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.