3D Printing InfoFilament comparison
PA6/66 vs TPU soft
Compare printing settings, strength, heat resistance, dated prices and sources.
2 selected · all documented properties
| Property | PA66 (Nylon 66)PA | Soft TPU (below 85A)FLEX |
|---|---|---|
| Market snapshot | ||
| Listing priceUSD/kg; dated snapshots | Not documented | $114.04/kg median; $109.80–$122.27/kg across 4 dated product listings |
| Identity & Market | ||
| Base polymer / chemistry | Polyamide 66, condensed from hexamethylenediamine and adipic acid; melts around 40 °C above PA6[1] | Very soft thermoplastic elastomers below 85 Shore A. Fiberlogy's FiberFlex 30D measures 81 Shore A, the softest grade with a published datasheet found here[2] |
| Densityg/cm³ | 1.14 (extruded unfilled PA66 stock)[3] | 1.07 (Fiberlogy FiberFlex 30D, ISO 1183)[2] |
| Typical priceUSD/kg | Not documented | 1 kg-equivalent spools cluster near 115[4][5][6] |
| Price range across brandsUSD/kg | Not documented | 110–122 at 1 kg-equivalent; Recreus 70A 110 and 60A 116 at 500 g, NinjaTek Edge 83A 112, NinjaTek Chinchilla 75A 122; the Recreus 3 kg spools fall to 70–73[4][6][5] |
| Market availability1–5 | Special order, 1–2 makers worldwide — no unfilled PA66 filament appeared in any catalogue searched, and the 3DXTech nylon range offers PA6, PA12 and a 6/66 copolymer but no straight PA66[7][8] | Niche, a handful of specialist brands[2][9][4] |
| Spool sizes & diameters | Not documented | 1.75, 2.85 and 3 mm; 0.5, 0.85, 1, 2 and 3 kg spools[2][4][10][5] |
| Typical applications | Not documented | Highly compliant seals, soft grips and prosthetic liners[2] |
| Printing Parameters | ||
| Bed temperature°C | Not documented | 50–70 (Fiberlogy FiberFlex 30D)[2] |
| Enclosure / chamber requirement1–5 | Enclosure required (passive)[1] | Open frame is fine[2] |
| Bed surface & adhesion aid | Not documented | PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent[11][12] |
| Overall printing difficulty1–5 | Advanced — enclosure, hardware upgrades, tuning[1] | Expert / industrial hardware only — below 85 Shore A the filament buckles in almost any feed path that is not a short, constrained direct drive[10][12] |
| Extruder requirement | Not documented | Direct drive only, with a constrained filament path; Bowden is not viable at this hardness[10][9] |
| Hardware Wear & Reliability | ||
| Nozzle hardness required1–4 | Not documented | Brass fine indefinitely[13] |
| Abrasiveness1–5 | Not documented | Non-abrasive[13] |
| Nozzle clog risk1–5 | Very high — frequent jams without careful setup[14][15] | High — jams from moisture, heat creep or particles; below 85 Shore A the filament buckles and compresses, and Simplify3D warns that raised feed rates most likely end in a jam[11][12][15] |
| Heat-creep / jam sensitivity1–5 | Not documented | Very high — softens in the cold zone readily[12] |
| Hotend requirement | Not documented | No special hot-end required, but a direct-drive extruder is (Simplify3D)[11] |
| Moisture Behaviour | ||
| Moisture absorption (hygroscopicity)1–5 | Very high (>2 %)[15] | Moderate[15] |
| Equilibrium moisture content at ~50 % RH% | 8.5 at saturation on extruded PA66 stock (ASTM D570) — the highest uptake of any polymer in this dataset[3] | Not documented |
| Symptoms when wet | Not documented | Bubbling and popping at the nozzle, stringing and a rough surface[15] |
| Effect of moisture on strength | 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 %[16][14] | Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[15] |
| Storage requirement | Not documented | Sealed with desiccant; often kept in a dryer during the print[15] |
| Mechanical Properties | ||
| Tensile strength (XY)MPa | 82.7 at yield and 84.8 at break on extruded PA66 stock (ASTM D638; converted from 12,000 and 12,300 psi) — no printed figure exists because no unfilled PA66 filament was found[3] | Not documented |
| Young's modulusMPa | 2413 on extruded PA66 stock (ASTM D638; converted from 350,000 psi)[3] | Not documented |
| Elongation at break% | 50 at break on extruded PA66 stock (ASTM D638)[3] | 870 at break (Fiberlogy FiberFlex 30D, ISO 527) — the highest elongation in the dataset[2] |
| Flexural strengthMPa | 113.8 on extruded PA66 stock (ASTM D790; converted from 16,500 psi)[3] | Not documented |
| Flexural modulusMPa | 3034 on extruded PA66 stock (ASTM D790; converted from 440,000 psi)[3] | Not documented |
| Other impact data | Izod 53 J/m on extruded PA66 stock, converted from 1.0 ft-lb/in (ASTM D256)[3] | Not documented |
| Brittleness1–5 | Not documented | Very ductile — bends far before failing[2] |
| Hardness (scale-specific)Shore A / Shore D / Rockwell | Shore D 86 and Rockwell 85 (108) — the source does not name the scales on extruded PA66 stock (ASTM D2240, D785)[3] | 81 Shore A and 30 Shore D (Fiberlogy FiberFlex 30D, ISO 7619)[2] |
| Creep resistance / sustained load1–5 | Not documented | Poor — no creep test at this hardness; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[17] |
| Fatigue / repeated-flex resistance1–5 | Excellent — living hinges viable[1] | Excellent — living hinges viable[12] |
| Elasticity / flexibility1–5 | Semi-flexible[14] | Rubbery / highly elastic[2] |
| Wear resistance & friction | Wear factor 200e-10 in3*min/(ft*lb*h) on extruded PA66 stock (ASTM D3702); Ensinger lists very good slide and wear properties[3] | Tear strength 95 kN/m (Fiberlogy FiberFlex 30D, ISO 34-1)[2] |
| Thermal Properties | ||
| HDT at 0.45 MPa°C | 232 on extruded PA66 stock (ASTM D648 at 66 psi; converted from 450 °F)[3] | Not documented |
| HDT at 1.8 MPa°C | 90 on extruded PA66 stock (ASTM D648 at 264 psi; converted from 194 °F) — the gap to the 0.45 MPa figure is the widest in the dataset[3] | Not documented |
| Melting point / Vicat°C | 255 melting on extruded PA66 stock (ASTM D2133; converted from 491 °F)[3] | 170 melting (Fiberlogy FiberFlex 30D, DSC)[2] |
| Continuous service temperature°C | 85 long term and 149 short term on extruded PA66 stock (converted from 185 °F and 300 °F)[3] | Not documented |
| Thermal expansion (CTE)µm/m·K | 81.0 (extruded PA66 stock, ASTM D696; source states 4.5e-5 in/in/°F)[3] | Not documented |
| Flammability / UL 94 | UL 94 V-2 on extruded PA66 stock[3] | Not documented |
| Environment & Chemical | ||
| UV resistance1–5 | Not documented | Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[12] |
| Chemical resistance | Not documented | Withstands industrial solvents and UV exposure (Polymaker)[12] |
| Food contact | Not documented | Not food safe without specific certification (Polymaker)[12] |
| Biodegradability / compostability | Not documented | Not biodegradable[12] |
| Recyclability | Not documented | Not accepted in household plastic collection[12] |
| Electrical & ESD properties | Volume resistance 1e15 ohm-cm and dielectric constant 4 on extruded PA66 stock (ASTM D257, D150)[3] | Not documented |
| Health & Safety | ||
| Fume toxicity1–5 | Moderate — measurable VOCs and UFPs, ventilation advised[18] | Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[18] |
| VOC emission rateµg/min | Up to 180 caprolactam, the dominant VOC from nylon; total VOC reached nearly 200 µg/min, the highest of the nine filaments tested[18] | Not documented |
| Ultrafine-particle emission rateparticles/min | ≈2 × 10⁸ median — low for ultrafine particles despite the highest VOC mass of any filament tested[18] | Not documented |
| Hazardous species emitted | Caprolactam, at up to 180 µg/min from nylon filament — the largest single-VOC emission rate measured in the study[18] | Not documented |
| Ventilation / filtration requirement1–5 | Ventilated room or enclosure recommended[18] | Open a window / occasional ventilation[18] |
| Post-Processing | ||
| Sanding & machining | Not documented | Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[12] |
| Gluing & solvent welding | Not documented | Cyanoacrylate bonds TPU; no common solvent welds it[12] |
| Vapour / chemical smoothing | Not documented | No practical vapour smoothing[12] |
| Support material pairing | Not documented | Polymaker warns TPU supports are often very difficult to remove[12] |
| Solvents & Solubility | ||
| Soluble in | Dissolved at 23 °C by formic acid above ~80 %, phenol, m-cresol, 96 % sulphuric acid or hexafluoroisopropanol — laboratory reagents.[19] | DMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[20] |
| Softened or crazed by | Zinc chloride solutions stress-crack it — 10 % marginal, 37 % not resistant; alcoholic calcium chloride dissolves it.[19] | Toluene and benzene swell it up to +50 % by weight at 23 °C; esters swell it severely; ethanol and IPA soften it.[20] |
| Solvent welding & smoothing agent | None — nylon's only solvents are formic acid, phenol and HFIP, all of which degrade the part they wet.[19] | None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[20] |
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
- PA (Nylon) — material basics Polymaker Wiki · 2026-08 · doc
- FiberFlex 30D Technical Data Sheet Fiberlogy · 2026-08 · tds
- TECAMID 66 natural (PA66) — stock shape properties Ensinger · 2026-08 · tds
- Recreus product catalogue Recreus · 2026-08 · vendor
- Chinchilla product page — print guidelines, spool sizes and price NinjaTek · 2026-08 · vendor
- NinjaFlex Edge product page — durometer, print guidelines and price NinjaTek · 2026-08 · vendor
- 3DXTech product catalogue 3DXTech · 2026-08 · vendor
- Polymaker product catalogue Polymaker · 2026-08 · vendor
- Filaflex 82A product page (Shore hardness and elongation) Recreus · 2026-08 · vendor
- NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
- Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
- TPU — material basics Polymaker Wiki · 2026-08 · doc
- Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
- Moisture Conditioning — effect on printed nylon properties Polymaker Wiki · 2026-08 · doc
- Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
- PolyMide CoPA Technical Data Sheet V5.4 (dry and wet status blocks) Polymaker · 2024-11 · tds
- BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
- 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
- Ultramid Nylon Chemical Resistance guide (unmodified PA6 B27E and PA66 A27E) BASF · 2026-08 · tds
- Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds