Thermal conductivity against densityHigher and further left: spreads more heat for its weightThermal expansion against thermal conductivityLower and further right: warps less when heated
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Ultimaker PC, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS (file v5.00), April 20, 2022.
Plastic PEEK
Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07)
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Ultimaker PC Technical Data Sheet, v5.00UltiMakerarchived copyFDM Polycarbonate · Yield strength: typicalFDM Polycarbonate · Ultimate tensile strength: typical, peak stress (= stress at yield)FDM Polycarbonate · Flexural strength: typicalFDM Polycarbonate · Elongation at break: typicalFDM Polycarbonate · Young's modulus (stiffness): typicalFDM Polycarbonate · Density: rangeFDM Polycarbonate · Glass transition: typicalFDM Polycarbonate · Max service temperature: HDT 0.455 MPa (printed specimens)
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VICTREX PEEK 450G Technical Data SheetVictrexPlastic PEEK · Yield strength: typical, tensile yieldPlastic PEEK · Compressive strength: typical, 23 CPlastic PEEK · Flexural strength: typical, flexural stress at yield, 23 CPlastic PEEK · Elongation at break: typical, at breakPlastic PEEK · Young's modulus (stiffness): typical (nominal)Plastic PEEK · Density: typical (crystalline)Plastic PEEK · Thermal conductivity: typical, average, 23 CPlastic PEEK · Thermal expansion: average of flow/cross-flow, below Tg (<143 C)Plastic PEEK · Melting point: typical, DSCPlastic PEEK · Glass transition: onset (midpoint 150 C)Plastic PEEK · Max service temperature: UL 746B RTI, mechanical strength (continuous use index)
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Engineering Polymers Part and Mold Design: Thermoplastics, A Design GuideCovestroarchived copyFDM Polycarbonate · Poisson's ratio: base material: polycarbonate family typical (Covestro Part and Mold Design guide, Table 3-1)
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VICTREX PEEK for Use in Fluid Management (2020)VictrexPlastic PEEK · Poisson's ratio: typical
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Makrolon 2405 Technical Data SheetCovestroFDM Polycarbonate · Thermal conductivity: base material: Covestro Makrolon 2405 injection-molding PC, typical, through-plane, 23 °CFDM Polycarbonate · Thermal expansion: base material: Covestro Makrolon 2405 injection-molding PC, typical, 23-55 °C, parallel
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VICTREX PEEK 450G Technical Data Sheet (2012)Victrexarchived copyPlastic PEEK · Specific heat: typical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012)
Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
FDM Polycarbonate is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Mechanical
Is FDM Polycarbonate stronger than Plastic PEEK?
Plastic PEEK is stronger: its yield strength is 98 MPa against 53.3 MPa for FDM Polycarbonate (1.84x).
Which is lighter, FDM Polycarbonate or Plastic PEEK?
FDM Polycarbonate is lighter: 1,190 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, FDM Polycarbonate or Plastic PEEK?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 2.39 GPa for FDM Polycarbonate, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, FDM Polycarbonate or Plastic PEEK?
For the same stiffness or strength: Plastic PEEK is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
Part that must be
FDM Polycarbonate
Plastic PEEK
Stiff rod or tie (tension)
1.53x heavier
lighter
Stiff beam (bending)
18% heavier
lighter
Stiff panel or plate
9% heavier
lighter
Strong rod or tie
1.68x heavier
lighter
Strong beam
37% heavier
lighter
Strong panel or plate
24% heavier
lighter
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which is more ductile, FDM Polycarbonate or Plastic PEEK?
Plastic PEEK stretches further before it breaks: 25% elongation at break against 9.2% for FDM Polycarbonate.
Thermal
Which conducts heat better, FDM Polycarbonate or Plastic PEEK?
Plastic PEEK conducts heat better: 0.29 W/m·K against 0.2 W/m·K for FDM Polycarbonate.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 65 µm/m·K for FDM Polycarbonate.