Materials / Compare
Plastic PEEK vs. Plastic PETG
Compare Plastic PEEK vs. Plastic PETG strength, stiffness, weight and thermal properties.
| Try it on a partA bracket to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 98MPasourcetypical, tensile yield | 46.2MPasourcetypical |
| Ultimate tensile strength | not sourced | 46.2MPasourcetypical, peak stress (= stress at yield) |
| Compressive strength | 125MPasourcetypical, 23 C | not sourced |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | 78.9MPasourcetypical |
| Elongation at break | 25%sourcetypical, at break | 7.6%sourcetypical |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 1.94GPasourcetypical |
| Density | 1,300kg/m³sourcetypical (crystalline) | 1,270kg/m³sourcetypical |
| Strength to weight | 75.4kN·m/kg2.07x higher | 36.4kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg2.02x higher | 1.53MN·m/kg |
| Poisson's ratio | 0.38sourcetypical | not sourced |
| Shear modulus | 1.45GPa | not sourced |
| Bulk modulus | 5.56GPa | not sourced |
| Speed of sound | 1,754m/s | 1,236m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical |
| 100 mm part over a 50 °C swing | 275µm growth | 255µm growth8% less |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed) |
| Heats up and cools (diffusivity) | 0.101mm²/s | 0.127mm²/s25% faster |
| Thermal shock resistance | 80.1W/m | not sourced |
| Melting point | 343°Csourcetypical, DSC | not sourced |
| Glass transition | 143°Csourceonset (midpoint 150 C) | 77.4°Csourcetypical |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | 76.2°CsourceHDT 0.455 MPa (printed specimens) |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | Ultimaker PETG, 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 v1.00, April 29, 2022. |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Plastic PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic PEEK stronger than Plastic PETG?
Plastic PEEK is stronger: its yield strength is 98 MPa against 46.2 MPa for Plastic PETG (2.12x).
Which is lighter, Plastic PEEK or Plastic PETG?
Plastic PETG is lighter: 1,270 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, Plastic PEEK or Plastic PETG?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 1.94 GPa for Plastic PETG, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Plastic PETG?
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 | Plastic PEEK | Plastic PETG |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 2.02x heavier |
| Stiff beam (bending) | lighter | 40% heavier |
| Stiff panel or plate | lighter | 24% heavier |
| Strong rod or tie | lighter | 2.07x heavier |
| Strong beam | lighter | 1.61x heavier |
| Strong panel or plate | lighter | 42% heavier |
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 conducts heat better, Plastic PEEK or Plastic PETG?
Plastic PEEK conducts heat better: 0.29 W/m·K against 0.21 W/m·K for Plastic PETG.
Which expands less with temperature?
Plastic PETG expands less: 51 µm/m·K against 55 µm/m·K for Plastic PEEK.