3D Printing Info

Filament comparison

e-TPU vs PPA

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

Foaming / expanded TPU (TPU Aero / TPU Air) guidePPA (polyphthalamide) guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PPA comparisons
e-TPU vs PPA — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXPPA (polyphthalamide)PA
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$45.49/kg median; $45.49–$45.49/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]Polyphthalamide — a semi-aromatic polyamide in which aromatic diacid units replace part of the aliphatic backbone; Raise3D and Bambu Lab both label it high-temperature nylon[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]1.21 (ISO 1183, Siraya Tech Fibreheart PPA)[6]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[7][8][9][10][11][12]One 1 kg listing on the market, at 45[13]
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[7][8][9][10][11][12][14]45 for the only unfilled PPA filament found — Siraya Tech Fibreheart PPA at 1 kg; every other PPA in retail is carbon- or glass-filled[13]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][7][8][9][11][12]Special order, 1–2 makers worldwide — Siraya Tech is the only brand found selling unfilled PPA filament[13]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][7][9][10][12]1.75 mm, 1 kg[13]
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][10]Gears, bearings and tooling that must hold load above the reach of PA6 or PA12, and parts exposed to fuels and industrial chemicals[6]
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][11]280–300 (Siraya Tech)[6]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][11]70–80 (Siraya Tech)[6]
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Enclosure recommended — Siraya Tech advises an enclosure to hold temperature and limit warping on larger prints[6]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]20–60 % (Siraya Tech)[6]
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 with a glue stick, or a PVP glue coating[6]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[9]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[4][11]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; needs a 300 °C-class hot end and a dry spool[6]
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][5]Brass fine indefinitely — Siraya Tech states a hardened steel nozzle is not needed for the unfilled grade[6]
Abrasiveness1–5Non-abrasive[18]Non-abrasive when unfilled[6]
Nozzle clog risk1–5Not documentedModerate — needs dry filament and a clean nozzle; Siraya Tech tells users to dry only when moisture symptoms appear, rather than before every print[6]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[15]High-quality metal nozzle, 0.4–1.0 mm; hardened steel not required (Siraya Tech)[6]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[19]High (0.8–2 %) — Siraya Tech publishes 2.59 % by ISO 62 immersion for the unfilled grade; on the equilibrium basis Bambu Lab uses, its 15 % carbon-filled PPA reaches 1.30 % against 2.35 % for the same maker's PA6-CF[6][3][20]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[11]2.59 by ISO 62 water immersion (Siraya Tech, unfilled) — an immersion figure, not the 25 °C / 55 % RH equilibrium basis the filled grades are quoted on, so the two are not directly comparable[6]
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][11]80–100 °C for 4–6 h (Siraya Tech)[6]
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[19][4]Oozing, bubbles and a rough surface finish (Siraya Tech)[6]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[19]Siraya Tech publishes dry against saturated for the same grade: tensile 70 → 60 MPa, flexural 114 → 87 MPa, HDT at 1.8 MPa 73.5 → 48.5 °C, while Charpy rises 10 → 14.5 kJ/m²[6][13]
Storage requirementSealed with desiccant; often kept in a dryer during the print[19]Dry box below 15 % RH (Siraya Tech)[6]
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][11]72 at break (printed, ASTM D638, Siraya Tech); the product page quotes 70 dry and 60 saturated[6][13]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]3600 (printed, ASTM D638, Siraya Tech)[6]
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][11]10.5 at break (printed, ASTM D638, Siraya Tech)[6]
Flexural strengthMPaNot documented115 (printed, ISO 178, Siraya Tech); 114 dry against 87 saturated on the product page[6][13]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]3350 (printed, ISO 178, Siraya Tech)[6]
Charpy impact, notchedkJ/m²Not documented10.1 Charpy (printed, ISO 179, Siraya Tech); the data sheet does not state whether the specimen was notched[6]
Brittleness1–5Very ductile — bends far before failing[1]Moderate — 10.5 % elongation at break puts it between PA6 and the fibre-filled grades[6]
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][21]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[22]Good — Raise3D cites high creep resistance as a reason to choose the PPA matrix over other nylons[2]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[16]Not documented
Elasticity / flexibility1–5Rubbery / highly elastic[1]Rigid — 3.6 GPa tensile modulus[6]
Wear resistance & frictionNot documentedSiraya Tech describes the unfilled grade as low-friction and self-lubricating, aimed at gears and bearings[6][13]
Thermal Properties
HDT at 0.45 MPa°CNot documented81 dry and 61 saturated (printed, ISO 75 Method B at 0.45 MPa, Siraya Tech)[6]
HDT at 1.8 MPa°CNot documented73.5 dry and 48.5 saturated (printed, ISO 75 Method A at 1.8 MPa, Siraya Tech) — unfilled PPA deflects near its Tg; the 190–227 °C figures quoted for PPA are carbon-filled grades[6][3]
Glass transition (Tg)°CNot documented80 (ASTM D3418, Siraya Tech)[6]
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][11]231 melting point (ASTM D3418) and 230 Vicat (ISO 306), Siraya Tech[6]
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]Siraya Tech's product page offers annealing for strength while its own data sheet says annealing is not recommended because the print can warp; on its 15 % carbon-filled PPA, annealing lifts HDT at 1.8 MPa from 82.5 to 119 °C[6][13][23]
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 fuels, oils and industrial chemicals; Bambu Lab rates semi-aromatic nylon better than general nylon against weak acids, weak alkalis and most organic solvents[6][3]
Water / humidity resistance in service1–5Not documentedAbsorbs water, properties shift — a saturated specimen loses about 15 % of its tensile strength and 25 °C of heat-deflection temperature[6][13]
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
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[24]Not documented
Ventilation / filtration requirement1–5Open a window / occasional ventilation[24]Not documented
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]Compatible with quick-release support materials (Siraya Tech)[6]
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.[25]Dissolved at 23 °C by formic acid, phenol, m-cresol, 96 % sulphuric acid or hexafluoroisopropanol — all laboratory reagents.[26]
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.[25]Mineral acids, oxidants, halogens and zinc chloride solutions attack the amide bond; ordinary solvents do not.[26]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[25]None — nylon's only solvents are formic acid, phenol and HFIP, all of which degrade the part they wet.[26]

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. Raise3D Industrial PPA CF Technical Data Sheet V2.0 Raise3D · 2022-04 · tds
  3. Bambu Filament Technical Data Sheet V1.0 — PPA-CF Bambu Lab · 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. Siraya Tech Fibreheart PPA Technical Data Sheet Siraya Tech · 2026-08 · tds
  7. Recreus product catalogue Recreus · 2026-08 · vendor
  8. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  9. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  10. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  11. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  12. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  13. Siraya Tech Fibreheart PPA Filament — product page Siraya Tech · 2026-08 · vendor
  14. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 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. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  19. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  20. Bambu Filament Technical Data Sheet V3.0 — PA6-CF Bambu Lab · 2026-08 · tds
  21. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  22. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  23. Siraya Tech Fibreheart PPA-CF Technical Data Sheet Siraya Tech · 2026-08 · tds
  24. 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
  25. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  26. Ultramid Nylon Chemical Resistance guide (unmodified PA6 B27E and PA66 A27E) BASF · 2026-08 · tds