3D Printing Info

Filament comparison

e-TPU vs TPU-CF

Compare printing settings, strength, heat resistance, dated prices and sources.

Foaming / expanded TPU (TPU Aero / TPU Air) guideCarbon-fibre TPU guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore TPU-CF comparisons
e-TPU vs TPU-CF — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXCarbon-fibre TPUFLEX
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$107.05/kg median; $107.05–$107.05/kg across 1 dated product listings
Identity & Market
Base polymer / chemistryFoaming thermoplastic polyurethane — a blowing agent expands the extrudate so the printed Shore hardness can be tuned by flow rate[1]Carbon-fibre reinforced thermoplastic polyurethane at the hard end of the range[2]
Densityg/cm³1.15 filament (Siraya Tech Flex TPU Air) and 1.05 (Roamr TPU Air HR), ISO 1183; the printed part falls to 0.51–0.93 depending on nozzle temperature (ISO 845)[3][4]1.22 (Extrudr FLEX HARD CF, ISO 2781)[2]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[5][6][7][8][9][10]107 for the only retail listing found (Extrudr 0.5 kg coil, incl. VAT)[11]
Price range across brandsUSD/kg42–85 across brands; QIDI TPU-Aero 42, Siraya Tech Flex TPU Air 45, Phaetus aeFlex TPU-Aero 49 direct and 40 at West3D, Roamr TPU Air HR 80A 55 at 800 g, Recreus Filaflex Foamy 73 at 750 g, colorFabb varioShore 85 at 700 g[5][6][7][8][9][10][12]One listing only: EUR 49.56 incl. VAT per 0.5 kg coil, direct from Extrudr; no reseller or second brand found[11]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][5][6][7][9][10]Niche, a handful of specialist brands — Extrudr's FLEX HARD CF is the only carbon-filled flexible with a published datasheet found here[2]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][5][7][8][10]1.75 mm; 0.5 and 2 kg coils[11]
Typical applicationsCushioning, midsoles, insoles and soft-touch parts where the softness needs to vary within one print; Siraya Tech's Roamr line is aimed specifically at printed footwear[1][8]Stiffened flexible parts — damping mounts and semi-rigid brackets[2]
Diameter tolerance± mm0.03 (Siraya Tech and Roamr, 1.75 mm)[3][4]Not documented
Printing Parameters
Nozzle temperature°C230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range[1][3][4][9]230–260 (Extrudr FLEX HARD CF)[2]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[3][4][9]50–90 (Extrudr FLEX HARD CF)[2]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][4]Open frame is fine[2]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[3][4]Not documented
Bed surface & adhesion aidPEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent, and Siraya Tech recommends PVP glue or Magigoo as a release agent on PEI[13][14][3]PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent[13][14]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[7]1.6–8 at the 20–100 mm/s Extrudr specifies on a 0.4 mm nozzle at 0.2 mm layer[2]
Stringing / oozing tendency1–5Severe — the material expands inside the hot end, so it oozes on travel moves; QIDI states retraction tuning cannot fix it and Siraya Tech advises setting retraction distance and speed to zero[3][9]Not documented
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Advanced — enclosure, hardware upgrades, tuning; hardened nozzle needed[2]
Extruder requirementDirect drive; the base material is a 92A TPU[1][15]Not documented
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[2][4]Hardened steel required — Extrudr marks FLEX HARD CF as needing a hardened nozzle where its unfilled FLEX grades do not[2]
Abrasiveness1–5Non-abrasive[2]Highly abrasive — standard CF composite[2]
Nozzle clog risk1–5Not documentedHigh — jams from moisture, heat creep or particles; a flexible base plus chopped carbon fibre, which Prusa lists as a higher nozzle-clogging risk, and Extrudr requires a hardened nozzle[16][2][13]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[13]No special hot-end required, but a direct-drive extruder is (Simplify3D)[13]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[17]Moderate[17]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[9]Not documented
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[3][4][9]60 °C for 6 h (Extrudr FLEX HARD CF)[2]
Symptoms when wetBubbling and popping at the nozzle, stringing and a rough surface; Siraya Tech adds that moisture wrecks the foaming itself, not only the surface[17][3]Bubbling and popping at the nozzle, stringing and a rough surface[17]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[17]Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[17]
Storage requirementSealed with desiccant; often kept in a dryer during the print[17]Sealed with desiccant; often kept in a dryer during the print[17]
Mechanical Properties
Tensile strength (XY)MPaFalls with foaming: colorFabb 24 unfoamed and 12 foamed (ISO 527-1A); Siraya Tech 10.3 at break printed at 240 °C down to 3.8 at 270 °C; QIDI 6.81 at break (ISO 527, XY)[1][3][9]Not documented
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]35 (Extrudr FLEX HARD CF, ISO 527-2/5A/500)[2]
Elongation at break%465 unfoamed and 450 foamed (colorFabb, ISO 527-1A); Siraya Tech 629 at 240 °C down to 475 at 270 °C; Roamr 760 down to 540; QIDI 576 (ISO 527, XY)[1][3][4][9]380 ultimate elongation (Extrudr FLEX HARD CF, ISO 527-2/5A/500), against 490 for the unfilled FLEX HARD[2]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]Not documented
Brittleness1–5Very ductile — bends far before failing[1]Very ductile — bends far before failing[2]
Hardness (scale-specific)Shore A / Shore D / RockwellTunable by nozzle temperature: colorFabb 92 Shore A unfoamed; Siraya Tech 78 A printed at 240 °C falling to 63 A at 270 °C, Roamr TPU Air HR 80A 80 A down to 66 A and HR 85A 83 A down to 70 A (ISO 7619)[1][3][4][18]70 Shore D (Extrudr FLEX HARD CF, ISO 868), against 58 Shore D for the unfilled FLEX HARD[2]
Creep resistance / sustained load1–5Poor — no foamed-grade creep test; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[19]Below average — no CF-grade creep test; the grade is 70 Shore D where a 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[2][19]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[14]Good — 380 % ultimate elongation and a damping application set (Extrudr cites longboard wheels), below the unfilled grades[2]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Semi-flexible[2]
Wear resistance & frictionNot documentedAbrasion 26 mm³ (Extrudr FLEX HARD CF, ISO 4649-A) — the same as the unfilled FLEX HARD[2]
Thermal Properties
Glass transition (Tg)°CNot documented-24 (Extrudr FLEX HARD CF)[2]
Melting point / Vicat°CVicat softening drops as the foam expands: 83 printed at 240 °C to 53 at 270 °C (Siraya Tech, ISO 306); QIDI 70.4[3][9]Vicat A 140 (Extrudr FLEX HARD CF, ISO 306)[2]
Annealing responseFoaming activates near 230 °C and expands the extrudate about 1.6×; colorFabb advises dropping flow to 60–70 % to realise the weight saving, and Siraya Tech publishes a flow schedule from 85–90 % at 230 °C down to 50–55 % at 270 °C[1][3]Not documented
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[14]Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[14]
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[14]Withstands industrial solvents and UV exposure (Polymaker)[14]
Food contactNot food safe without specific certification (Polymaker)[14]Not food safe without specific certification (Polymaker)[14]
Biodegradability / compostabilityNot biodegradable[14]Not biodegradable[14]
RecyclabilityNot accepted in household plastic collection[14]Not accepted in household plastic collection[14]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[20]Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[20]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[20]Open a window / occasional ventilation[20]
Dust & fibre handling hazardNot documentedCarbon fibre is bound in the matrix; sanding dust should not be inhaled[2]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[14]Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[14]
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[14]Cyanoacrylate bonds TPU; no common solvent welds it[14]
Vapour / chemical smoothingNo practical vapour smoothing[14]No practical vapour smoothing[14]
Support material pairingPolymaker warns TPU supports are often very difficult to remove[14]Polymaker warns TPU supports are often very difficult to remove[14]
Dimensional accuracy & detailFoamed surfaces are matte and textured; holding a consistent hardness means holding the nozzle temperature steady, and the printed density moves by nearly a factor of two across the 230–270 °C window[1][3]Tear strength 165 kN/m (Extrudr FLEX HARD CF, ISO 34-1B)[2]
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[21]DMF, DMSO, NMP and THF dissolve the TPU matrix and leave the fibre; ketones are partial solvents. Laboratory reagents.[21]
Softened or crazed byToluene and benzene swell it up to +50 % by weight at 23 °C; the foamed wall soaks up esters and alcohols faster still.[21]Toluene and benzene swell it up to +50 % by weight at 23 °C; esters swell it severely; ethanol and IPA soften it.[21]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[21]None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[21]

Material entries describe families or representative grades, not an interchangeable specification for every spool. Test methods, orientations and conditions may differ. Unknown values are marked “Not documented”. Prices and source dates remain historical snapshots; check the linked guide for product details. Differences highlight text, not a universal winner.

Sources for this comparison

  1. varioShore TPU Technical Data Sheet colorFabb · 2026-08 · tds
  2. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  3. Siraya Tech Flex TPU Air Technical Data Sheet Siraya Tech · 2026-08 · tds
  4. Roamr TPU Air HR 80A Technical Data Sheet Siraya Tech · 2026-08 · tds
  5. Recreus product catalogue Recreus · 2026-08 · vendor
  6. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  7. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  8. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  9. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  10. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  11. Extrudr TPU FLEX Hard CF — product page (1.75 mm, 0.5 and 2 kg coils, price) Extrudr (FD3D GmbH) · 2026-08 · vendor
  12. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  13. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  14. TPU — material basics Polymaker Wiki · 2026-08 · doc
  15. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  16. Composite materials filled with carbon, kevlar or glass Prusa Knowledge Base · 2026-08 · doc
  17. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  18. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  19. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  20. Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments (Azimi et al.) Environmental Science & Technology 50(3) 1260-1268 · 2016-01 · paper
  21. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds