, retrieved on the SM2 servicing mission
source: townsend-hst-fep
where: Section on tensile test results, Table 3
rating: unknown
- environment: Reactive chemicals and high temperature
headline: FEP is inert to most chemicals, but elemental fluorine, molten alkali metals and chlorine tetrafluoride attack it.
effect: Daikin says FEP is completely inert to attack by most chemicals except at high temperature, and is susceptible to high-pressure elemental fluorine gas, molten alkali metals and chlorine tetrafluoride.
conditions:
temperature: high temperature
source: daikin-fep-stewardship
where: Physical and Chemical Properties paragraph
rating: unknown
- environment: Heating during processing or fire
headline: Above 250 degC FEP gives off hydrogen fluoride and other toxic fluorinated compounds.
effect: Daikin states that hydrogen fluoride and other toxic fluorinated compounds may be produced above 250 degC, and the SDS warns that toxic gases form during heating or in fire.
conditions:
temperature: above 250 degC
source: daikin-fep-stewardship
where: Exposure Effects of Decomposition Products paragraph
rating: unknown
uses:
- application: electronics-and-chips
device: Wire and cable insulation
example: Daikin lists wire and cable coating films and sheets as the main use of its FEP molding materials, together with tubes and small parts.
source: daikin-fep-stewardship
where: Uses paragraph
- application: propulsion-and-tanks
device: Pipe and valve linings and sleeves
example: Daikin lists pipe and valve linings and sleeves among its typical FEP uses, for lining process piping that must resist aggressive chemicals.
source: daikin-fep-stewardship
where: Uses paragraph
risks:
hazards:
- text: The FEP resin is not classified under the CLP regulation and has no GHS pictograms or hazard statements in the Daikin SDS.
ghs: []
source: daikin-np40-sds
where: Section 2.1 Classification, and Section 2 hazard statements Not applicable
- text: Heating above 250 degC or fire releases hydrogen fluoride and other toxic fluorinated gases, which can cause serious lung irritation.
ghs: []
source: daikin-fep-stewardship
where: Exposure Effects of Decomposition Products paragraph
failure_risks:
- source: townsend-hst-fep
where: Section on tensile test results, Table 3
mode: Long-duration exposure to space, with thermal cycling and radiation,…
consequence: Long-duration exposure to space, with thermal cycling and radiation, embrittles the film and cracks it, as seen on Hubble.
side_effects:
- text: Excessive airborne powder can irritate the eyes, skin and upper airways, and smoking near the material can expose smokers to toxic gases.
source: daikin-fep-stewardship
where: Health and Environmental Effects paragraph
handling:
- text: Process ovens and equipment in well-ventilated areas, and wear proper PPE; use colorants with heat stability above 400 degC.
source: daikin-fep-stewardship
where: Processing Precautions paragraph
mitigations:
- text: Ventilate processing areas and keep processing below the temperature at which hydrogen fluoride is produced.
source: daikin-fep-stewardship
where: Processing Precautions and Exposure Effects paragraphs
supply:
- subject: Fluorspar (CaF2), the mineral feedstock for fluorine chemistry
abundance: Fluorspar is the mineral source of the hydrogen fluoride used to make fluoropolymers; USGS reports the primary feedstock for fluorine chemicals, including fluoropolymers, is aqueous HF.
producers:
- country: China
production: 6,000 thousand metric tons
year: 2025
- country: Mexico
production: 1,500 thousand metric tons
year: 2025
- country: Mongolia
production: 1,500 thousand metric tons
year: 2025
- country: South Africa
production: 410 thousand metric tons
year: 2025
- country: Vietnam
production: 160 thousand metric tons
year: 2025
source: usgs-fluorspar-2026
where: World Mine Production table, 2025 column; world total 10,000 thousand metric tons (rounded)
media: []
documents:
- title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (NASA/TM-2008-215490)
type: report
url: https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf
year: 2008
- title: Teflon FEP on-orbit degradation (Townsend and Hansen, NASA GSFC)
type: report
url: https://ntrs.nasa.gov/api/citations/19990040483/downloads/19990040483.pdf
year: 1999
- title: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 safety data sheet (Daikin, revision 08.03.2023)
type: sds
url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/FEP_NP-series/sds-np-40-E_20260723.pdf
year: 2023
- title: NEOFLON FEP NF Series safety data sheet (Daikin, revision 31.03.2023)
type: sds
url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer_Films/NEOFLON_FEP_NF_Series_DIL_EN_20260716.pdf
year: 2023
- title: 'Mineral Commodity Summaries 2026: Fluorspar (USGS)'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
year: 2026
- title: Teflon FEP 9495 property table (Material Data Center, Chemours)
type: datasheet
url: https://www.materialdatacenter.com/ms/en/Teflon/The+Chemours+Company/Teflon™+FEP+9495/6a4f05df/824
year: 2026
gaps:
- No ageing or ultraviolet test values for FEP were read in this run; the VUV and X-ray studies found in search were not opened for numbers.
- No humid-air or water-vapour corrosion result for FEP found; the water absorption value is the only moisture number.
- Atomic weights of C, F and H are not sourced in this run, so recipe parts carry no atomic_weight field.
- Monomer share in the FEP copolymer is not read from a source with a number; Wikipedia gives about 5 percent propylene component, which is not used as a value here.
- Erosion yield, melt flow index and limiting oxygen index use names that are not in spores/property-canon.yaml; they are listed here as new names.
- No PubChem GHS entry was opened; the hazard data rest on the Daikin and SDS documents.
- The Interstate Plastics FEP safety sheet returned HTTP 403 and was not read.
- No FEP-specific critical-mineral listing; fluorspar is in USGS MCS 2026 but its critical-mineral status is not stated in the page read.
sources:
nasa-ao-tool:
title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
id: NASA/TM-2008-215490
url: https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf
year: 2008
kind: report
license: public domain (NASA)
townsend-hst-fep:
title: On-Orbit Teflon FEP Degradation (Townsend and Hansen, NASA GSFC)
id: NTRS 19990040483
url: https://ntrs.nasa.gov/api/citations/19990040483/downloads/19990040483.pdf
year: 1999
kind: report
license: public domain (NASA)
daikin-np40-sds:
title: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 safety data sheet (Daikin)
id: Daikin SDS, revision 08.03.2023
url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/FEP_NP-series/sds-np-40-E_20260723.pdf
year: 2023
kind: datasheet
license: cited, not reproduced
daikin-nf-sds:
title: NEOFLON FEP NF Series safety data sheet (Daikin)
id: Daikin SDS, revision 31.03.2023
url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer_Films/NEOFLON_FEP_NF_Series_DIL_EN_20260716.pdf
year: 2023
kind: datasheet
license: cited, not reproduced
daikin-fep-stewardship:
title: Daikin-NEOFLON FEP product stewardship summary (env-pss-fep-001)
id: env-pss-fep-001 Rev. 0
url: https://www.daikinchemicals.com/library/pb_common/pdf/dai/env-pss-fep-001_Rev.0-002.pdf
year: 2021
kind: datasheet
license: cited, not reproduced
usgs-fluorspar-2026:
title: 'Mineral Commodity Summaries 2026: Fluorspar (U.S. Geological Survey)'
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
year: 2026
kind: report
license: public domain (USGS)
mdc-fep-9495:
title: Teflon FEP 9495 property data (Material Data Center, Chemours)
id: materialdatacenter FEP 9495
url: https://www.materialdatacenter.com/ms/en/Teflon/The+Chemours+Company/Teflon™+FEP+9495/6a4f05df/824
year: 2026
kind: datasheet
license: cited, not reproduced
wiki-fep:
title: Fluorinated ethylene propylene (Wikipedia)
id: Wikipedia, en
url: https://en.wikipedia.org/wiki/Fluorinated_ethylene_propylene
year: 2026
kind: web
license: CC BY-SA 4.0
license: CC-BY-4.0
updated: 2026-10-20T00:00:00.000Z
review:
status: draft
method: assistant
checked_values: 17
unreachable: 1
caveats: 1
note: 'Written from pages fetched in this run: 17 property values, 8 sources. Interstate Plastics sheet returned HTTP 403.'
story:
recipe:
line: FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene. Its repeat units are CF2-CF2 from the first monomer and CF2-CF(CF3) from the second, with a small fraction of propylene-based units in the chain according to Wikipedia. Daikin and Chemours sell it as a pellet resin, and it is processed by melt extrusion or injection moulding.
parts:
- name: Tetrafluoroethylene
monomer: C2F4
role: Main backbone monomer; the -CF2-CF2- units give the chemical inertness and low friction of the chain.
- name: Hexafluoropropylene
monomer: C3F6
role: Second monomer; its pendant -CF3 groups break up the crystal structure, so FEP melts about 40 degC lower than PFA according to Wikipedia.
risk_groups:
- title: Workers who melt, extrude or mould FEP, because processing above 250…
- title: Firefighters and anyone handling burning FEP, because fire produces…
- title: Mission planners using FEP outer layers, because thermal cycling and…
why: FEP keeps the chemical inertness and insulating behaviour of PTFE but can be melt-processed into thin films, coatings and tubing. On the MISSE 2 flight its atomic oxygen erosion yield was 2.00e-25 cm3/atom, and its dielectric constant at 1 MHz is 2.03.
uses:
- where: Use
line: Wire and cable insulation, where the low dielectric constant and dissipation factor matter.
- where: Use
line: Pipe and valve linings and sleeves in chemical plants.
- where: Use
line: Thin films for spacecraft thermal blankets, where the MISSE 2 erosion yield and the Hubble embrittlement set the limits.
can_do:
- label: Strength
line: FEP resists most chemicals, insulates well at high frequency, and melt-processes into thin films. It has a melting point of 255 degC and a 20 MPa tensile strength in the ASTM D 638 test.
compare: Among the MISSE 2 polymers FEP erodes slowly under atomic oxygen, at 2.00e-25 cm3/atom. It melts at about 255 degC and can be melt-processed, which PTFE cannot. Its tensile strength of 20 MPa and elongation of 300 percent are modest for a structural role.
compare_rows:
- label: Melting point
benchmark: melting_point
- label: Tensile strength
benchmark: ultimate_tensile_strength
- label: Dielectric constant at 1 MHz
benchmark: dielectric_constant
handling:
- Ventilate ovens and extrusion lines, wear PPE, and keep processing below the temperature at which hydrogen fluoride is produced. Use colorants with heat stability above 400 degC. Keep burning or overheated FEP away from people.
good_for:
- Insulating wire and cable jackets, linings for chemical pipework, and low-outgassing films where chemical inertness and atomic oxygen resistance matter.
watch_out:
- Long orbital exposure embrittles FEP; the Hubble specimens reached 0 percent elongation. Above 250 degC it releases hydrogen fluoride, and it has low tensile strength for structural loads.
verdict: FEP is a practical, chemically inert insulator with good atomic oxygen resistance for its class, but its ductility falls off sharply after long exposure to thermal cycling and radiation, so it should be used as a thin, protected layer rather than a structural part.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit | report | 2008 | 3 values | |
| On-Orbit Teflon FEP Degradation (Townsend and Hansen, NASA GSFC) | report | 1999 | 4 values | |
| NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 safety data sheet (Daikin) | datasheet | 2023 | 2 values | |
| NEOFLON FEP NF Series safety data sheet (Daikin) | datasheet | 2023 | 0 values | |
| Daikin-NEOFLON FEP product stewardship summary (env-pss-fep-001) | datasheet | 2021 | 9 values | |
| Mineral Commodity Summaries 2026: Fluorspar (U.S. Geological Survey) | report | 2026 | 1 value | |
| Teflon FEP 9495 property data (Material Data Center, Chemours) | datasheet | 2026 | 11 values | |
| Fluorinated ethylene propylene (Wikipedia) | web | 2026 | 1 value |