Materials / Compare
Plastic PEEK vs. Silicon
Compare Plastic PEEK vs. Silicon strength, stiffness, weight and thermal properties.
| Try it on a partA sample part 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 | 130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point |
| Compressive strength | 125MPasourcetypical, 23 C | not sourced |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | 130MPasourcemodulus of rupture |
| Elongation at break | 25%sourcetypical, at break | not sourced |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 131GPasourcetypical (single quoted value of an anisotropic crystal) |
| Density | 1,300kg/m³sourcetypical (crystalline) | 2,329kg/m³sourcetypical |
| Strength to weight | 75.4kN·m/kg35% higher | 55.8kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg | 56.2MN·m/kg18.3x higher |
| Poisson's ratio | 0.38sourcetypical | 0.221sourcetypical |
| Shear modulus | 1.45GPa | 53.6GPa37x stiffer in shear |
| Bulk modulus | 5.56GPa | 78.3GPa |
| Speed of sound | 1,754m/s | 7,500m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 163W/m·Ksourcetypical at 313 K (40 °C) |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 2.62µm/m·Ksourcetypical at 300 K |
| 100 mm part over a 50 °C swing | 275µm growth | 13.1µm growth21x less |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 732J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.101mm²/s | 95.6mm²/s943x faster |
| Thermal shock resistance | 80.1W/m | 48,095W/m600x more resistant |
| Melting point | 343°Csourcetypical, DSC | 1,412°Csourcetypical |
| Glass transition | 143°Csourceonset (midpoint 150 C) | not sourced |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | 300°Csourceproducer's maximum application temperature (optical components) |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic. |
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 Silicon?
Silicon is stronger: its tensile strength is 130 MPa against yield strength 98 MPa for Plastic PEEK (33%).
Which is lighter, Plastic PEEK or Silicon?
Plastic PEEK is lighter: 1,300 kg/m³ against 2,329 kg/m³ for Silicon.
Which is stiffer, Plastic PEEK or Silicon?
Silicon is stiffer: Young's modulus 131 GPa against 4 GPa for Plastic PEEK, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Silicon?
For the same stiffness or strength: Plastic PEEK is lighter for a strong rod or tie, strong beam, strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.
| Part that must be | Plastic PEEK | Silicon |
|---|---|---|
| Stiff rod or tie (tension) | 18.3x heavier | lighter |
| Stiff beam (bending) | 3.19x heavier | lighter |
| Stiff panel or plate | 1.79x heavier | lighter |
| Strong rod or tie | lighter | 35% heavier |
| Strong beam | lighter | 48% heavier |
| Strong panel or plate | lighter | 1.56x 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 Silicon?
Silicon conducts heat better: 163 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 55 µm/m·K for Plastic PEEK.