Materials / Compare
Plastic PETG vs. Silicon
Compare Plastic PETG 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 | 46.2MPasourcetypical | not given (tensile used) |
| Ultimate tensile strength | 46.2MPasourcetypical, peak stress (= stress at yield) | 130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point |
| Flexural strength | 78.9MPasourcetypical | 130MPasourcemodulus of rupture |
| Elongation at break | 7.6%sourcetypical | not sourced |
| Young's modulus (stiffness) | 1.94GPasourcetypical | 131GPasourcetypical (single quoted value of an anisotropic crystal) |
| Density | 1,270kg/m³sourcetypical1.83x lighter | 2,329kg/m³sourcetypical |
| Strength to weight | 36.4kN·m/kg | 55.8kN·m/kg1.53x higher |
| Stiffness to weight | 1.53MN·m/kg | 56.2MN·m/kg36.8x higher |
| Poisson's ratio | not sourced | 0.221sourcetypical |
| Shear modulus | not sourced | 53.6GPa |
| Bulk modulus | not sourced | 78.3GPa |
| Speed of sound | 1,236m/s | 7,500m/s |
| Thermal | ||
| Thermal conductivity | 0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical | 163W/m·Ksourcetypical at 313 K (40 °C) |
| Thermal expansion | 51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical | 2.62µm/m·Ksourcetypical at 300 K |
| 100 mm part over a 50 °C swing | 255µm growth | 13.1µm growth19.5x less |
| Specific heat | 1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed) | 732J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.127mm²/s | 95.6mm²/s752x faster |
| Thermal shock resistance | not sourced | 48,095W/m |
| Melting point | not sourced | 1,412°Csourcetypical |
| Glass transition | 77.4°Csourcetypical | not sourced |
| Max service temperature | 76.2°CsourceHDT 0.455 MPa (printed specimens) | 300°Csourceproducer's maximum application temperature (optical components) |
| Values for | 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. | 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.
Plastic PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic PETG stronger than Silicon?
Silicon is stronger: its tensile strength is 130 MPa against yield strength 46.2 MPa for Plastic PETG (2.81x).
Which is lighter, Plastic PETG or Silicon?
Plastic PETG is lighter: 1,270 kg/m³ against 2,329 kg/m³ for Silicon.
Which is stiffer, Plastic PETG or Silicon?
Silicon is stiffer: Young's modulus 131 GPa against 1.94 GPa for Plastic PETG, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Plastic PETG or Silicon?
For the same stiffness or strength: Plastic PETG is lighter for a strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam.
| Part that must be | Plastic PETG | Silicon |
|---|---|---|
| Stiff rod or tie (tension) | 36.8x heavier | lighter |
| Stiff beam (bending) | 4.48x heavier | lighter |
| Stiff panel or plate | 2.22x heavier | lighter |
| Strong rod or tie | 1.53x heavier | lighter |
| Strong beam | 9% heavier | lighter |
| Strong panel or plate | lighter | 9% 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 PETG or Silicon?
Silicon conducts heat better: 163 W/m·K against 0.21 W/m·K for Plastic PETG.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 51 µm/m·K for Plastic PETG.