3D Printing Info

Filament comparison

e-TPU vs PA blend

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

Foaming / expanded TPU (TPU Aero / TPU Air) guidePA6/66 copolymer blends guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PA blend comparisons
e-TPU vs PA blend — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXPA6/66 copolymer blendsPA
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$65.62/kg median; $62.00–$113.33/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]PA6/66 copolymer — a nylon alloy that lowers the melting point and improves printability against straight PA6[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]1.12 (ISO 1183, Polymaker CoPA)[2]
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-equivalent spools cluster near 65[12][13][14]
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][15]62–113 across brands; add:north Adura 62, PrimaCreator NylonPower PA6/66 65 at 500 g, Polymaker CoPA 67, 3DXTech AmideX Nylon 6-66 113[12][16][13][14]
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][16]
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[12][16][13][14]
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]General-purpose nylon parts and, unusually, CoPA can support itself if the support is removed before it absorbs moisture[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]250–270 (Polymaker CoPA)[2]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][10]25–50 (Polymaker CoPA)[2]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Enclosure required (passive) — Polymaker specifies a chamber at ambient temperature[2]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]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[17][18][4]Not documented
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[8]16 at Polymaker's 200 mm/s cap on a 0.4 mm nozzle at 0.2 mm layer[2][19]
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]Advanced — enclosure, hardware upgrades, tuning; must be kept below 20 % RH throughout[2][20]
Extruder requirementDirect drive; the base material is a 92A TPU[1][21]Not documented
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[22][5]Brass fine indefinitely for unfilled grades[23]
Abrasiveness1–5Non-abrasive[22]Non-abrasive when unfilled[23]
Nozzle clog risk1–5Not documentedVery high — frequent jams without careful setup[24][20]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[17]Not documented
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[20]Very high (>2 %) — Polymaker's own wet-state specimens reached 6.16 % moisture content after 48 h immersion at 60 °C[2][20]
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]100 °C for 8 h (Polymaker CoPA)[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[20][4]Popping and cracking during extrusion, then hard-to-diagnose defects[24]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[20]Measured dry against wet on printed specimens at 6.16 % moisture (Polymaker CoPA): tensile 78.0 → 34.3 MPa, Young's modulus 2703 → 724 MPa, flexural strength 109.8 → 22.6 MPa, while notched Charpy rises 6.9 → 27.7 kJ/m² and elongation 12.7 → 13.2 %[2][24]
Storage requirementSealed with desiccant; often kept in a dryer during the print[20]Polymaker states CoPA must always be stored and used below 20 % relative humidity[2]
Hydrolysis at melt temperatureNot documentedPolymaker requires a 100 °C dry for 8 h and storage below 20 % RH; no molecular-weight loss figure is published, and the published wet data is conditioning rather than melt hydrolysis[2][25]
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]78.0 ± 0.7 printed XY dry and 34.3 ± 2.5 wet, ISO 527 (Polymaker CoPA)[2]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]2703 ± 259 printed XY dry and 724 ± 61 wet, ISO 527 (Polymaker CoPA)[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][4][5][10]12.7 ± 2.1 printed XY dry and 13.2 ± 2.3 wet, ISO 527 (Polymaker CoPA)[2]
Flexural strengthMPaNot documented109.8 ± 1.3 printed XY dry and 22.6 ± 0.5 wet, ISO 178 (Polymaker CoPA)[2]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]2510 ± 25 printed XY dry and 636 ± 11 wet, ISO 178 (Polymaker CoPA)[2]
Charpy impact, notchedkJ/m²Not documented6.9 ± 1.4 printed XY dry and 27.7 ± 1.2 wet, ISO 179 notched (Polymaker CoPA) — impact quadruples when conditioned[2]
Layer adhesion / Z tensileMPaNot documented45.8 ± 1.5 printed Z dry, falling to 13.7 ± 1.2 wet, ISO 527 (Polymaker CoPA)[2]
Brittleness1–5Very ductile — bends far before failing[1]Tough — absorbs impact, yields before breaking[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][26]Shore D 86 and Rockwell 85 (108) — the source does not name the scales on extruded unfilled PA66 stock (ASTM D2240, D785)[27]
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[28]Not documented
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[18]Excellent — living hinges viable[23]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Semi-flexible[24]
Z strength as % of XY%Not documented59 dry (45.8 Z against 78.0 XY) and 40 wet, printed[2]
Thermal Properties
HDT at 0.45 MPa°CNot documented111 (ISO 75, 0.45 MPa, Polymaker CoPA)[2]
HDT at 1.8 MPa°CNot documented70 (ISO 75, 1.8 MPa, Polymaker CoPA)[2]
Glass transition (Tg)°CNot documented66 (DSC, Polymaker CoPA)[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[4][10]189 melting (DSC); Vicat 180, crystallisation 148, decomposition 370 (Polymaker CoPA)[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][4]80 °C for 6 h (Polymaker CoPA)[2]
Thermal expansion (CTE)µm/m·KNot documented81.0 on extruded unfilled PA66 stock (ASTM D696; source states 4.5e-5 in/in/°F) — the same chemistry as a PA6/66 copolymer[27]
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[18]Not documented
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[18]Not documented
Water / humidity resistance in service1–5Not documentedAbsorbs water, properties shift — 6.16 % uptake cost 56 % of tensile strength and 73 % of modulus[2]
Food contactNot food safe without specific certification (Polymaker)[18]Not documented
Biodegradability / compostabilityNot biodegradable[18]Not documented
RecyclabilityNot accepted in household plastic collection[18]Not documented
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[29]Moderate — measurable VOCs and UFPs, ventilation advised[29]
VOC emission rateµg/minNot documentedUp to 180 caprolactam, the dominant VOC from nylon; total VOC reached nearly 200 µg/min, the highest of the nine filaments tested[29]
Ultrafine-particle emission rateparticles/minNot documented≈2 × 10⁸ median — low for ultrafine particles despite the highest VOC mass of any filament tested[29]
Hazardous species emittedNot documentedCaprolactam, at up to 180 µg/min from nylon filament — the largest single-VOC emission rate measured in the study[29]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[29]Ventilated room or enclosure recommended[29]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[18]Not documented
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[18]Not documented
Vapour / chemical smoothingNo practical vapour smoothing[18]Not documented
Support material pairingPolymaker warns TPU supports are often very difficult to remove[18]CoPA can support itself, but Polymaker warns the support bonds permanently if it absorbs moisture before removal[2]
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]Not documented
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[30]Dissolved at 23 °C by formic acid above ~50 %, phenol, m-cresol, 96 % sulphuric acid or hexafluoroisopropanol — laboratory reagents.[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.[30]Zinc chloride solutions stress-crack it — 10 % marginal, 37 % not resistant; alcoholic calcium chloride dissolves it.[31]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[30]None — nylon's only solvents are formic acid, phenol and HFIP, all of which degrade the part they wet.[31]

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. PolyMide CoPA Technical Data Sheet V5.4 (dry and wet status blocks) Polymaker · 2024-11 · tds
  3. AmideX Nylon 6-66 — product page 3DXTech · 2026-08 · vendor
  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. add:north Adura product page add:north · 2026-08 · vendor
  14. PrimaCreator SELECT NylonPower PA6/66 product page PrimaCreator · 2026-08 · vendor
  15. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  16. 3DXTech product catalogue 3DXTech · 2026-08 · vendor
  17. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  18. TPU — material basics Polymaker Wiki · 2026-08 · doc
  19. Max volumetric speed Prusa Knowledge Base · 2026-08 · doc
  20. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  21. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  22. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  23. PA (Nylon) — material basics Polymaker Wiki · 2026-08 · doc
  24. Moisture Conditioning — effect on printed nylon properties Polymaker Wiki · 2026-08 · doc
  25. PolyMide CoPA — Technical Data Sheet page Polymaker Wiki · 2026-08 · tds
  26. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  27. TECAMID 66 natural (PA66) — stock shape properties Ensinger · 2026-08 · tds
  28. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  29. 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
  30. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  31. Ultramid Nylon Chemical Resistance guide (unmodified PA6 B27E and PA66 A27E) BASF · 2026-08 · tds