3D Printing Info

Filament comparison

PEI 9085 vs PLA Silk

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

PEI (ULTEM 9085) guideSilk PLA guide

2 selected · all documented properties

Open these two in the interactive comparisonMore PEI 9085 comparisonsMore PLA Silk comparisons
PEI 9085 vs PLA Silk — documented properties and sources
PropertyPEI (ULTEM 9085)HIGHTEMPSilk PLAPLA
Market snapshot
Listing priceUSD/kg; dated snapshots$309.80/kg median; $220.00–$392.00/kg across 6 dated product listings$19.49/kg median; $9.75–$24.99/kg across 15 dated product listings
Identity & Market
Base polymer / chemistryPolyetherimide, ULTEM 9085 grade — the flame-retardant PEI used for aircraft interiors[1]PLA with a gloss-forming additive package; suppliers publish the composition as polylactic acid only[2]
Densityg/cm³1.34 (ISO 1183, 3DXTech) against 1.27 specific gravity on moulded plaques (ASTM D792, Stratasys) — the two suppliers disagree[1][3]1.27 (ISO 1183)[2]
Typical priceUSD/kg1 kg-equivalent spools cluster near 298[4][5][6][7]Mainstream 1 kg spools cluster near 20[8][9][10]
Price range across brandsUSD/kg220-392 across brands and formats; 3DXTech ThermaX PEI 9085 220 at 2 kg, 3D4Makers 270 at 2 kg, Fiberlogy 298 at 500 g, Kimya 321 at 500 g, IEMAI 3D 385 at 1 kg, 3DXTech CarbonX PEI 9085+CF 392[4][5][6][7][11]10–25 across brands; CHCKX 10 in a 16-roll bundle, SUNLU 13, LANDU 18, YXPOLYER 20, Polymaker 22, Devil Design 25[12][13][14][15][16]
Market availability1–5Niche, a handful of specialist brands[4][5][6][7]Stocked by most mainstream brands[8][12][17]
Spool sizes & diameters1.75 and 2.85 mm; 250 g to 2 kg spools, plus Stratasys canisters[4][7][3]1.75 mm; 1 and 1.1 kg spools; dual- and tri-colour coextruded variants[18][19]
Typical applicationsAircraft interior parts and rail rolling stock, where the flame, smoke and toxicity rating is the requirement[1]Decorative prints where surface gloss matters more than strength[2]
Diameter tolerance± mmNot documented±0.03 (Bambu Lab)[20]
Printing Parameters
Nozzle temperature°CNot documented210–240 — 20 °C above the plain PLA window[2]
Bed temperature°C130–140 (3DXTech)[1]35–45[2]
Enclosure / chamber requirement1–5Actively heated chamber required[21][22]Open frame is fine[2][23]
Part cooling fanNot documentedFan on[2]
Bed surface & adhesion aidNot documentedCool Plate SuperTack, smooth PEI or textured PEI[2]
Warping tendency1–5Severe — heated chamber needed[21]None[2]
Bed-adhesion difficulty1–5Not documentedSticks to anything[24]
Overall printing difficulty1–5Expert / industrial hardware only[21][22]Easy — minor profile tuning; hotter nozzle and slower cap of 250 mm/s[2]
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely for unfilled grades, but brass softens near these nozzle temperatures — hardened or plated hot ends are the norm[21]Brass fine indefinitely[23]
Abrasiveness1–5Non-abrasive when unfilled[1]Non-abrasive[25][23]
Nozzle clog risk1–5Moderate — needs dry filament and a clean nozzle; 3DXTech lists no special nozzle concerns but a mandatory 120 °C pre-dry before every print[26]Very low[23]
Heat-creep / jam sensitivity1–5Not documentedModerate — good heatbreak cooling needed; PLA softens below 60 °C[27]
Hotend requirementNot documentedNo special hot-end required[24]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Not documentedModerate — 0.40 % saturated at 25 °C / 55 % RH[2]
Equilibrium moisture content at ~50 % RH%Not documented0.40 saturated at 25 °C / 55 % RH (Bambu Lab)[2]
Drying temperature & timeNot documented55 °C for 8 h in a forced-air dryer, or 65–75 °C for 12 h on an X1 heatbed[2][28]
Symptoms when wetNot documentedBubbling and popping at the nozzle, stringing, rough surface and weak layers[29]
Effect of moisture on strengthNo 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[26]Polymaker rates PLA low-sensitivity — the loss shows as poor layer adhesion and brittle layers rather than a published strength figure[29]
Storage requirementNot documentedSealed with desiccant below 20 % RH; shelf life at ambient is long[30][24]
Mechanical Properties
Tensile strength (XY)MPa63-77 at break (printed XZ, ASTM D638, Stratasys F900/F3300/Fortus 450mc, three tips and two colours); 54 (printed XY, ISO 527, 3DXTech)[3][1]33 (printed XY, ISO 527); eSun Silk broke 22 % below the 16-brand PLA mean on identical 4×4 mm bars[2][31]
Young's modulusMPa2040-2540 (printed XZ, ASTM D638, Stratasys); 2050 (printed XY, ISO 527, 3DXTech)[3][1]2130 (printed XY, ISO 527)[2]
Elongation at break%5.4-9.1 at break (printed XZ, ASTM D638, Stratasys); 1.9-4.3 in ZX; 3DXTech quotes 3 (ISO 527)[3][1]2.8 (printed XY, ISO 527) — a quarter of PLA Basic at 12.2[2][30]
Flexural strengthMPa104-116 at break (printed XZ, ASTM D790 Procedure A, Stratasys); 72-98 in ZX; 3DXTech quotes 90 (ISO 178)[3][1]75 (printed XY, ISO 178)[2]
Flexural modulusMPa2400-2550 (printed XZ, ASTM D790, Stratasys F900 T16 and T16A) against 2120-2130 in ZX; 3DXTech quotes 2170 (ISO 178)[3][1]2460 (printed XY, ISO 178)[2]
Charpy impact, notchedkJ/m²Not documented10.3 (printed XY, ISO 179, notched); unnotched 18.5[2]
Other impact dataIzod notched 88.5-140 J/m XZ against 37-80 J/m ZX; unnotched 647-2260 J/m XZ against 169-633 J/m ZX (printed, ASTM D256/D4812, Stratasys, across three printers and three tips)[3]Not documented
Layer adhesion / Z tensileMPa39-63 at break (printed ZX, ASTM D638, Stratasys); the low end is the F900 T16 baseline, the high end the F3300 N500 hot end[3]25 (printed Z, ISO 527), and flexural Z collapses to 30 against 75 in XY; eSun Silk broke at 12.3 kg where twelve of the 16 plain PLAs managed 44.6–61.5 kg[2][31][32]
Brittleness1–5Brittle — snaps with little warning[1]Brittle — snaps with little warning[2]
Hardness (scale-specific)Shore A / Shore D / RockwellRockwell M110 / R126 on extruded PEI stock (ASTM D785)[33]Not documented
Creep resistance / sustained load1–5Excellent — holds load for years. Printed ZX coupons keep 87 % of room-temperature tensile strength at 104 °C and 70 % at 132 °C (ASTM D638); extruded PEI stock is rated 170 °C long-term service[3][33]Poor — no silk-specific creep data published; plain PLA sagged from 12 to 18.7–20.3 mm over 5 days at 1.25 kg[34][35]
Fatigue / repeated-flex resistance1–5Not documentedPoor — no grade-specific S-N curve; plain printed PLA ran 38 000–49 000 cycles at 30 % of tensile strength (R = 0.2)[36][27]
Elasticity / flexibility1–5Rigid[1]Rigid[2]
Z strength as % of XY%56-86 (Stratasys ZX against XZ tensile at break, ASTM D638, across F900/F3300/Fortus 450mc and T16/T20/T40A tips); 58 on the F900 T16 baseline[3]76 by tensile, 40 by flexural (printed, Bambu Lab)[2]
Thermal Properties
HDT at 0.45 MPa°C158 (printed XY, ISO 75 at 0.45 MPa, 3DXTech) to 178 (printed XY 178.2 and ZX 178.4, ASTM D648 Method B at 66 psi, Stratasys); moulded 176.9[1][3]60 (ISO 75, 0.45 MPa)[2]
HDT at 1.8 MPa°C170-173 (printed XY 170.2 and ZX 172.6, ASTM D648 Method B at 264 psi); moulded 172.9[3]56 (ISO 75, 1.8 MPa)[2]
Glass transition (Tg)°C177 (moulded plaque, ASTM D7426 inflection point, Stratasys); 186 (DSC, 3DXTech)[3][1][37]57 (DSC)[2]
Melting point / Vicat°CNot documented158 peak melt (DSC); Vicat 66 °C[2]
Continuous service temperature°C170 long-term service on extruded PEI stock, converted from 338 °F; 200 short term[33]50 — a loaded bar begins to move at this temperature (My Tech Fun, eSun eSilk PLA)[32]
Annealing responseNot documented50–55 °C for 6–12 h[2]
Thermal expansion (CTE)µm/m·K44.9 (printed XY, -50 to 80 °C, ASTM E831), falling to 31.4 over 80-160 °C; ZX gives 44.5 over -50 to 60 °C. Black pigment raises it to 51.9[3]Not documented
Flammability / UL 94UL 94 V-0 at 1.5 mm on the base resin. Printed parts are tested to 14 CFR 25.853, BSS 7238 and 7239 and AITM 2.0007B and 3.0005 covering 60 s and 12 s vertical burn, 15 s horizontal burn, smoke density, toxic gas emission and OSU heat release[1][3]Flammable; no UL 94 rating published by the major brands[30][38]
Environment & Chemical
UV resistance1–5Good — years with some colour shift. 1000 h of QUV cycling to ASTM G154 left printed ZX coupons at 55.5 MPa yield against 56.0 unexposed, with elongation and modulus unchanged[3]Degrades within weeks outdoors[27][39]
Chemical resistanceNot documentedGood against weak acids, oils and grease; poor against strong acids and alkalis; dissolved by chloroform, THF and hot benzene[38][27]
Water / humidity resistance in service1–5Not documentedGood — insoluble in water[30]
Food contactNot documentedBase resin is food-contact grade, but printed layer grooves harbour bacteria; Prusa advises against food use[27]
Biodegradability / compostabilityNot documentedIndustrially compostable only — needs sustained 55 °C; not home compostable[40][27]
RecyclabilityNot documentedMechanically recyclable; not accepted in household plastic collection[40]
Health & Safety
Fume toxicity1–5Moderate — 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[41]Low hazard — minimal VOC and particle emission[41]
Ventilation / filtration requirement1–5Ventilated room or enclosure recommended[41]None needed in a normal room[41]
Post-Processing
Sanding & machiningNot documentedWet sanding — dry sanding heats the surface by friction and smears it[39][27]
Gluing & solvent weldingNot documentedCyanoacrylate for most joints; some grades partially dissolve and bond with acetone[27][42]
Vapour / chemical smoothingNot documentedNo practical vapour smoothing — only chloroform, hot benzene or THF, which are laboratory-only[27]
Support material pairingNot documentedSupport for PLA (Bambu Lab)[2]
Dimensional accuracy & detailNot documented55° overhangs and 30 mm bridges; gloss hides fine detail and is destroyed by sanding[2]
Solvents & Solubility
Soluble inChlorinated hydrocarbons — dichloromethane and chloroform — are solvents for polyetherimide. Laboratory reagents.[43][44]Chloroform: 10 % w/v in 2–4 h at 23 °C, every grade and morphology; THF and DMF only at 65 °C. Laboratory reagents.[45]
Softened or crazed byAcetone, MEK, benzene, toluene and butyl acetate craze or stress-crack it; alcohols, fuels and dilute acids do not.[44][43]Acetone, ethyl acetate and toluene plasticise it but dissolve <1 % even at 65 °C; submersion in acetone crazes and destroys parts.[45][46]
Solvent welding & smoothing agentDichloromethane is the only welding route, and it is a controlled carcinogen rather than a workshop material.[43][44]Chloroform vapour smooths and welds PLA at the cost of tensile strength; acetone does not smooth it at all.[47][46]

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. ThermaX PEI 9085 Technical Data Sheet v4 3DXTech · 2026-08 · tds
  2. Bambu Filament Technical Data Sheet V1.0 — PLA Silk+ Bambu Lab · 2026-08 · tds
  3. ULTEM 9085 Resin — FDM Material Data Sheet Stratasys · 2026-04 · tds
  4. 3DXTech product catalogue 3DXTech · 2026-08 · vendor
  5. Kimya PEI-9085 Natural 2.85 mm 500 g igo3d · 2026-08 · vendor
  6. Fiberlogy PEI 9085 Natural, 1.75 mm / 500 g 3DJAKE · 2026-08 · vendor
  7. 3D4Makers product catalogue 3D4Makers · 2026-08 · vendor
  8. Panchroma Silk PLA collection Polymaker Shop · 2026-08 · vendor
  9. Spectrum PLA Silk — product listing 3DJake International · 2026-08 · vendor
  10. 3DJake ecoPLA Silk Black 1.75mm 1000g 3DJake International · 2026-08 · vendor
  11. IEMAI 3D PEI 9085 3D Printing Filament — store page IEMAI 3D · 2026-08 · vendor
  12. Sunlu Silk PLA+ 1.75mm 1kg Sunlu Official Store · 2026-08 · vendor
  13. Bambu Lab PLA Silk 1.75mm 1kg 3D Universe · 2026-08 · vendor
  14. CHCKX 16 Pack Silk Dual Color PLA Filament Bundle CHCKX (Amazon US) · 2026-08 · vendor
  15. YXPOLYER Silk PLA Black&Gold product page YXPOLYER · 2026-08 · vendor
  16. LANDU Silk Tri-Color PLA Filament 1.75 mm 1 kg LANDU (Amazon US) · 2026-08 · vendor
  17. Overture Silk PLA 1.75mm Overture3D · 2026-08 · vendor
  18. eSUN PLA-Silk Magic 1.75mm eSUN Official Store · 2026-08 · vendor
  19. JAYO Silk PLA+ 1.75mm 1.1kg JAYO Official Store · 2026-08 · vendor
  20. PLA Basic — product page Bambu Lab US Store · 2026-08 · vendor
  21. Prusament PEI 1010 Technical Datasheet v1.0 Prusa Polymers · 2024-09 · tds
  22. Prusament PEI 1010 — material page Prusa Polymers · 2026-08 · doc
  23. Filament Material Guide Prusa Knowledge Base · 2026-08 · doc
  24. PLA — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  25. Prusament PLA — material page Prusa Polymers · 2026-08 · doc
  26. THERMAX PEI 9085 — product page (print recommendations) 3DXTech · 2026-08 · doc
  27. PLA — material guide Prusa Knowledge Base · 2026-08 · doc
  28. Filament Drying Recommendations Bambu Lab Wiki · 2026-08 · doc
  29. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  30. Bambu Filament Technical Data Sheet V3.0 — PLA Basic Bambu Lab · 2026-08 · tds
  31. 16 PLA brand comparison test — results spreadsheet My Tech Fun (Igor Gaspar) · 2022-10 · test
  32. Testing eSun PLA filaments: PLA-ST vs PLA+ vs Silk PLA My Tech Fun (Igor Gaspar) · 2026-08 · test
  33. TECAPEI natural (PEI) — stock shape properties Ensinger · 2026-08 · tds
  34. BambuLab PLA Basic vs PLA Tough vs PLA-CF — results spreadsheet My Tech Fun (Igor Gaspar) · 2026-08 · test
  35. PolyTerra PLA vs PLA+ — results spreadsheet My Tech Fun (Igor Gaspar) · 2026-08 · test
  36. Mechanical Properties of Additively Manufactured Polymeric Materials — PLA and PETG — For Biomechanical Applications Polymers 16(13):1868 · 2024-06 · paper
  37. ThermaX PEI 1010 Technical Data Sheet v4 3DXTech · 2026-08 · tds
  38. PolyLite PLA Technical Data Sheet V5.4 Polymaker · 2024-11 · tds
  39. Prusament PLA Technical Data Sheet v1.0 Prusa Polymers · 2018-09 · tds
  40. Filamentive PLA (recycled) — product page Filamentive · 2026-08 · vendor
  41. 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
  42. Prusament rPLA Corn Pigment 1kg — product page Prusa Research · 2026-08 · vendor
  43. Radel PPSU, Veradel PESU, Acudel modified PPSU Design Guide — environmental stress cracking tables Solvay Specialty Polymers · 2026-08 · tds
  44. Chemical resistance — resistance of Ensinger plastics to chemicals (DIN 50 014, 23/50) Ensinger · 2026-08 · tds
  45. Solubility Study of Ingeo Biopolymer Grades in Common Organic Solvents (NWPD003) NatureWorks · 2019-10 · tds
  46. Improve your 3D prints with chemical smoothing Prusa Research · 2026-08 · doc
  47. Effect of vapour smoothing in trichloromethane on 3D printed PLA — surface, mechanical and chemical structure Pitale, Keche & Chopra, Engineering Research Express 6(4) 045579 · 2024-12 · paper