Materials / Compare
Plastic PEEK vs. Plastic Polycarbonate
Compare Plastic PEEK vs. Plastic Polycarbonate 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 yield1.51x stronger | 65MPasourcetypical, tensile yield |
| Ultimate tensile strength | not sourced | 65MPasourcetypical, stress at break |
| Compressive strength | 125MPasourcetypical, 23 C | not sourced |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | 97MPasourcetypical, flexural strength |
| Elongation at break | 25%sourcetypical, at break | 125%sourcetypical, strain at break |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 2.4GPasourcetypical |
| Density | 1,300kg/m³sourcetypical (crystalline) | 1,200kg/m³sourcetypical |
| Strength to weight | 75.4kN·m/kg39% higher | 54.2kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg1.54x higher | 2MN·m/kg |
| Poisson's ratio | 0.38sourcetypical | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) |
| Shear modulus | 1.45GPa1.67x stiffer in shear | 0.87GPa |
| Bulk modulus | 5.56GPa | 3.33GPa |
| Speed of sound | 1,754m/s | 1,414m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 0.2W/m·Ksourcetypical, through-plane, 23 C |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal |
| 100 mm part over a 50 °C swing | 275µm growth18% less | 325µm growth |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 |
| Heats up and cools (diffusivity) | 0.101mm²/s | 0.142mm²/s40% faster |
| Thermal shock resistance | 80.1W/m1.55x more resistant | 51.7W/m |
| Melting point | 343°Csourcetypical, DSC | not sourced |
| Glass transition | 143°Csourceonset (midpoint 150 C) | 144°Csourcetypical, DSC 10 C/min |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values |
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.
Questions
Is Plastic PEEK stronger than Plastic Polycarbonate?
Plastic PEEK is stronger: its yield strength is 98 MPa against 65 MPa for Plastic Polycarbonate (1.51x).
Which is lighter, Plastic PEEK or Plastic Polycarbonate?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, Plastic PEEK or Plastic Polycarbonate?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Plastic Polycarbonate?
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 Polycarbonate |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 1.54x heavier |
| Stiff beam (bending) | lighter | 19% heavier |
| Stiff panel or plate | lighter | 9% heavier |
| Strong rod or tie | lighter | 39% heavier |
| Strong beam | lighter | 21% heavier |
| Strong panel or plate | lighter | 13% 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 Polycarbonate?
Plastic PEEK conducts heat better: 0.29 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.