Materials / Compare
Plastic PEEK vs. Plastic PMMA
Compare Plastic PEEK vs. Plastic PMMA 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 | not given (tensile used) |
| Ultimate tensile strength | not sourced | 80MPasourcetypical, 23 °C |
| Compressive strength | 125MPasourcetypical, 23 C | 110MPasourcecompressive yield stress, typical |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | 115MPasourcetypical |
| Elongation at break | 25%sourcetypical, at break | 5.5%sourcetypical |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 3.3GPasourcetypical, short-term |
| Density | 1,300kg/m³sourcetypical (crystalline) | 1,190kg/m³sourcetypical |
| Strength to weight | 75.4kN·m/kg12% higher | 67.2kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg11% higher | 2.77MN·m/kg |
| Poisson's ratio | 0.38sourcetypical | 0.37sourcetypical |
| Shear modulus | 1.45GPa20% stiffer in shear | 1.2GPa |
| Bulk modulus | 5.56GPa | 4.23GPa |
| Speed of sound | 1,754m/s | 1,665m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 0.19W/m·Ksourcetypical |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 70µm/m·Ksource0-50 °C |
| 100 mm part over a 50 °C swing | 275µm growth27% less | 350µm growth |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 1,470J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.101mm²/s | 0.109mm²/s7% faster |
| Thermal shock resistance | 80.1W/m1.93x more resistant | 41.5W/m |
| Melting point | 343°Csourcetypical, DSC | not sourced |
| Glass transition | 143°Csourceonset (midpoint 150 C) | not sourced |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | 80°Csourcemax. permanent service temperature |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1) |
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 PMMA?
Plastic PEEK is stronger: its yield strength is 98 MPa against tensile strength 80 MPa for Plastic PMMA (23%).
Which is lighter, Plastic PEEK or Plastic PMMA?
Plastic PMMA is lighter: 1,190 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, Plastic PEEK or Plastic PMMA?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 3.3 GPa for Plastic PMMA, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Plastic PMMA?
For the same stiffness or strength: Plastic PEEK is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam, strong panel or plate; Plastic PMMA is lighter for a stiff panel or plate.
| Part that must be | Plastic PEEK | Plastic PMMA |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 11% heavier |
| Stiff beam (bending) | about equal | about equal |
| Stiff panel or plate | 2% heavier | lighter |
| Strong rod or tie | lighter | 12% heavier |
| Strong beam | lighter | 5% heavier |
| Strong panel or plate | lighter | 1% 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 PMMA?
Plastic PEEK conducts heat better: 0.29 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 70 µm/m·K for Plastic PMMA.