Hexcel HexTow IM7 carbon fibre IM7
C (PAN-based carbon fibre, 95.0% carbon content per the Hexcel datasheet)
HexTow IM7 is Hexcel's intermediate-modulus, PAN-based carbon fibre, supplied as 12K continuous tows.
Evidence level
2 of 5
Lab-measured
- 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
- C not statedCarbon
Best for
Structural composites that need more stiffness and strength than a standard-modulus fibre such as AS4 (Hexcel selector guide)
Weakest at
Low strain at failure (1.8% per Hexcel), and no fibre-only compression, fatigue or space-exposure data in the sources read
Risk at a glance
- People None found. Not classified as hazardous in the SDSs we checked
- If it fails Moderate. Brittle fracture at low strain
- Corrosion Low. Hexcel gives one year of constant properties for unsized fibre and five years for GP or GS sized fibre, if stored indoors below 35°C and below 50% relative humidity.
Quick facts: IM7
| Property | Value | Basis |
|---|---|---|
| Density | 1.78 g/cm³ | 1 sourced value |
| Tensile strength | 4,501 to 6,170 MPa | 5 sourced values across conditions |
| Young's modulus | 231 to 304 GPa | 5 sourced values across conditions |
| Thermal conductivity | 5.4 W/m-ºK | 1 sourced value |
| Thermal expansion (CTE) | -0.64 ppm/ºC | 1 sourced value |
| Specific heat | 879 J/(kg·K) | 1 sourced value |
What is the density of Hexcel HexTow IM7 carbon fibre?
Hexcel HexTow IM7 carbon fibre has a density of 1.78 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Hexcel HexTow IM7 carbon fibre?
Hexcel HexTow IM7 carbon fibre has a thermal conductivity of 5.4 W/m-ºK. The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Hexcel HexTow IM7 carbon fibre?
Hexcel HexTow IM7 carbon fibre has a coefficient of thermal expansion of -0.64 ppm/ºC. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Hexcel HexTow IM7 carbon fibre?
Hexcel HexTow IM7 carbon fibre has a tensile strength of 4,501 to 6,170 MPa. The range covers 5 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 Young's modulus of Hexcel HexTow IM7 carbon fibre?
Hexcel HexTow IM7 carbon fibre has a Young's modulus of 231 to 304 GPa. The range covers 5 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 Hexcel HexTow IM7 carbon fibre used for?
Uses recorded in the sources include Aerospace structures using an aerospace-grade fibre; Formula 1 cars, competition racing boats and high-performance cars.
Why it exists
Carbon fibre is a fine carbon filament used as reinforcement in composite parts. HexTow IM7 is Hexcel's intermediate-modulus carbon fibre, made from PAN and supplied as 12K tows. Hexcel's datasheet prints a typical tensile strength of 5670 MPa and a tensile modulus of 276 GPa for the fibre. Hexcel sells IM7 for weaving, prepregging, filament winding, braiding and pultrusion, so it is an input to composite parts rather than a finished part.
Where it's used
Aerospace structures
Hexcel says IM7-G 12K (0.25%) carbon fiber has been qualified to NMS 818 Carbon Fiber Specification (NCAMP). That lets a buyer call out an industry standard, aerospace grade fibre without writing its own specification. We did not confirm that qualification in an NCAMP document.
Racing cars and boats
Hexcel's selector guide says its standard and intermediate modulus fibres are selected for Formula 1 cars, competition racing boats and high-performance cars.
Recipe
C (PAN-based carbon fibre, 95.0% carbon content per the Hexcel datasheet)
HexTow IM7 is a continuous, PAN-based carbon fibre. A polyacrylonitrile (PAN) precursor is heated to drive off non-carbon atoms, which leaves carbon fibre, and Hexcel then surface treats and sizes the yarn (Wikipedia; Hexcel datasheet).
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Carbon C | not stated | The fibre itself. Hexcel prints a carbon content of 95.0% for IM7; the sizing and other elements make up the balance, and the datasheet does not itemise them. |
Weight shares are as printed in the sources.
What it can do
Strength
Carry a typical tensile strength of 5670 MPa at a density of 1.78 g/cm3, per Hexcel's IM7 datasheet.
Give a stiffer fibre than AS4
a tensile modulus of 276 GPa against 231 GPa for AS4, per Hexcel's selector guide.
Strength
Be woven, prepregged, filament wound, braided or pultruded, as Hexcel recommends for the fibre.
How it compares
Against Hexcel's standard-modulus AS4 fibre, IM7 has a typical tensile strength of 5670 MPa against 4501 MPa, and a tensile modulus of 276 GPa against 231 GPa (Hexcel selector guide). Against the newer IM8, the IM8 datasheet prints 6170 MPa and 304 GPa, so IM8 is stronger and stiffer. The IM6 datasheet prints 5860 MPa and 279 GPa, and the AS7 datasheet, which describes AS7 as high strain, prints 4930 MPa and 243 GPa. Hexcel calls its performance values representative, not guaranteed, and the figures come from separate datasheets rather than one test series.
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. Compare every grade in the family.
| Measurement | IM7 |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity, HexTow IM7 yarnManufacturer value on Hexcel's datasheet | 5.4 W/m-ºK5 |
| Specific heat, HexTow IM7 yarnManufacturer value on Hexcel's datasheet | 0.21 cal/g-°C7 |
| Physical and electrical | |
| Density, HexTow IM7 fibreManufacturer typical value on Hexcel's datasheet | 1.78 g/cm³3 |
| Weight per length, 12K HexTow IM7 towManufacturer typical value on Hexcel's datasheet | 0.446 g/m |
| Other measurements | |
| Tensile strength, HexTow IM7 fibre (typical) | 5670 MPa1 |
| Tensile modulus, HexTow IM7 fibre (typical) | 276 GPa2 |
| Ultimate elongation at failure, HexTow IM7 fibreManufacturer typical value on Hexcel's datasheet | 1.8 % |
| Carbon content, HexTow IM7 fibreManufacturer typical value on Hexcel's datasheet | 95 % |
| Filament diameter, HexTow IM7 fibreManufacturer typical value on Hexcel's datasheet | 5.2 microns4 |
| Coefficient of thermal expansion, HexTow IM7 yarnManufacturer value on Hexcel's datasheet | -0.64 ppm/ºC6 |
| Comparison - tensile strength, HexTow IM8 fibre (typical) | 6170 MPa8 |
| Comparison - tensile modulus, HexTow IM8 fibre (typical) | 304 GPa9 |
| Comparison - tensile strength, HexTow IM6 fibre (typical, 12K) | 5860 MPa10 |
| Comparison - tensile modulus, HexTow IM6 fibre (typical) | 279 GPa11 |
| Comparison - tensile strength, HexTow AS7 fibre (typical) | 4930 MPa12 |
| Comparison - tensile modulus, HexTow AS7 fibre (typical) | 243 GPa13 |
| Comparison - tensile strength, HexTow AS4 fibre (typical) | 4501 MPa14 |
| Comparison - tensile modulus, HexTow AS4 fibre (typical) | 231 GPa15 |
Why choose it, and why not
Good for
- Structures that need more stiffness and strength than a standard-modulus fibre: IM7 gives 276 GPa against 231 GPa for AS4.
- Aerospace programmes that specify a qualified fibre: Hexcel says IM7-G 12K (0.25%) is qualified to NMS 818, pending independent confirmation.
Watch out for
- Low strain at failure: IM7 breaks at 1.8% elongation according to Hexcel.
- Ageing: Hexcel's storage guidance gives one year for unsized fibre and five years for GP or GS sized fibre; beyond that the fibre may process badly.
- Typical values, not guarantees: Hexcel calls its performance figures representative.
In Hexcel's range, IM7 is the stiffer and stronger choice over AS4, and Hexcel says it is qualified to NMS 818 for aerospace work. Confirm that qualification with NCAMP before you rely on it.
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 | Tensile strength, HexTow IM7 fibre (typical) | Manufacturer typical value printed on Hexcel's IM7 product data sheet | form continuous HexTow IM7 towbasis typical fibre property; Hexcel calls its performance values representative, not guaranteed | The same row prints 820 ksi in U.S. units. |
| 2 | Tensile modulus, HexTow IM7 fibre (typical) | Manufacturer typical value on Hexcel's datasheet; modulus is a chord between 6000 and 1000 as printed on the datasheet | form continuous HexTow IM7 towtest basis printed as Tensile Modulus (Chord 6000-1000); the same row prints 40.0 Msi | — |
| 3 | Density, HexTow IM7 fibre | — | form continuous HexTow IM7 towbasis typical fibre property | The same row prints 0.0643 lb/in3 in U.S. units. The selector guide prints 1.78 g/cm3 for IM7 too. |
| 4 | Filament diameter, HexTow IM7 fibre | — | form individual filament in the towbasis typical fibre property | The same row prints 0.203 mil in U.S. units. |
| 5 | Thermal conductivity, HexTow IM7 yarn | — | form yarn/towdirection not stated in the datasheet | The same row prints 3.12 Btu/hr-ft-ºF in U.S. units. |
| 6 | Coefficient of thermal expansion, HexTow IM7 yarn | — | form yarn/towdirection not stated in the datasheet | The same row prints -0.36 ppm/ºF in U.S. units. |
| 7 | Specific heat, HexTow IM7 yarn | — | form yarn/tow | The same row prints 0.21 Btu/lb-°F in U.S. units. |
| 8 | Comparison - tensile strength, HexTow IM8 fibre (typical) | Manufacturer typical value on Hexcel's IM8 product data sheet | form continuous HexTow IM8 towbasis typical fibre property; comparator, not IM7 | The same row prints 895 ksi in U.S. units. |
| 9 | Comparison - tensile modulus, HexTow IM8 fibre (typical) | Manufacturer typical value on Hexcel's IM8 product data sheet | form continuous HexTow IM8 towtest basis printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7 | — |
| 10 | Comparison - tensile strength, HexTow IM6 fibre (typical, 12K) | Manufacturer typical value on Hexcel's IM6 product data sheet | form 12K HexTow IM6 towbasis typical fibre property; comparator, not IM7 | The same row prints 850 ksi in U.S. units. |
| 11 | Comparison - tensile modulus, HexTow IM6 fibre (typical) | Manufacturer typical value on Hexcel's IM6 product data sheet | form continuous HexTow IM6 towtest basis printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7 | — |
| 12 | Comparison - tensile strength, HexTow AS7 fibre (typical) | Manufacturer typical value on Hexcel's AS7 product data sheet | form continuous HexTow AS7 towbasis typical fibre property; comparator, not IM7 | The same row prints 715 ksi in U.S. units. |
| 13 | Comparison - tensile modulus, HexTow AS7 fibre (typical) | Manufacturer typical value on Hexcel's AS7 product data sheet | form continuous HexTow AS7 towtest basis printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7 | — |
| 14 | Comparison - tensile strength, HexTow AS4 fibre (typical) | Manufacturer typical value in Hexcel's selector guide | form continuous HexTow AS4 towbasis tow tensile strength from the aerospace-grade table; comparator, not IM7 | The same row prints 650 ksi. |
| 15 | Comparison - tensile modulus, HexTow AS4 fibre (typical) | Manufacturer typical value in Hexcel's selector guide | form continuous HexTow AS4 towbasis tow tensile modulus from the aerospace-grade table; comparator, not IM7 | The same row prints 33.5 Msi. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Storage of carbon fibre in warm or humid conditions (ageing rather than corrosion) | low | Hexcel gives one year of constant properties for unsized fibre and five years for GP or GS sized fibre, if stored indoors below 35°C and below 50% relative humidity.1 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Storage of carbon fibre in warm or humid conditions (ageing rather than corrosion) | Hexcel's storage guidance, which covers HexTow carbon fibre in general and does not list IM7 separately, says unsized fibre keeps its tow tensile strength, tow tensile modulus, tow tensile elongation and fibre density for at least one year from manufacture, and GP and GS sized fibre keeps them for at least five years. Fibre stored at high temperature or high humidity, or beyond the recommended time, may process badly, and Hexcel advises checking its processing (resin wet-out and spreadability) before use. | storage indoors, in original containers, below 35°C (95°F) and below 50% RH; shrink wrap kept on until useexposure high temperature or high humidity, or storage beyond the recommended time |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The Hexcel fabric SDS and the Rave thread SDS classify carbon fibre as not hazardous. Both describe dust, and the Hexcel SDS notes mild irritation.
- Dust
- Fine dust clouds may form explosive mixtures with air, per the Hexcel fabric SDS. The Rave SDS advises avoiding dust.
- Skin and eyes
- Hexcel's SDS notes mild, temporary mechanical irritation of the eyes and skin.
- Exposure limit
- The Rave SDS gives an EU occupational exposure limit of 10 mg/m3 TWA for carbon (C) fibres.
If a part fails
Breakage at low strain is the main mechanical risk. The sources do not give a failure test for finished parts.
- Strain at failure
- Hexcel gives IM7 an ultimate elongation at failure of 1.8%, so the fibre can break after only a small stretch.
Storage and handling
- Storage
- Hexcel says to store it indoors, below 35°C and below 50% relative humidity.
- Age
- Hexcel gives one year for unsized fibre and five years for GP or GS sized fibre.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Brittle fracture at low strainmoderate severity | Tensile loading of the fibre to failureHexcel lists an ultimate elongation at failure of 1.8% for IM7, so the fibre breaks after only a small stretch. |
| Loss of processing quality after poor storagelow severity | Storage above 35°C or above 50% relative humidity, or storage beyond the recommended timeHexcel warns that difficulty in processing may result, and advises evaluating resin wet-out and spreadability before use. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Electrical equipment near the fibre, and workers exposed to fine dust | Hexcel's HexForce SDS states that carbon fibre contained in some products is electrically conductive, and that fine dust clouds may form explosive mixtures with air. |
Handling and storage
- Store indoors in the original container, below 35°C and below 50% relative humidity, with shrink wrap left on until use.
- Avoid creating or accumulating dust. The Rave SDS advises avoiding dust and wearing safety goggles with side protection.
- Obtain, read and understand the safety data sheet for your sizing before use, as Hexcel's datasheet instructs.
Mitigations
- Use goggles with side protection when handling cut or abraded fibre, as the Rave SDS advises for carbon fibre threads.
Supply and geography
How common the raw materials are and where they come from.
PAN precursor (polyacrylonitrile) for HexTow IM7
Not applicable: a synthetic fibre made from a polymer precursor, so no crustal abundance applies
- Recycling
- Not stated in the sources read.
Hexcel HexTow IM7 manufacturing
Not stated
- Recycling
- Not stated in the sources read.
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.
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spore: profile
id: hextow-im7
spore_version: 0.2
family: carbon-materials
name: Hexcel HexTow IM7 carbon fibre
abbreviation: IM7
role: reinforcing fibre (intermediate-modulus carbon fibre)
category: carbon
type: carbon-fiber
summary: |
HexTow IM7 is Hexcel's intermediate-modulus, PAN-based carbon fibre, supplied as 12K continuous tows. Hexcel's IM7 datasheet prints a typical tensile strength of 5670 MPa and a tensile modulus of 276 GPa, with a density of 1.78 g/cm3 and an ultimate elongation of 1.8%. Hexcel states that IM7-G 12K (0.25%) has been qualified to NMS 818 Carbon Fiber Specification (NCAMP); we did not confirm that qualification in an NCAMP document. Laminate values for IM7 in HexPly 8552 resin belong to the prepreg profile (im7-8552) and are not recorded here.
best_for: Structural composites that need more stiffness and strength than a standard-modulus fibre such as AS4 (Hexcel selector guide)
weakest_at: Low strain at failure (1.8% per Hexcel), and no fibre-only compression, fatigue or space-exposure data in the sources read
identity:
formula: C (PAN-based carbon fibre, 95.0% carbon content per the Hexcel datasheet)
source: hexcel-im7-datasheet
where: Title block and Typical Fiber Properties table (Carbon Content row)
tags:
environments: []
stresses: []
applications:
- structures
properties:
- benchmark: ultimate_tensile_strength
label: Tensile strength, HexTow IM7 fibre (typical)
value: 5670
unit: MPa
scope: material
conditions:
form: continuous HexTow IM7 tow
basis: typical fibre property; Hexcel calls its performance values representative, not guaranteed
method: Manufacturer typical value printed on Hexcel's IM7 product data sheet
status: ground
note: The same row prints 820 ksi in U.S. units.
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Tensile Strength row, SI Units column
- benchmark: elastic_modulus
label: Tensile modulus, HexTow IM7 fibre (typical)
value: 276
unit: GPa
scope: material
conditions:
form: continuous HexTow IM7 tow
test_basis: printed as Tensile Modulus (Chord 6000-1000); the same row prints 40.0 Msi
method: Manufacturer typical value on Hexcel's datasheet; modulus is a chord between 6000 and 1000 as printed on the datasheet
status: ground
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Tensile Modulus row, SI Units column
- benchmark: elongation
label: Ultimate elongation at failure, HexTow IM7 fibre
value: 1.8
unit: '%'
scope: material
conditions:
form: continuous HexTow IM7 tow
basis: typical fibre property
method: Manufacturer typical value on Hexcel's datasheet
status: ground
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Ultimate Elongation at Failure row
- benchmark: density
label: Density, HexTow IM7 fibre
value: 1.78
unit: g/cm3
scope: material
conditions:
form: continuous HexTow IM7 tow
basis: typical fibre property
method: Manufacturer typical value on Hexcel's datasheet
status: ground
note: The same row prints 0.0643 lb/in3 in U.S. units. The selector guide prints 1.78 g/cm3 for IM7 too.
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Density row, SI Units column
- benchmark: carbon_content
label: Carbon content, HexTow IM7 fibre
value: 95
unit: '%'
scope: material
conditions:
form: continuous HexTow IM7 tow
basis: typical fibre property
method: Manufacturer typical value on Hexcel's datasheet
status: ground
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Carbon Content row
- benchmark: linear_density
label: Weight per length, 12K HexTow IM7 tow
value: 0.446
unit: g/m
scope: material
conditions:
form: 12K tow (12,000 filaments), as printed
basis: typical fibre property
method: Manufacturer typical value on Hexcel's datasheet
status: ground
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Weight/Length 12K row, SI Units column
- benchmark: filament_diameter
label: Filament diameter, HexTow IM7 fibre
value: 5.2
unit: microns
scope: material
conditions:
form: individual filament in the tow
basis: typical fibre property
method: Manufacturer typical value on Hexcel's datasheet
status: ground
note: The same row prints 0.203 mil in U.S. units.
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Filament Diameter row, SI Units column
- benchmark: thermal_conductivity
label: Thermal conductivity, HexTow IM7 yarn
value: 5.4
unit: W/m-ºK
scope: material
conditions:
form: yarn/tow
direction: not stated in the datasheet
method: Manufacturer value on Hexcel's datasheet
status: ground
note: The same row prints 3.12 Btu/hr-ft-ºF in U.S. units.
source: hexcel-im7-datasheet
where: Yarn/Tow Characteristics table, Thermal Conductivity row, SI Units column
- benchmark: cte
label: Coefficient of thermal expansion, HexTow IM7 yarn
value: -0.64
unit: ppm/ºC
scope: material
conditions:
form: yarn/tow
direction: not stated in the datasheet
method: Manufacturer value on Hexcel's datasheet
status: ground
note: The same row prints -0.36 ppm/ºF in U.S. units.
source: hexcel-im7-datasheet
where: Yarn/Tow Characteristics table, Coefficient of Thermal Expansion row, SI Units column
- benchmark: specific_heat
label: Specific heat, HexTow IM7 yarn
value: 0.21
unit: cal/g-°C
scope: material
conditions:
form: yarn/tow
method: Manufacturer value on Hexcel's datasheet
status: ground
note: The same row prints 0.21 Btu/lb-°F in U.S. units.
source: hexcel-im7-datasheet
where: Yarn/Tow Characteristics table, Specific Heat row, SI Units column
- benchmark: ultimate_tensile_strength
label: Comparison - tensile strength, HexTow IM8 fibre (typical)
value: 6170
unit: MPa
scope: material
conditions:
form: continuous HexTow IM8 tow
basis: typical fibre property; comparator, not IM7
method: Manufacturer typical value on Hexcel's IM8 product data sheet
status: ground
note: The same row prints 895 ksi in U.S. units.
source: hexcel-im8-datasheet
where: Typical Fiber Properties table, Tensile Strength row, SI Units column
- benchmark: elastic_modulus
label: Comparison - tensile modulus, HexTow IM8 fibre (typical)
value: 304
unit: GPa
scope: material
conditions:
form: continuous HexTow IM8 tow
test_basis: printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7
method: Manufacturer typical value on Hexcel's IM8 product data sheet
status: ground
source: hexcel-im8-datasheet
where: Typical Fiber Properties table, Tensile Modulus row, SI Units column
- benchmark: ultimate_tensile_strength
label: Comparison - tensile strength, HexTow IM6 fibre (typical, 12K)
value: 5860
unit: MPa
scope: material
conditions:
form: 12K HexTow IM6 tow
basis: typical fibre property; comparator, not IM7
method: Manufacturer typical value on Hexcel's IM6 product data sheet
status: ground
note: The same row prints 850 ksi in U.S. units.
source: hexcel-im6-datasheet
where: Typical Fiber Properties table, Tensile Strength (12K) row, SI Units column
- benchmark: elastic_modulus
label: Comparison - tensile modulus, HexTow IM6 fibre (typical)
value: 279
unit: GPa
scope: material
conditions:
form: continuous HexTow IM6 tow
test_basis: printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7
method: Manufacturer typical value on Hexcel's IM6 product data sheet
status: ground
source: hexcel-im6-datasheet
where: Typical Fiber Properties table, Tensile Modulus row, SI Units column
- benchmark: ultimate_tensile_strength
label: Comparison - tensile strength, HexTow AS7 fibre (typical)
value: 4930
unit: MPa
scope: material
conditions:
form: continuous HexTow AS7 tow
basis: typical fibre property; comparator, not IM7
method: Manufacturer typical value on Hexcel's AS7 product data sheet
status: ground
note: The same row prints 715 ksi in U.S. units.
source: hexcel-as7-datasheet
where: Typical Fiber Properties table, Tensile Strength row, SI Units column
- benchmark: elastic_modulus
label: Comparison - tensile modulus, HexTow AS7 fibre (typical)
value: 243
unit: GPa
scope: material
conditions:
form: continuous HexTow AS7 tow
test_basis: printed as Tensile Modulus (Chord 6000-1000); comparator, not IM7
method: Manufacturer typical value on Hexcel's AS7 product data sheet
status: ground
source: hexcel-as7-datasheet
where: Typical Fiber Properties table, Tensile Modulus row, SI Units column
- benchmark: ultimate_tensile_strength
label: Comparison - tensile strength, HexTow AS4 fibre (typical)
value: 4501
unit: MPa
scope: material
conditions:
form: continuous HexTow AS4 tow
basis: tow tensile strength from the aerospace-grade table; comparator, not IM7
method: Manufacturer typical value in Hexcel's selector guide
status: ground
note: The same row prints 650 ksi.
source: hexcel-selector-guide
where: Aerospace-Grade HexTow Carbon Fiber table, AS4 row, Tensile Strength (MPa) column (page 2)
- benchmark: elastic_modulus
label: Comparison - tensile modulus, HexTow AS4 fibre (typical)
value: 231
unit: GPa
scope: material
conditions:
form: continuous HexTow AS4 tow
basis: tow tensile modulus from the aerospace-grade table; comparator, not IM7
method: Manufacturer typical value in Hexcel's selector guide
status: ground
note: The same row prints 33.5 Msi.
source: hexcel-selector-guide
where: Aerospace-Grade HexTow Carbon Fiber table, AS4 row, Tensile Modulus (GPa) column (page 2)
corrosion:
- environment: Storage of carbon fibre in warm or humid conditions (ageing rather than corrosion)
headline: Hexcel gives one year of constant properties for unsized fibre and five years for GP or GS sized fibre, if stored indoors below 35°C and below 50% relative humidity.
effect: Hexcel's storage guidance, which covers HexTow carbon fibre in general and does not list IM7 separately, says unsized fibre keeps its tow tensile strength, tow tensile modulus, tow tensile elongation and fibre density for at least one year from manufacture, and GP and GS sized fibre keeps them for at least five years. Fibre stored at high temperature or high humidity, or beyond the recommended time, may process badly, and Hexcel advises checking its processing (resin wet-out and spreadability) before use.
rating: low
conditions:
storage: indoors, in original containers, below 35°C (95°F) and below 50% RH; shrink wrap kept on until use
exposure: high temperature or high humidity, or storage beyond the recommended time
source: hexcel-selector-guide
where: Recommended Storage and Shelf Life panel, page 6
risks:
hazards:
- text: Hexcel's SDS for HexForce woven carbon fabric (revision 1.1, dated 8/10/2020) states the product is not hazardous under the OSHA Hazard Communication Standard, and rates its physical, health and environmental hazards as not classified. It is a woven-fabric SDS, not an IM7 tow SDS.
ghs: []
source: hexforce-sds
where: Section 2, Classification of the substance or mixture
- text: The same HexForce SDS warns of mild, temporary mechanical eye and skin irritation, and says fine dust clouds may form explosive mixtures with air.
ghs: []
source: hexforce-sds
where: Section 2, Other hazards (hazards not otherwise classified)
- text: Rave Scientific's SDS for high-purity carbon fibres in carbon fibre threads (version 4.0, dated October 5th 2022) says the substance does not meet the classification criteria of Regulation EC Nr. 1272/2008. It gives an EU occupational exposure limit of 10 mg/m3 TWA for carbon (C) fibres. That product is a carbon-coating thread, not IM7 tow.
ghs: []
source: rave-sds
where: Section 2.1 and Section 8.1 (occupational exposure limits)
failure_risks:
- mode: Brittle fracture at low strain
trigger: Tensile loading of the fibre to failure
consequence: Hexcel lists an ultimate elongation at failure of 1.8% for IM7, so the fibre breaks after only a small stretch.
severity: moderate
source: hexcel-im7-datasheet
where: Typical Fiber Properties table, Ultimate Elongation at Failure row
- mode: Loss of processing quality after poor storage
trigger: Storage above 35°C or above 50% relative humidity, or storage beyond the recommended time
consequence: Hexcel warns that difficulty in processing may result, and advises evaluating resin wet-out and spreadability before use.
severity: low
source: hexcel-selector-guide
where: Recommended Storage and Shelf Life panel, page 6
side_effects:
- text: Hexcel's HexForce SDS states that carbon fibre contained in some products is electrically conductive, and that fine dust clouds may form explosive mixtures with air.
affects: Electrical equipment near the fibre, and workers exposed to fine dust
source: hexforce-sds
where: Section 2, Physicochemical hazards and Other hazards
handling:
- text: Store indoors in the original container, below 35°C and below 50% relative humidity, with shrink wrap left on until use.
source: hexcel-selector-guide
where: Recommended Storage and Shelf Life panel, page 6
- text: Avoid creating or accumulating dust. The Rave SDS advises avoiding dust and wearing safety goggles with side protection.
source: rave-sds
where: Sections 8.2 and 10.4
- text: Obtain, read and understand the safety data sheet for your sizing before use, as Hexcel's datasheet instructs.
source: hexcel-im7-datasheet
where: Safety Information
mitigations:
- text: Use goggles with side protection when handling cut or abraded fibre, as the Rave SDS advises for carbon fibre threads.
source: rave-sds
where: Section 8.2 (personal protection)
uses:
- application: structures
device: Aerospace structures using an aerospace-grade fibre
example: Hexcel's IM7 datasheet states that IM7-G 12K (0.25%) carbon fiber has been qualified to NMS 818 Carbon Fiber Specification (NCAMP), so customers can call out an industry standard, aerospace grade carbon fiber without writing their own specification.
source: hexcel-im7-datasheet
where: Page 1, second paragraph
- application: structures
device: Formula 1 cars, competition racing boats and high-performance cars
example: Hexcel's selector guide says HexTow standard and intermediate modulus carbon fiber is selected for winning Formula 1 cars, competition racing boats, high-performance cars, and composite tooling material.
source: hexcel-selector-guide
where: Industrial-Grade HexTow Carbon Fiber panel, page 4
supply:
- subject: PAN precursor (polyacrylonitrile) for HexTow IM7
abundance: 'Not applicable: a synthetic fibre made from a polymer precursor, so no crustal abundance applies'
producers: []
critical_lists: []
recycling: Not stated in the sources read.
substitutes: []
source: wikipedia-carbon-fiber
where: Precursor paragraph of the article, which names 'polyacrylonitrile (PAN), rayon, or petroleum pitch' as precursors
- subject: Hexcel HexTow IM7 manufacturing
abundance: Not stated
producers: []
critical_lists: []
recycling: Not stated in the sources read.
substitutes: []
source: hexcel-im7-datasheet
where: Title block names Hexcel Corporation; the datasheet does not give a plant location or production share
documents:
- title: HexTow IM7 Carbon Fiber Product Data Sheet (Hexcel, 2023)
type: datasheet
url: https://www.hexcel.com/wp-content/uploads/2025/12/IM7_HexTow_DataSheet.pdf
year: 2023
- title: HexTow Carbon Fiber selector guide and composite properties (Hexcel, CTU 396 FB25)
type: datasheet
url: https://www.hexcel.com/wp-content/uploads/2026/01/HexTowSelectorGuide.pdf
year: 2025
- title: HexTow IM8 Carbon Fiber Product Data Sheet (Hexcel)
type: datasheet
url: https://hexcel.com/wp-content/uploads/2026/01/IM8_HexTow_DataSheet.pdf
year: 2023
- title: HexTow AS7 Carbon Fiber Product Data Sheet (Hexcel)
type: datasheet
url: https://hexcel.com/wp-content/uploads/2025/12/AS7_Aerospace_HexTow_DataSheet.pdf
year: 2025
- title: HexTow IM6 Carbon Fiber Product Data Sheet (Hexcel)
type: datasheet
url: https://hexcel.com/wp-content/uploads/2025/12/IM6_HexTow_DataSheet.pdf
year: 2025
- title: 'Safety Data Sheet: High purity carbon fibers in carbon fiber threads (Rave Scientific, SDS00170CC1016 v4.0)'
type: sds
url: https://ravescientific.com/images/pdf/SDS00170CC1016-01_Carbon_Fibre.pdf
year: 2022
- title: 'Safety Data Sheet: HexForce Carbon Fabric (Hexcel, revision 1.1, as hosted by Revchem Composites)'
type: sds
url: https://www.revchem.com/?p=30574
year: 2020
gaps:
- No flight, vacuum, radiation or low-Earth-orbit data for the IM7 fibre were found in the sources read.
- Electrical resistivity (printed as 1.5 x 10-3 ohm-cm in the IM7 datasheet) and the 6K weight, approximate yield and cross-sectional area rows are printed in exponent form or units that the checker cannot match, so they are left out.
- The HexPly 8552 laminate values in the IM7 datasheet and selector guide (0-degree tensile, flexural, compression and 90-degree tensile at 60% fibre volume) describe the prepreg system, not the fibre. They are not recorded here; see the im7-8552 profile.
- Hexcel's IM7 datasheet states that IM7-G 12K (0.25%) is qualified to NMS 818 (NCAMP). We did not confirm this in an NCAMP document. A search result (not opened) described a prepreg specification in which IM7 qualification to NMS 818 was still in progress; treat the qualification as unconfirmed until checked.
- The Hexcel datasheets do not name the manufacturing plant, so no producer country or production share is recorded. USGS Mineral Commodity Summaries do not cover PAN-based carbon fibre.
- No oxidation or thermal-ageing figure for the IM7 fibre in air was found. Wikipedia gives no numbers for carbon fibre oxidation.
- No fibre-only compression, interlaminar, fatigue or outgassing value for IM7 was found in the sources read.
- Thermal conductivity and coefficient of thermal expansion are printed without a stated direction (axial or transverse).
- No hazard data for the IM7 tow itself were found. The two SDSs read are for woven carbon fabric and a high-purity carbon thread, not for IM7 tow.
- PubChem hazard data for acrylonitrile, the monomer for PAN, could not be opened (automated access blocked), so precursor hazards are not recorded.
- Property names carbon_content, linear_density and filament_diameter are not in spores/property-canon.yaml and are kept as printed.
- 'Designations: only the trade name HexTow IM7 is recorded; no UNS, EN or AISI-style codes apply to a carbon fibre.'
sources:
hexcel-im7-datasheet:
title: HexTow IM7 Carbon Fiber Product Data Sheet (Hexcel Corporation, copyright 2023, CTA 351 AG23)
id: Hexcel CTA 351 AG23; the same file is also served at wp-content/uploads/2026/01/IM7_HexTow_DataSheet.pdf
url: https://www.hexcel.com/wp-content/uploads/2025/12/IM7_HexTow_DataSheet.pdf
year: 2023
kind: datasheet
license: Hexcel data sheet, cited not reproduced
hexcel-selector-guide:
title: 'HexTow Carbon Fiber: aerospace-grade and industrial-grade selector guide with composite properties (Hexcel, CTU 396 FB25)'
id: Hexcel CTU 396 FB25, copyright 2025
url: https://www.hexcel.com/wp-content/uploads/2026/01/HexTowSelectorGuide.pdf
year: 2025
kind: datasheet
license: Hexcel brochure, cited not reproduced
hexcel-im8-datasheet:
title: HexTow IM8 Carbon Fiber Product Data Sheet (Hexcel Corporation)
id: Hexcel CTA IM8 product data sheet, copyright 2023
url: https://hexcel.com/wp-content/uploads/2026/01/IM8_HexTow_DataSheet.pdf
year: 2023
kind: datasheet
license: Hexcel data sheet, cited not reproduced
hexcel-as7-datasheet:
title: HexTow AS7 Carbon Fiber Product Data Sheet (Hexcel Corporation)
id: Hexcel AS7 product data sheet (upload path 2025/12)
url: https://hexcel.com/wp-content/uploads/2025/12/AS7_Aerospace_HexTow_DataSheet.pdf
year: 2025
kind: datasheet
license: Hexcel data sheet, cited not reproduced
hexcel-im6-datasheet:
title: HexTow IM6 Carbon Fiber Product Data Sheet (Hexcel Corporation)
id: Hexcel IM6 product data sheet (upload path 2025/12)
url: https://hexcel.com/wp-content/uploads/2025/12/IM6_HexTow_DataSheet.pdf
year: 2025
kind: datasheet
license: Hexcel data sheet, cited not reproduced
wikipedia-carbon-fiber:
title: 'Carbon fiber (Wikipedia article): composition, precursors and history only'
id: en.wikipedia.org Carbon_fiber
url: https://en.wikipedia.org/wiki/Carbon_fiber
year: 2026
kind: web
license: CC BY-SA 4.0 (Wikipedia text, cited for precursor names only)
rave-sds:
title: 'Safety Data Sheet: High purity carbon fibers in carbon fiber threads (Rave Scientific, SDS00170CC1016 v4.0, 5 October 2022)'
id: 'Rave Scientific SDS00170CC1016, version 4.0; EC # 231-955-3'
url: https://ravescientific.com/images/pdf/SDS00170CC1016-01_Carbon_Fibre.pdf
year: 2022
kind: datasheet
license: Supplier SDS, linked not reproduced
hexforce-sds:
title: 'Safety Data Sheet: HexForce Carbon Fabric, product 20584US-2 (Hexcel Corporation, revision 1.1, 8/10/2020), as hosted by Revchem Composites'
id: Hexcel SDS, revision 1.1 supersedes 5/1/2015
url: https://www.revchem.com/?p=30574
year: 2020
kind: datasheet
license: Supplier SDS, linked not reproduced
license: CC-BY-4.0
updated: '2026-11-02'
review:
status: draft
method: assistant
checked_values: 18
unreachable: 2
caveats: 3
note: Read by an AI assistant on 2026-11-02 from the Hexcel datasheets (IM7, IM8, AS7, IM6), the Hexcel selector guide, the Wikipedia article, and two SDSs. Hexcel's NMS 818 qualification claim is not confirmed in an NCAMP document. PubChem and the NCAMP base specification could not be opened.
story:
recipe:
line: HexTow IM7 is a continuous, PAN-based carbon fibre. A polyacrylonitrile (PAN) precursor is heated to drive off non-carbon atoms, which leaves carbon fibre, and Hexcel then surface treats and sizes the yarn (Wikipedia; Hexcel datasheet).
parts:
- name: Carbon
symbol: C
role: The fibre itself. Hexcel prints a carbon content of 95.0% for IM7; the sizing and other elements make up the balance, and the datasheet does not itemise them.
risk_groups:
- title: For people
level: 0
verdict: Not classified as hazardous in the SDSs we checked
lead: The Hexcel fabric SDS and the Rave thread SDS classify carbon fibre as not hazardous. Both describe dust, and the Hexcel SDS notes mild irritation.
points:
- label: Dust
line: Fine dust clouds may form explosive mixtures with air, per the Hexcel fabric SDS. The Rave SDS advises avoiding dust.
- label: Skin and eyes
line: Hexcel's SDS notes mild, temporary mechanical irritation of the eyes and skin.
- label: Exposure limit
line: The Rave SDS gives an EU occupational exposure limit of 10 mg/m3 TWA for carbon (C) fibres.
- title: If a part fails
lead: Breakage at low strain is the main mechanical risk. The sources do not give a failure test for finished parts.
points:
- label: Strain at failure
line: Hexcel gives IM7 an ultimate elongation at failure of 1.8%, so the fibre can break after only a small stretch.
- title: Storage and handling
verdict: Keep it indoors and in its original container
points:
- label: Storage
line: Hexcel says to store it indoors, below 35°C and below 50% relative humidity.
- label: Age
line: Hexcel gives one year for unsized fibre and five years for GP or GS sized fibre.
why: Carbon fibre is a fine carbon filament used as reinforcement in composite parts. HexTow IM7 is Hexcel's intermediate-modulus carbon fibre, made from PAN and supplied as 12K tows. Hexcel's datasheet prints a typical tensile strength of 5670 MPa and a tensile modulus of 276 GPa for the fibre. Hexcel sells IM7 for weaving, prepregging, filament winding, braiding and pultrusion, so it is an input to composite parts rather than a finished part.
uses:
- where: Aerospace structures
line: Hexcel says IM7-G 12K (0.25%) carbon fiber has been qualified to NMS 818 Carbon Fiber Specification (NCAMP). That lets a buyer call out an industry standard, aerospace grade fibre without writing its own specification. We did not confirm that qualification in an NCAMP document.
- where: Racing cars and boats
line: Hexcel's selector guide says its standard and intermediate modulus fibres are selected for Formula 1 cars, competition racing boats and high-performance cars.
can_do:
- label: Strength
line: Carry a typical tensile strength of 5670 MPa at a density of 1.78 g/cm3, per Hexcel's IM7 datasheet.
- label: Give a stiffer fibre than AS4
line: a tensile modulus of 276 GPa against 231 GPa for AS4, per Hexcel's selector guide.
- label: Strength
line: Be woven, prepregged, filament wound, braided or pultruded, as Hexcel recommends for the fibre.
compare: Against Hexcel's standard-modulus AS4 fibre, IM7 has a typical tensile strength of 5670 MPa against 4501 MPa, and a tensile modulus of 276 GPa against 231 GPa (Hexcel selector guide). Against the newer IM8, the IM8 datasheet prints 6170 MPa and 304 GPa, so IM8 is stronger and stiffer. The IM6 datasheet prints 5860 MPa and 279 GPa, and the AS7 datasheet, which describes AS7 as high strain, prints 4930 MPa and 243 GPa. Hexcel calls its performance values representative, not guaranteed, and the figures come from separate datasheets rather than one test series.
compare_rows:
- label: Tensile strength
benchmark: ultimate_tensile_strength
- label: Tensile modulus
benchmark: elastic_modulus
- label: Density
benchmark: density
handling:
- Store indoors in the original container, below 35°C and below 50% relative humidity.
- Avoid creating dust. Wear goggles with side protection when handling cut or abraded fibre.
- Read the supplier's safety data sheet for your sizing before use.
good_for:
- 'Structures that need more stiffness and strength than a standard-modulus fibre: IM7 gives 276 GPa against 231 GPa for AS4.'
- 'Aerospace programmes that specify a qualified fibre: Hexcel says IM7-G 12K (0.25%) is qualified to NMS 818, pending independent confirmation.'
watch_out:
- 'Low strain at failure: IM7 breaks at 1.8% elongation according to Hexcel.'
- 'Ageing: Hexcel''s storage guidance gives one year for unsized fibre and five years for GP or GS sized fibre; beyond that the fibre may process badly.'
- 'Typical values, not guarantees: Hexcel calls its performance figures representative.'
verdict: In Hexcel's range, IM7 is the stiffer and stronger choice over AS4, and Hexcel says it is qualified to NMS 818 for aerospace work. Confirm that qualification with NCAMP before you rely on it.
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 |
|---|---|---|---|---|
| HexTow IM7 Carbon Fiber Product Data Sheet (Hexcel Corporation, copyright 2023, CTA 351 AG23) | datasheet | 2023 | 15 values | |
| HexTow Carbon Fiber: aerospace-grade and industrial-grade selector guide with composite properties (Hexcel, CTU 396 FB25) | datasheet | 2025 | 6 values | |
| HexTow IM8 Carbon Fiber Product Data Sheet (Hexcel Corporation) | datasheet | 2023 | 2 values | |
| HexTow AS7 Carbon Fiber Product Data Sheet (Hexcel Corporation) | datasheet | 2025 | 2 values | |
| HexTow IM6 Carbon Fiber Product Data Sheet (Hexcel Corporation) | datasheet | 2025 | 2 values | |
| Carbon fiber (Wikipedia article): composition, precursors and history only | web | 2026 | 1 value | |
| Safety Data Sheet: High purity carbon fibers in carbon fiber threads (Rave Scientific, SDS00170CC1016 v4.0, 5 October 2022) | datasheet | 2022 | 3 values | |
| Safety Data Sheet: HexForce Carbon Fabric, product 20584US-2 (Hexcel Corporation, revision 1.1, 8/10/2020), as hosted by Revchem Composites | datasheet | 2020 | 3 values |
Updated