3D Printing Info

Filament comparison

e-TPU vs PSU

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

Foaming / expanded TPU (TPU Aero / TPU Air) guidePSU guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PSU comparisons
e-TPU vs PSU — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXPSUHIGHTEMP
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$168.00/kg median; $168.00–$168.00/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]Polysulfone — the lowest-temperature and cheapest of the sulfone family[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]1.24 (ISO 1183)[2]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[5][6][7][8][9][10]1 kg-equivalent spools cluster near 250[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]168-250 across formats; 250 g spool $42 (168/kg), 500 g $125 (250/kg) — 3DXTech is the only filament supplier 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]Special order, 1–2 makers worldwide[11]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][5][7][8][10]1.75 mm; 250 g and 500 g spools[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]Transparent high-temperature housings, medical trays and hot-water fittings[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]Not documented
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[3][4][9]120–140 (3DXTech)[2]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][4]Actively heated chamber required[13][14]
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[15][16][3]Not documented
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[7]Not documented
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]Expert / industrial hardware only[13][14]
Extruder requirementDirect drive; the base material is a 92A TPU[1][17]Not documented
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[18][4]Brass fine indefinitely for unfilled grades, but brass softens near these nozzle temperatures — hardened or plated hot ends are the norm[13]
Abrasiveness1–5Non-abrasive[18]Non-abrasive when unfilled[2]
Nozzle clog risk1–5Not documentedModerate — needs dry filament and a clean nozzle; 3DXTech lists no special nozzle concerns but a mandatory 120 °C pre-dry before every print[19]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[15]Not documented
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[20]Not documented
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[9]0.30 in 24 h on extruded stock (ASTM D570)[21]
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[3][4][9]Not documented
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[20][3]Not documented
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[20]No dry-versus-conditioned figures are published; 3DXTech mandates a 120 °C, 4 h pre-dry before every print because trapped water flashes to steam at these nozzle temperatures[19]
Storage requirementSealed with desiccant; often kept in a dryer during the print[20]Not documented
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]52 (printed XY, ISO 527, 3DXTech); 81 at break on extruded stock (ASTM D638)[2][21]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]2100 (printed XY, ISO 527)[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]8 (printed XY, ISO 527) against 50 on extruded stock — nearly three times PPSU's printed 3 %[2][22][21]
Flexural strengthMPaNot documented87 (printed XY, ISO 178)[2]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]2050 (printed XY, ISO 178)[2]
Other impact dataNot documentedIzod notched 69 J/m on extruded PSU stock, converted from 1.3 ft-lb/in (ASTM D256)[21]
Brittleness1–5Very ductile — bends far before failing[1]Moderate[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][23]Rockwell M120 on extruded PSU stock (ASTM D785)[21]
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[24]Good. Ensinger lists high creep resistance as a headline property of extruded PSU stock, which is rated to 173 °C heat deflection at 1.8 MPa[21]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[16]Not documented
Elasticity / flexibility1–5Rubbery / highly elastic[1]Rigid[2]
Thermal Properties
HDT at 0.45 MPa°CNot documented172 (printed XY, ISO 75 at 0.45 MPa, 3DXTech); 181 on extruded stock, converted from 358 °F at 66 psi[2][21]
HDT at 1.8 MPa°CNot documented174 on extruded PSU stock, converted from 345 °F at 264 psi (ASTM D648)[21]
Glass transition (Tg)°CNot documented187 (DSC, 3DXTech) and 185 on extruded stock (ASTM D3418), against 230 for PPSU[2][22][21]
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]Not documented
Continuous service temperature°CNot documented141 long-term service on extruded PSU stock, converted from 285 °F[21]
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
Thermal expansion (CTE)µm/m·KNot documented55.8 (extruded PSU stock, ASTM D696; source states 3.1e-5 in/in/°F)[21]
Flammability / UL 94Not documentedUL 94 V-0 on extruded PSU stock[21]
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]Not documented
Food contactNot food safe without specific certification (Polymaker)[16]Not documented
Biodegradability / compostabilityNot biodegradable[16]Not documented
RecyclabilityNot accepted in household plastic collection[16]Not documented
Electrical & ESD propertiesNot documentedSurface resistance above 10¹³ ohm/sq — an insulator (IEC 60093)[2]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[25]Moderate — measurable VOCs and UFPs, ventilation advised. None of these polymers was in the chamber study, and all are processed far above the temperatures it covered[25]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[25]Ventilated room or enclosure recommended[25]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[16]Not documented
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[16]Not documented
Vapour / chemical smoothingNo practical vapour smoothing[16]Not documented
Support material pairingPolymaker warns TPU supports are often very difficult to remove[16]Not documented
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]Not documented
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[26]Chlorinated hydrocarbons — dichloromethane, chloroform — dissolve polysulfone; ketones and esters attack it as well.[27][28]
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.[26]Acetone, MEK, ethyl acetate, benzene and toluene craze or stress-crack it; methanol and isopropanol only marginally.[28][27]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[26]Dichloromethane cement welds PSU and NMP softens residual resin. Both are laboratory reagents.[27]

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. ThermaX PSU Technical Data Sheet v3 3DXTech · 2026-08 · 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. 3DXTech product catalogue 3DXTech · 2026-08 · vendor
  12. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  13. Prusament PEI 1010 Technical Datasheet v1.0 Prusa Polymers · 2024-09 · tds
  14. Prusament PEI 1010 — material page Prusa Polymers · 2026-08 · doc
  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. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  19. THERMAX PSU — product page (print recommendations) 3DXTech · 2026-08 · doc
  20. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  21. TECASON S natural (PSU) — stock shape properties Ensinger · 2026-08 · tds
  22. ThermaX PPSU Technical Data Sheet v3 3DXTech · 2026-08 · tds
  23. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  24. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  25. 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
  26. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  27. Radel PPSU, Veradel PESU, Acudel modified PPSU Design Guide — environmental stress cracking tables Solvay Specialty Polymers · 2026-08 · tds
  28. Chemical resistance — resistance of Ensinger plastics to chemicals (DIN 50 014, 23/50) Ensinger · 2026-08 · tds