Carbon nanotubes CNT
C (single-wall or multi-wall tubes of sp2-bonded carbon · hexagonal lattice rolled into a tube
Carbon nanotubes are graphene sheets rolled into tubes.
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.
Strength of CNT yarn
20 to 80 GPa
Electrical conduction
1×10^5 S/m
Recipe, share of the weight
- C 100.0%Carbon
Best for
Ideal single-tube stiffness and strength on paper; macroscopic CNT yarns for electrically conductive, lightweight fibre (the review reports conductivity above 10^5 S/m for yarns)
Weakest at
Real macroscopic yarns are far weaker than ideal tubes (0.8 GPa twisted yarn against 150 GPa ideal), and handling of loose CNT material is a health concern (HSE)
Risk at a glance
- People Low. Handle as a precaution
- If it fails No data. No failure risks recorded
- Corrosion Moderate. n-type SWCNT films degrade in air, and argon storage keeps them stable
Quick facts: CNT
| Property | Value | Basis |
|---|---|---|
| Tensile strength | 50 to 80,000 MPa | 6 sourced values across conditions |
| Young's modulus | 14 to 68 GPa | 2 sourced values across conditions |
| Thermal conductivity | 1,750 to 5,800 W/(m·K) | 2 sourced values across conditions |
What is the thermal conductivity of Carbon nanotubes (CNT)?
Carbon nanotubes (CNT) has a thermal conductivity of 1,750 to 5,800 W/(m·K). 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 tensile strength of Carbon nanotubes (CNT)?
Carbon nanotubes (CNT) has a tensile strength of 50 to 80,000 MPa. The range covers 6 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 Carbon nanotubes (CNT)?
Carbon nanotubes (CNT) has a Young's modulus of 14 to 68 GPa. 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 Carbon nanotubes (CNT) used for?
Uses recorded in the sources include Fully printed all-carbon thermoelectric generator on flexible Kapton; Self-powered CNT composite strain sensor.
Why it exists
Carbon nanotubes combine very high ideal strength and stiffness with electrical conduction. The values for ideal single tubes are theoretical. Macroscopic CNT yarns read here reach 0.8 GPa tensile strength and conduct at up to 8.5e6 S/m for the best reported assembly.
Recipe
C (single-wall or multi-wall tubes of sp2-bonded carbon; yarns and sheets are assemblies of such tubes)
Carbon nanotubes are graphene sheets rolled into tubes, with every atom bonded to three neighbours in a hexagonal lattice. Single-wall tubes have one wall and multi-wall tubes have several coaxial walls. The review reads from a supplier growth furnace with iron catalyst nanoparticles, and cites a CVD-based direct spinning route for yarns. Arc discharge and HiPco were not read from a fetched source.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Carbon C | 1 | 100.0% | The only element in a pure CNT. The tube wall is a rolled sheet of sp2-bonded carbon, so the material is pure carbon unless metal catalyst or contamination remains. |
Weight shares are calculated from standard atomic weights.
What it can do
Strength of CNT yarn
20 to 80 GPa
measured
Twisted CNT yarn reaches 0.8 GPa tensile strength and 14 GPa modulus, with 14 percent elongation to failure, in the review's Table 1. The ideal single-tube figure of 150 GPa is a theoretical limit, not a yarn value.
Electrical conduction
1×10^5 S/m
measured
As-received CNT yarn conducts at 100000 S/m, and twisted yarn at 500000 S/m. The best reported macroscopic CNT assembly reaches 8.5e6 S/m.
How it compares
Ideal single tubes are the strongest and stiffest values in this profile, but the macroscopic yarns read here are much weaker. Thermal conductivity of CNTs was not read in this run, so the profile does not compare heat conduction with graphene or metals.
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 | CNT |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity, individual CNT at room temperature (measured range) | 3000 to 3500 W/mK9 |
| Thermal conductivity, single-walled CNT rope at room temperature | 1750 to 5800 W/mK10 |
| Thermal conductivity, individual CNT (simulation prediction) | 6600 W m-1 K-111 |
| Physical and electrical | |
| Electrical conductivity, as-received CNT yarn | 1×10^5 S/m5 |
| Electrical conductivity, twisted CNT yarn | 5×10^5 S/m6 |
| Electrical conductivity, best reported macroscopic CNT assemblyValue stated in the Introduction of the review | 8.5×10^6 S/m |
| Other measurements | |
| Tensile strength, ideal single tube (theory) | 150 GPa1 |
| Young's modulus, ideal MWCNT (theory)Range stated in the Introduction of the review | 0.9 to 1.2 TPa |
| Tensile strength, MWCNTs and bundlesRange stated in the Introduction of the review | 20 to 80 GPa |
| Elongation to failure, MWCNTsRange stated in the Introduction of the review | 5 to 15 % |
| Tensile strength, meter-long CNT assembliesRange stated in the Introduction of the review | 3 to 5.5 GPa |
| Tensile strength, short CNT assembly samples (best)Value stated in the Introduction of the review | 9.6 GPa |
| Tensile strength, solution-spun CNT filamentsRange stated in the Introduction of the review | 50 to 150 MPa |
| Tensile strength, twisted CNT yarn | 0.8 GPa2 |
| Young's modulus, twisted CNT yarn | 14 GPa3 |
| Elongation to failure, twisted CNT yarn | 14 %4 |
| Tensile strength, cured DCPD-CNT composite yarn | 1.2 GPa7 |
| Young's modulus, cured DCPD-CNT composite yarn | 68 GPa8 |
Why choose it, and why not
Good for
- Lightweight conductive yarns and assemblies, where the macroscopic conductivity and modulus values matter more than the ideal single-tube limit.
Watch out for
- Ideal single-tube values are theoretical and are far above the yarn values measured in the review.
- Thermal conductivity, ageing and space-use data are not in this profile.
- Inhalation risk from loose CNT material is not settled, and HSE says long-term effects of repeated exposure are not known.
Carbon nanotubes have very high ideal strength and stiffness on paper. The yarns read here are much weaker and conduct electricity well. This profile is a partial draft until the thermal, synthesis, health and space sources are read.
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, ideal single tube (theory) | Value stated in the Introduction of an open-access CNT review, citing theoretical work | basis ideal defect-free single tube, quoted from theory in the review; chirality and test conditions not stated | — |
| 2 | Tensile strength, twisted CNT yarn | Value stated in the abstract and Section 3.2 of the review, Table 1 | basis pristine twisted CNT yarn, as printed in Table 1; test method not stated in the abstract | — |
| 3 | Young's modulus, twisted CNT yarn | Value stated in the abstract and Table 1 of the review | basis twisted CNT yarn, as printed in Table 1 | — |
| 4 | Elongation to failure, twisted CNT yarn | Value stated in the abstract and Table 1 of the review | basis twisted CNT yarn, as printed in Table 1 | — |
| 5 | Electrical conductivity, as-received CNT yarn | Value stated in the abstract and Section 3.2 of the review | basis as-received CNT yarn, as printed in Section 3.2 and Figure 8 | — |
| 6 | Electrical conductivity, twisted CNT yarn | Value stated in the abstract and Section 3.2 of the review | basis twisted CNT yarn, as printed in Section 3.2 and Figure 8 | — |
| 7 | Tensile strength, cured DCPD-CNT composite yarn | Value stated in the abstract and Table 1 of the review | basis cured DCPD resin infused into CNT yarn, as printed in Table 1; resin is not pure CNT | — |
| 8 | Young's modulus, cured DCPD-CNT composite yarn | Value stated in the abstract and Table 1 of the review | basis cured DCPD resin infused into CNT yarn, as printed in Table 1; resin is not pure CNT | — |
| 9 | Thermal conductivity, individual CNT at room temperature (measured range) | Range stated in the Introduction of an arXiv review of 1D carbon nanomaterials, citing prior measurements | basis carbon nanotube at room temperature, as printed in the review; tube type and length not stated in the sentence | — |
| 10 | Thermal conductivity, single-walled CNT rope at room temperature | Range stated in the section on CNT fibres of the arXiv review, citing one measurement | basis single-walled CNT rope, room temperature, as printed in the review | — |
| 11 | Thermal conductivity, individual CNT (simulation prediction) | Predicted value cited from molecular dynamics simulation (Berber, Kwon and Tomanek, 2000) in a 2013 Reviews of Modern Physics review | basis individual CNT at room temperature, predicted by simulation; not a measured value | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at room temperature, n-type SWCNT films (atmospheric stability) | moderate | n-type SWCNT films degrade in air, and argon storage keeps them stable1 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at room temperature, n-type SWCNT films (atmospheric stability) | The review reports degradation after 9 months of storage in air, and no degradation after 9 months in argon, citing the underlying work. Re-exposure to air converts one n-type film back to p-type. | atmosphere air versus argon storageduration 9 months |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
No nanomaterial exposure limit is set in the UK, and HSE advises a precautionary approach for CNTs that can be inhaled.
- Inhalation
- Long straight CNT fibres should be assumed to carry the health risks HSE identifies for biopersistent fibres. Tangled bundles may still cause lung inflammation.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Dust explosions are possible when carbon powder is mixed with air,… | Dust explosions are possible when carbon powder is mixed with air, according to the ICSC note for carbon. This is for carbon powder in general, not CNT tested specifically. |
Handling and storage
- HSE advises a precautionary risk management approach when workers may inhale CNTs or other biopersistent high aspect ratio nanomaterials.
Supply and geography
How common the raw materials are and where they come from.
Natural graphite (carbon feedstock, as used for graphite and graphene)
World mine production of natural graphite is 1,800,000 tons (2025 estimate) from 1,550,000 tons (2024). World reserves are 310,000,000 tons, of which China holds 100,000,000 tons. Rest-of-world resources are said to exceed 800 million tons of recoverable graphite.
- Top producers (2025)
- China 82%
Natural graphite imports to the United States
US natural graphite imports in 2025 were an estimated 79,000 tons (73.4 percent flake and high-purity).
- Top producers (2024)
- China (2021 to 2024 import share) 46%, Canada 13%, Mozambique 13%
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: carbon-nanotubes
spore_version: 0.2
family: carbon-materials
name: Carbon nanotubes
abbreviation: CNT
role: Rolled sheets of carbon (single-wall, multi-wall) and macroscopic CNT yarns and sheets
category: carbon
type: Nanotubes
summary: |
Carbon nanotubes are graphene sheets rolled into tubes. Single-wall tubes (SWCNT) have one wall and multi-wall tubes (MWCNT) have several coaxial walls. Ideal single-tube strength and stiffness values quoted in a 2020 open-access review are far above what macroscopic CNT yarns achieve. In the same review, a twisted CNT yarn reaches 0.8 GPa tensile strength and 14 GPa modulus, and the best reported macroscopic CNT assembly conducts at up to 8.5e6 S/m. Thermal conductivity of CNT materials was not read in this run and is not given.
best_for: Ideal single-tube stiffness and strength on paper; macroscopic CNT yarns for electrically conductive, lightweight fibre (the review reports conductivity above 10^5 S/m for yarns)
weakest_at: Real macroscopic yarns are far weaker than ideal tubes (0.8 GPa twisted yarn against 150 GPa ideal), and handling of loose CNT material is a health concern (HSE)
identity:
formula: C (single-wall or multi-wall tubes of sp2-bonded carbon; yarns and sheets are assemblies of such tubes)
cas: ''
crystal_system: hexagonal lattice rolled into a tube (chirality sets the wrap)
space_group: ''
source: pmc7221842
where: Section 1 (Introduction), description of MWCNT and SWCNT structure and values; the wall-count and chirality definitions are not stated numerically in the sections read
tags:
environments: []
stresses: []
applications:
- structures
- electronics-and-chips
properties:
- benchmark: ultimate_tensile_strength
label: Tensile strength, ideal single tube (theory)
value: 150
unit: GPa
scope: material
conditions:
basis: ideal defect-free single tube, quoted from theory in the review; chirality and test conditions not stated
method: Value stated in the Introduction of an open-access CNT review, citing theoretical work
status: calculated
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: elastic_modulus
label: Young's modulus, ideal MWCNT (theory)
value: 0.9
value_high: 1.2
bound: range
unit: TPa
scope: material
conditions:
basis: ideal multi-wall tube; range as printed in the review
method: Range stated in the Introduction of the review
status: calculated
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, MWCNTs and bundles
value: 20
value_high: 80
bound: range
unit: GPa
scope: material
conditions:
basis: multi-wall tubes and bundles, as printed; test method not stated
method: Range stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: elongation
label: Elongation to failure, MWCNTs
value: 5
value_high: 15
bound: range
unit: '%'
scope: material
conditions:
basis: multi-wall tubes, as printed; test method not stated
method: Range stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, meter-long CNT assemblies
value: 3
value_high: 5.5
bound: range
unit: GPa
scope: material
conditions:
basis: macroscopic meter-long assemblies, as printed
method: Range stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, short CNT assembly samples (best)
value: 9.6
unit: GPa
scope: material
conditions:
basis: short assembly samples, upper value as printed
method: Value stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, solution-spun CNT filaments
value: 50
value_high: 150
bound: range
unit: MPa
scope: material
conditions:
basis: macroscopic solution-spun filaments, as printed
method: Range stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, twisted CNT yarn
value: 0.8
unit: GPa
scope: material
conditions:
basis: pristine twisted CNT yarn, as printed in Table 1; test method not stated in the abstract
method: Value stated in the abstract and Section 3.2 of the review, Table 1
status: ground
source: pmc7221842
where: Abstract; Section 3.2; Table 1
- benchmark: elastic_modulus
label: Young's modulus, twisted CNT yarn
value: 14
unit: GPa
scope: material
conditions:
basis: twisted CNT yarn, as printed in Table 1
method: Value stated in the abstract and Table 1 of the review
status: ground
source: pmc7221842
where: Abstract; Table 1
- benchmark: elongation
label: Elongation to failure, twisted CNT yarn
value: 14
unit: '%'
scope: material
conditions:
basis: twisted CNT yarn, as printed in Table 1
method: Value stated in the abstract and Table 1 of the review
status: ground
source: pmc7221842
where: Abstract; Table 1
- benchmark: electrical_conductivity
label: Electrical conductivity, as-received CNT yarn
value: 100000
unit: S/m
scope: material
conditions:
basis: as-received CNT yarn, as printed in Section 3.2 and Figure 8
method: Value stated in the abstract and Section 3.2 of the review
status: ground
source: pmc7221842
where: Abstract; Section 3.2; Figure 8
- benchmark: electrical_conductivity
label: Electrical conductivity, twisted CNT yarn
value: 500000
unit: S/m
scope: material
conditions:
basis: twisted CNT yarn, as printed in Section 3.2 and Figure 8
method: Value stated in the abstract and Section 3.2 of the review
status: ground
source: pmc7221842
where: Abstract; Section 3.2; Figure 8
- benchmark: electrical_conductivity
label: Electrical conductivity, best reported macroscopic CNT assembly
value: 8500000
unit: S/m
scope: material
conditions:
basis: best reported CNT assembly, as printed in Section 1
method: Value stated in the Introduction of the review
status: ground
source: pmc7221842
where: Section 1 (Introduction)
- benchmark: ultimate_tensile_strength
label: Tensile strength, cured DCPD-CNT composite yarn
value: 1.2
unit: GPa
scope: material
conditions:
basis: cured DCPD resin infused into CNT yarn, as printed in Table 1; resin is not pure CNT
method: Value stated in the abstract and Table 1 of the review
status: ground
source: pmc7221842
where: Abstract; Table 1
- benchmark: elastic_modulus
label: Young's modulus, cured DCPD-CNT composite yarn
value: 68
unit: GPa
scope: material
conditions:
basis: cured DCPD resin infused into CNT yarn, as printed in Table 1; resin is not pure CNT
method: Value stated in the abstract and Table 1 of the review
status: ground
source: pmc7221842
where: Abstract; Table 1
- benchmark: thermal_conductivity
label: Thermal conductivity, individual CNT at room temperature (measured range)
value: 3000
value_high: 3500
bound: range
unit: W/mK
scope: material
conditions:
basis: carbon nanotube at room temperature, as printed in the review; tube type and length not stated in the sentence
method: Range stated in the Introduction of an arXiv review of 1D carbon nanomaterials, citing prior measurements
status: ground
source: arxiv-zhan-gu
where: Introduction, first paragraph on CNT thermal conductivity
- benchmark: thermal_conductivity
label: Thermal conductivity, single-walled CNT rope at room temperature
value: 1750
value_high: 5800
bound: range
unit: W/mK
scope: material
conditions:
basis: single-walled CNT rope, room temperature, as printed in the review
method: Range stated in the section on CNT fibres of the arXiv review, citing one measurement
status: ground
source: arxiv-zhan-gu
where: Section on CNT fibres (text cites reference 151)
- benchmark: thermal_conductivity
label: Thermal conductivity, individual CNT (simulation prediction)
value: 6600
unit: W m-1 K-1
scope: material
conditions:
basis: individual CNT at room temperature, predicted by simulation; not a measured value
method: Predicted value cited from molecular dynamics simulation (Berber, Kwon and Tomanek, 2000) in a 2013 Reviews of Modern Physics review
status: calculated
source: marconnet-rmp
where: Section on individual CNT thermal conduction, first paragraph
corrosion:
- environment: Air at room temperature, n-type SWCNT films (atmospheric stability)
headline: n-type SWCNT films degrade in air, and argon storage keeps them stable
effect: The review reports degradation after 9 months of storage in air, and no degradation after 9 months in argon, citing the underlying work. Re-exposure to air converts one n-type film back to p-type.
rating: moderate
conditions:
atmosphere: air versus argon storage
duration: 9 months
source: pmc13413352
where: Atmospheric stability section; device table row citing reference 95
risks:
hazards:
- text: There are no UK statutory workplace exposure limits specifically for nanomaterials. The UK WEL for carbon black is not considered appropriate for CNTs, and the ACGIH graphite limit is not considered appropriate for graphene.
ghs: []
source: hsg272
where: Workplace exposure limits, paragraphs 25 to 27
- text: CNTs can be pure carbon or contain metals or residual catalyst. Long straight fibres should be assumed to have the potential to cause the health effects identified for biopersistent high aspect ratio nanomaterials, in the absence of evidence to the contrary.
ghs: []
source: hsg272
where: CNTs section
- text: Tangled, low-density fluffy bundles have no evidence so far of a hazard for the pleural cavity, but may still cause lung inflammation, and long-term effects of repeated exposure are not known.
ghs: []
source: hsg272
where: CNTs section
failure_risks:
- source: pubchem-carbon
where: Safety and Hazards, ICSC hazard note on dust explosion
mode: Dust explosions are possible when carbon powder is mixed with air,…
consequence: Dust explosions are possible when carbon powder is mixed with air, according to the ICSC note for carbon. This is for carbon powder in general, not CNT tested specifically.
side_effects: []
handling:
- text: HSE advises a precautionary risk management approach when workers may inhale CNTs or other biopersistent high aspect ratio nanomaterials.
source: hsg272
where: CNTs section, precautionary approach paragraph
mitigations: []
uses:
- application: electronics-and-chips
device: Fully printed all-carbon thermoelectric generator on flexible Kapton
example: The review describes an aqueous-processed generator that was bent and worn around a human arm as a wearable power source.
source: pmc13413352
where: Device examples, Example 1 and its flexibility test
- application: electronics-and-chips
device: Self-powered CNT composite strain sensor
example: A CNT composite sensor worn on a finger was tested at 90 and 180 degree bends, with its resistance response printed in Figure 13.
source: pmc13413352
where: Device examples, Figure 13 caption
supply:
- subject: Natural graphite (carbon feedstock, as used for graphite and graphene)
abundance: World mine production of natural graphite is 1,800,000 tons (2025 estimate) from 1,550,000 tons (2024). World reserves are 310,000,000 tons, of which China holds 100,000,000 tons. Rest-of-world resources are said to exceed 800 million tons of recoverable graphite.
producers:
- country: China
share_percent: 82
year: 2025
note: share of total world natural graphite production, 2025
critical_lists: []
import_reliance: Not stated for CNT-specific supply in the source read
source: usgs-graphite-2026
where: Graphite (Natural), Events, Trends and Issues; World Mine Production and Reserves table
- subject: Natural graphite imports to the United States
abundance: US natural graphite imports in 2025 were an estimated 79,000 tons (73.4 percent flake and high-purity).
producers:
- country: China (2021 to 2024 import share)
share_percent: 46
year: 2024
- country: Canada
share_percent: 13
year: 2024
- country: Mozambique
share_percent: 13
year: 2024
critical_lists: []
source: usgs-graphite-2026
where: Import Sources (2021 to 2024); Domestic Production and Use
media: []
documents:
- title: Thermal conduction of one-dimensional carbon nanomaterials and nanoarchitectures (arXiv 1803.06433)
type: paper
url: https://arxiv.org/pdf/1803.06433
year: 2018
- title: Thermal conduction phenomena in carbon nanotubes and related nanostructured materials (Reviews of Modern Physics, 2013)
type: paper
url: https://nanoheat.stanford.edu/wp-content/uploads/2013/09/RevModPhys-Marconnet-et-al..pdf
year: 2013
- title: PubChem record for Carbon, CID 5462310
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/5462310
year: 2026
- title: Review of carbon nanotube assemblies and CNT yarn properties (PMC7221842)
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC7221842
year: 2020
- title: 'USGS Mineral Commodity Summaries 2026: Graphite (Natural)'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf
year: 2026
- title: 'HSE HSG272: Using nanomaterials at work, including carbon nanotubes (CNTs) and other biopersistent high aspect ratio nanomaterials (HARNs)'
type: report
url: https://www.hse.gov.uk/pubns/books/hsg272.pdf
year: 2013
- title: Recent Advances in Air-Stable n-Type SWCNT Composites for Thermoelectric Applications (MDPI Materials, 2026)
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC13413352
year: 2026
gaps:
- 'Thermal conductivity of CNTs: values now read from arXiv 1803.06433 and the 2013 Marconnet review. The 6600 W m-1 K-1 value is a simulation prediction, not a measurement.'
- 'Story uses and the CNT-specific hazard data: story.uses is still empty. The PubChem record used (CID 5462310) is elemental carbon, not CNT; its dust-explosion note is carbon powder, not CNT-specific.'
- Seven sources reached against a target of 8. NASA NTRS CNT records, Nanocomp, OCSiAl and NIOSH were not reached in this run.
- 'Chirality and its effect on tube type: no numeric source read for chirality or the armchair and zigzag split. Only the qualitative statement in the HSE report was read.'
- 'Synthesis (arc discharge, CVD, HiPco): not read from a fetched primary source. The PMC review mentions only a supplier growth furnace with iron catalyst and a CVD-based direct spinning reference, and does not describe arc or HiPco. Search snippets were not used.'
- 'Nanocomp and OCSiAl datasheets not read: the curl download of the OCSiAl PDF returned an HTML error page and no Nanocomp datasheet URL was found. Cheap Tubes datasheet not located.'
- Single-tube electrical and thermal conductivity values not read from a fetched page.
- Oxidation onset temperature in air (TGA) for CNTs was not read. The 2026 synthesis paper has TGA profiles but its onset values are only in a figure, so no temperature is recorded. Ageing data come from one 2026 review on n-type SWCNTs.
- 'Uses: two thermoelectric device uses are sourced from a 2026 review. No CNT yarn or composite-structure use was read in this run, and the NASA CNT wire record was not found.'
- 'Health: NIOSH CNT criteria page returned empty or 404; no NIOSH limit is recorded. IARC CNT classification not read (the IARC URL redirected to an unrelated monograph). PubChem CNT record blocked by a browser check; no GHS statement recorded.'
- Only 3 sources were read in this run against a target of 8. Sources not reached are listed in documents only where read.
- Property name electrical_conductivity is not in spores/property-canon.yaml and was used as a short snake_case name.
sources:
pmc7221842:
title: CNT assembly and yarn property review (PMC7221842)
id: PMC7221842
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC7221842
year: 2020
kind: paper
license: Open access, as listed by PMC
usgs-graphite-2026:
title: 'Mineral Commodity Summaries 2026: Graphite (Natural)'
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf
year: 2026
kind: report
license: Public domain (US government)
hsg272:
title: Using nanomaterials at work, including carbon nanotubes (CNTs) and other biopersistent high aspect ratio nanomaterials (HARNs), HSG272
id: HSE HSG272
url: https://www.hse.gov.uk/pubns/books/hsg272.pdf
year: 2013
kind: report
license: Open Government Licence
pmc13413352:
title: Recent Advances in Air-Stable n-Type Single-Walled Carbon Nanotube Composites for Thermoelectric Applications (Materials, MDPI, 2026)
id: PMC13413352
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC13413352
year: 2026
kind: paper
license: Open access, as listed by PMC
arxiv-zhan-gu:
title: Thermal conduction of one-dimensional carbon nanomaterials and nanoarchitectures (arXiv 1803.06433)
id: arXiv 1803.06433
url: https://arxiv.org/pdf/1803.06433
year: 2018
kind: paper
license: arXiv preprint
marconnet-rmp:
title: Thermal conduction phenomena in carbon nanotubes and related nanostructured materials (Reviews of Modern Physics, 2013)
id: Marconnet, Panzer, Goodson
url: https://nanoheat.stanford.edu/wp-content/uploads/2013/09/RevModPhys-Marconnet-et-al..pdf
year: 2013
kind: paper
license: not stated on hosted copy
pubchem-carbon:
title: PubChem record for Carbon, CID 5462310 (CAS 7440-44-0)
id: CID 5462310
url: https://pubchem.ncbi.nlm.nih.gov/compound/5462310
year: 2026
kind: database
license: PubChem public data
license: CC-BY-4.0
updated: '2026-10-19'
review:
status: draft
method: assistant
checked_values: 18
unreachable: 5
caveats: 4
note: 'Written by an assistant on 2026-10-19 from three sources read in this run: a CNT assembly review (PMC7221842), USGS MCS 2026 graphite and HSE HSG272. Nanocomp, OCSiAl, Cheap Tubes, NIOSH, IARC, PubChem and NASA were not reached. Target of 8 sources not met.'
story:
recipe:
line: Carbon nanotubes are graphene sheets rolled into tubes, with every atom bonded to three neighbours in a hexagonal lattice. Single-wall tubes have one wall and multi-wall tubes have several coaxial walls. The review reads from a supplier growth furnace with iron catalyst nanoparticles, and cites a CVD-based direct spinning route for yarns. Arc discharge and HiPco were not read from a fetched source.
parts:
- name: Carbon
symbol: C
atoms: 1
atomic_weight: 12.011
role: The only element in a pure CNT. The tube wall is a rolled sheet of sp2-bonded carbon, so the material is pure carbon unless metal catalyst or contamination remains.
risk_groups:
- title: For people
level: 1
verdict: Handle as a precaution
lead: No nanomaterial exposure limit is set in the UK, and HSE advises a precautionary approach for CNTs that can be inhaled.
points:
- label: Inhalation
line: Long straight CNT fibres should be assumed to carry the health risks HSE identifies for biopersistent fibres. Tangled bundles may still cause lung inflammation.
why: Carbon nanotubes combine very high ideal strength and stiffness with electrical conduction. The values for ideal single tubes are theoretical. Macroscopic CNT yarns read here reach 0.8 GPa tensile strength and conduct at up to 8.5e6 S/m for the best reported assembly.
uses: []
can_do:
- label: Strength of CNT yarn
benchmark: ultimate_tensile_strength
line: Twisted CNT yarn reaches 0.8 GPa tensile strength and 14 GPa modulus, with 14 percent elongation to failure, in the review's Table 1. The ideal single-tube figure of 150 GPa is a theoretical limit, not a yarn value.
- label: Electrical conduction
benchmark: electrical_conductivity
line: As-received CNT yarn conducts at 100000 S/m, and twisted yarn at 500000 S/m. The best reported macroscopic CNT assembly reaches 8.5e6 S/m.
compare: Ideal single tubes are the strongest and stiffest values in this profile, but the macroscopic yarns read here are much weaker. Thermal conductivity of CNTs was not read in this run, so the profile does not compare heat conduction with graphene or metals.
compare_rows:
- label: Ideal tube tensile strength
benchmark: ultimate_tensile_strength
- label: Twisted yarn modulus
benchmark: elastic_modulus
- label: Yarn electrical conductivity
benchmark: electrical_conductivity
handling:
- Treat loose or powdered CNT material as a potential inhalation hazard, and use local exhaust ventilation.
- Check the supplier safety data sheet for the specific product, since residual catalyst and metal content vary.
good_for:
- Lightweight conductive yarns and assemblies, where the macroscopic conductivity and modulus values matter more than the ideal single-tube limit.
watch_out:
- Ideal single-tube values are theoretical and are far above the yarn values measured in the review.
- Thermal conductivity, ageing and space-use data are not in this profile.
- Inhalation risk from loose CNT material is not settled, and HSE says long-term effects of repeated exposure are not known.
verdict: Carbon nanotubes have very high ideal strength and stiffness on paper. The yarns read here are much weaker and conduct electricity well. This profile is a partial draft until the thermal, synthesis, health and space sources are read.
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 |
|---|---|---|---|---|
| CNT assembly and yarn property review (PMC7221842) | paper | 2020 | 16 values | |
| Mineral Commodity Summaries 2026: Graphite (Natural) | report | 2026 | 2 values | |
| Using nanomaterials at work, including carbon nanotubes (CNTs) and other biopersistent high aspect ratio nanomaterials (HARNs), HSG272 | report | 2013 | 4 values | |
| Recent Advances in Air-Stable n-Type Single-Walled Carbon Nanotube Composites for Thermoelectric Applications (Materials, MDPI, 2026) | paper | 2026 | 3 values | |
| Thermal conduction of one-dimensional carbon nanomaterials and nanoarchitectures (arXiv 1803.06433) | paper | 2018 | 2 values | |
| Thermal conduction phenomena in carbon nanotubes and related nanostructured materials (Reviews of Modern Physics, 2013) | paper | 2013 | 1 value | |
| PubChem record for Carbon, CID 5462310 (CAS 7440-44-0) | database | 2026 | 1 value |