3D Printing Info

Filament comparison

e-TPU vs PET-CF

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

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

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PET-CF comparisons
e-TPU vs PET-CF — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXCarbon-fibre PET (PET-CF)PETG
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$39.99/kg median; $26.00–$49.98/kg across 4 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]Semi-crystalline PET reinforced with carbon fibre — a different polymer from PETG-CF, with the glycol modifier removed so the matrix can crystallise[2][3]
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)[4][5]1.29 (Bambu Lab) and 1.34 (Fiberon PET-CF17), ISO 1183[2][3]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[6][7][8][9][10][11]1 kg spools cluster near 45[2][12]
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[6][7][8][9][10][11][13]26–50 across brands; ELEGOO 26 in a 5 kg pack, Bambu Lab 45, Fiberon 50[14][2][12]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][6][7][8][10][11]Available from several mainstream brands[2][12][14]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][6][8][9][11]1.75 mm; 0.5 and 1 kg spools[12][2]
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][9]Load-bearing parts that must survive above PETG's 70 °C ceiling without moving to PA or PC[2][3]
Diameter tolerance± mm0.03 (Siraya Tech and Roamr, 1.75 mm)[4][5]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][4][5][10]260–290 (Bambu Lab)[2]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][10]80–100 (Bambu Lab)[2]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Enclosure recommended — Bambu Lab specifies a 45–60 °C chamber[2]
Recommended chamber temperature°CNot documented45–60 (Bambu Lab)[2]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]0–60 % (Bambu Lab)[2]
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[15][16][4]Textured PEI, satin or powder-coated sheets; on smooth PEI a glue stick acts as a release agent[17][18]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[8]8 at Bambu Lab's 100 mm/s cap on a 0.4 mm nozzle at 0.2 mm layer — half the speed it allows for PETG-CF[2][19]
Bed-adhesion difficulty1–5Not documentedNeeds the right surface or a thin adhesive — the problem is releasing the part, not sticking it[17][18]
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[4][10]Moderate — retraction tuning needed; Polymaker names stringing as PETG's common quirk[18]
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Advanced — enclosure, hardware upgrades, tuning[2]
Extruder requirementDirect drive; the base material is a 92A TPU[1][20]Not documented
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[21][5]Hardened steel required[2]
Abrasiveness1–5Non-abrasive[21]Highly abrasive — standard CF composite[2]
Nozzle clog risk1–5Not documentedModerate — needs dry filament and a clean nozzle; Prusa lists higher risk of nozzle clogging for carbon-filled composites[22]
Heat-creep / jam sensitivity1–5Not documentedSlightly sensitive[23]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[15]No special hot-end required[23]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[24]Moderate — 0.37 % saturated at 25 °C / 55 % RH (Bambu Lab); 0.53 % equilibrium (Fiberon)[2][3]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[10]0.37 saturated at 25 °C / 55 % RH (Bambu Lab); 0.53 equilibrium (Fiberon PET-CF17)[2][3]
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][10]80 °C for 8–12 h (Bambu Lab) — the longest and hottest dry in the polyester family; Fiberon specifies 100 °C for 10 h[2][3]
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[24][4]Bubbling and popping at the nozzle, stringing and a rough surface[24]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[24]Bambu Lab publishes its whole mechanical table under the heading "Mechanical Properties (Dry state)" — the quoted figures apply only to dried filament[2]
Storage requirementSealed with desiccant; often kept in a dryer during the print[24]Sealed with desiccant; Polymaker groups PETG with the highly hygroscopic materials[24][18]
Hydrolysis at melt temperatureNot documentedThe 80–100 °C dry both suppliers mandate is far above the 55–65 °C used for PETG, consistent with a melt-hydrolysis risk in the semi-crystalline PET matrix; neither publishes a molecular-weight loss figure[2][3]
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][4][10]65.9 (Fiberon) to 74 (Bambu Lab) printed XY, ISO 527[2][3]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]4730 ± 260 (Bambu Lab) and 5481 ± 224 (Fiberon) printed XY, ISO 527[2][3]
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][4][5][10]2.4 ± 0.5 printed XY, ISO 527 (Fiberon PET-CF17)[3]
Flexural strengthMPaNot documented109.3 ± 2.0 printed XY, ISO 178 (Fiberon PET-CF17)[3]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]4744 ± 136 printed XY, ISO 178 (Fiberon PET-CF17)[3]
Charpy impact, notchedkJ/m²Not documented5.1 ± 0.2 printed XY, ISO 179 notched (Fiberon PET-CF17); unnotched 25.1 ± 2.8[3]
Layer adhesion / Z tensileMPaNot documented27.9 (Fiberon) and 35 ± 5 (Bambu Lab) printed Z, ISO 527[2][3]
Brittleness1–5Very ductile — bends far before failing[1]Very brittle — elongation at break 2.4 % in XY and 0.8 % in Z[3]
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][4][5][25]Not documented
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[26]Good — no creep test found; annealed PET-CF holds a 105 °C HDT at 1.8 MPa and a 4730–5481 MPa modulus against 1500–2311 for PETG[3][2]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[16]Below average — no S-N curve; elongation at break is 2.4 % in XY and 0.8 % in Z, against 5.2–9.3 % for unfilled PETG[3]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Rigid[2]
Z strength as % of XY%Not documented42 (Fiberon) to 47 (Bambu Lab), printed[2][3]
Thermal Properties
HDT at 0.45 MPa°CNot documented147.5 (Fiberon) and 205 (Bambu Lab), ISO 75 at 0.45 MPa[2][3]
HDT at 1.8 MPa°CNot documented105 (Fiberon) and 182 (Bambu Lab), ISO 75 at 1.8 MPa[2][3]
Glass transition (Tg)°CNot documented75 (Bambu Lab) and 79.3 (Fiberon), DSC[2][3]
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[4][10]241.3 (Fiberon) and 250 (Bambu Lab) melting, DSC; Vicat 226–238[2][3]
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][4]The PET matrix crystallises on annealing, which is what separates this grade from PETG-CF[3][2]
Flammability / UL 94Not documentedFlammable; no UL 94 rating published for standard grades[27]
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[16]Not documented
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[16]Withstands acids, alkalis, oils and UV exposure[18]
Food contactNot food safe without specific certification (Polymaker)[16]Not certified for food contact as filament[18]
Biodegradability / compostabilityNot biodegradable[16]Not biodegradable[18]
RecyclabilityNot accepted in household plastic collection[16]Not accepted in household plastic collection[18]
Electrical & ESD propertiesNot documentedSurface resistivity above 10¹² ohm — insulating (Fiberon PET-CF17, ANSI/ESD S11.11)[3]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[28]Moderate — measurable VOCs and UFPs, ventilation advised[28]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[28]Ventilated room or enclosure recommended[28][2]
Dust & fibre handling hazardNot documentedCarbon fibre is bound in the matrix; sanding dust should not be inhaled[3]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[16]Sands poorly — the material is tough and gums rather than powders[23]
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[16]Cyanoacrylate; no common solvent welds PETG cleanly[23]
Vapour / chemical smoothingNo practical vapour smoothing[16]No practical vapour smoothing[23]
Support material pairingPolymaker warns TPU supports are often very difficult to remove[16]Prints its own supports; Polymaker rates PolyDissolve S1 for PETG[23]
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][4]Bambu Lab markets it on low warping and shrinkage relative to other high-temperature composites[2]
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[29]None common; fluorinated solvents such as hexafluoroisopropanol dissolve linear polyester at 23 °C. Laboratory only.[30][31]
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.[29]Ensinger rates polyester not resistant to chloroform or dichloromethane and only conditionally resistant to acetone and MEK.[31]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[29]Dichloromethane attacks polyester and can be brushed on, but the carbon fibre blocks any useful surface flow.[31][32]

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. Bambu Filament Technical Data Sheet — PET-CF Bambu Lab · 2026-08 · tds
  3. Fiberon PET-CF17 Technical Data Sheet V1.0 Polymaker · 2026-08 · tds
  4. Siraya Tech Flex TPU Air Technical Data Sheet Siraya Tech · 2026-08 · tds
  5. Roamr TPU Air HR 80A Technical Data Sheet Siraya Tech · 2026-08 · tds
  6. Recreus product catalogue Recreus · 2026-08 · vendor
  7. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  8. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  9. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  10. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  11. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  12. Polymaker product catalogue Polymaker · 2026-08 · vendor
  13. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  14. ELEGOO product catalogue ELEGOO · 2026-08 · vendor
  15. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  16. TPU — material basics Polymaker Wiki · 2026-08 · doc
  17. Prusament PETG Technical Datasheet v1.1 Prusa Polymers · 2022-02 · tds
  18. PETG — material basics Polymaker Wiki · 2026-08 · doc
  19. Max volumetric speed Prusa Knowledge Base · 2026-08 · doc
  20. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  21. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  22. Composite materials filled with carbon, kevlar or glass Prusa Knowledge Base · 2026-08 · doc
  23. PET and PETG — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  24. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  25. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  26. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  27. Prusament PETG V0 Technical Datasheet Prusa Polymers · 2026-08 · tds
  28. 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
  29. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  30. Resistance of Ultramid, Ultraform and Ultradur to chemicals (TI-KTU/AS-28 e) BASF · 2000-10 · tds
  31. Chemical resistance — resistance of Ensinger plastics to chemicals (DIN 50 014, 23/50) Ensinger · 2026-08 · tds
  32. Improve your 3D prints with chemical smoothing Prusa Research · 2026-08 · doc