3D Printing Info

Filament comparison

e-TPU vs TPU 98A

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

Foaming / expanded TPU (TPU Aero / TPU Air) guideTPU 98A / hard TPU guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore TPU 98A comparisons
e-TPU vs TPU 98A — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXTPU 98A / hard TPUFLEX
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$94.99/kg median; $34.99–$149.99/kg across 3 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]Hard thermoplastic polyurethane at 98 Shore A to about 60 Shore D — the rigid end of the TPU range[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]1.23 (Fillamentum Flexfill 98A); 1.2 (Extrudr FLEX HARD, ISO 2781)[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 150[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]95–150 across brands; Proto-pasta Clear Rigid TPU 95, Push Plastic TPU 100A 150[14][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[12][14][3]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][6][8][9][11]1.75 and 2.85 mm; 0.5, 0.75 and 1 kg spools[14][12]
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]Drive belts, wheels, snap-fits and bumpers that need to flex but hold shape under load[2]
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]230–260 (Extrudr FLEX HARD)[3]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][10]50–90 (Extrudr FLEX HARD)[3]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Open frame is fine[3]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]0–30 % (Extrudr FLEX HARD)[3]
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]PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent[15][16]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[8]4.6 (Extrudr FLEX HARD, stated max volumetric speed on a 0.4 mm nozzle)[3]
Warping tendency1–5Not documentedNone[3]
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]Not documented
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Easy — minor profile tuning; at this hardness the filament pushes like a rigid material[3]
Extruder requirementDirect drive; the base material is a 92A TPU[1][17]Bowden viable at this hardness — Extrudr rates FLEX HARD to 100 mm/s where its soft grades cap lower[3]
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[3][5]Brass fine indefinitely[3]
Abrasiveness1–5Non-abrasive[3]Non-abrasive[3]
Nozzle clog risk1–5Not documentedLow[18]
Heat-creep / jam sensitivity1–5Not documentedModerate — good heatbreak cooling needed[16]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[15]No special hot-end required, but a direct-drive extruder is (Simplify3D)[15]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[18]Moderate — the TPU family absorbs readily; Extrudr specifies a 12 h dry at 60 °C for FLEX HARD[3][18]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[10]Not documented
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][10]60 °C for 12 h (Extrudr FLEX HARD)[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[18][4]Bubbling and popping at the nozzle, stringing and a rough surface[18]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[18]Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[18]
Storage requirementSealed with desiccant; often kept in a dryer during the print[18]Sealed with desiccant; often kept in a dryer during the print[18]
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]53.7 at break (Fillamentum Flexfill 98A, DIN 53504)[2]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]Not documented
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]318 at break (Fillamentum Flexfill 98A, DIN 53504); Extrudr FLEX HARD 490 (ISO 527-2)[2][3]
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][4][5][19]98 Shore A and 60 Shore D (Fillamentum, ISO 7619-1); Extrudr FLEX HARD 58 Shore D (ISO 868)[2][3]
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[20]Poor — no 98A creep test; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[20]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[16]Excellent — living hinges viable[16]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Semi-flexible[2][3]
Wear resistance & frictionNot documentedAbrasion 23 mm³ (Fillamentum, ISO 4649 method A) and 26 mm³ (Extrudr FLEX HARD, ISO 4649-A) — the best abrasion figures in the group[2][3]
Thermal Properties
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]190–210 melting (Extrudr FLEX HARD, ISO 3146-C); Vicat A 140 (ISO 306)[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]Not documented
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[16]Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[16]
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[16]Withstands industrial solvents and UV exposure (Polymaker)[16]
Food contactNot food safe without specific certification (Polymaker)[16]Not food safe without specific certification (Polymaker)[16]
Biodegradability / compostabilityNot biodegradable[16]Not biodegradable[16]
RecyclabilityNot accepted in household plastic collection[16]Not accepted in household plastic collection[16]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[21]Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[21]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[21]Open a window / occasional ventilation[21]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[16]Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[16]
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[16]Cyanoacrylate bonds TPU; no common solvent welds it[16]
Vapour / chemical smoothingNo practical vapour smoothing[16]No practical vapour smoothing[16]
Support material pairingPolymaker warns TPU supports are often very difficult to remove[16]Polymaker warns TPU supports are often very difficult to remove[16]
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]Tear strength 170 kN/m (Fillamentum, ISO 34-1) and 175 kN/m (Extrudr FLEX HARD, ISO 34-1B)[2][3]
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[22]DMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[22]
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.[22]Toluene and benzene swell it up to +50 % by weight at 23 °C; esters swell it severely; ethanol and IPA soften it.[22]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[22]None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[22]

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. Flexfill TPU 98A Technical Data Sheet Fillamentum · 2019-08 · tds
  3. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · 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. Push Plastic product catalogue Push Plastic · 2026-08 · vendor
  13. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  14. Proto-pasta product catalogue Proto-pasta · 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. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  18. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  19. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  20. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  21. 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
  22. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds