Materials / Compare
Plastic HDPE vs. Plastic PEEK
Compare Plastic HDPE vs. Plastic PEEK 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 | 24MPasourcetypical, tensile stress at yield 23 °C, 50 mm/min ISO 527 | 98MPasourcetypical, tensile yield |
| Ultimate tensile strength | not sourced | not sourced |
| Compressive strength | not sourced | 125MPasourcetypical, 23 C |
| Flexural strength | not sourced | 165MPasourcetypical, flexural stress at yield, 23 C |
| Elongation at break | not sourced | 25%sourcetypical, at break |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 4GPasourcetypical (nominal) |
| Density | 950kg/m³sourcetypical, ISO 1183 | 1,300kg/m³sourcetypical (crystalline) |
| Strength to weight | 25.3kN·m/kg | 75.4kN·m/kg2.98x higher |
| Stiffness to weight | 0.947MN·m/kg | 3.08MN·m/kg3.25x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.38sourcetypical |
| Shear modulus | 0.316GPa | 1.45GPa4.59x stiffer in shear |
| Bulk modulus | 2GPa | 5.56GPa |
| Speed of sound | 973m/s | 1,754m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.29W/m·Ksourcetypical, average, 23 C |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) |
| 100 mm part over a 50 °C swing | 600µm growth | 275µm growth2.18x less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) |
| Heats up and cools (diffusivity) | 0.208mm²/s2.05x faster | 0.101mm²/s |
| Thermal shock resistance | 56.9W/m | 80.1W/m41% more resistant |
| Melting point | not sourced | 343°Csourcetypical, DSC |
| Glass transition | not sourced | 143°Csourceonset (midpoint 150 C) |
| Max service temperature | not sourced | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) |
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 HDPE stronger than Plastic PEEK?
Plastic PEEK is stronger: its yield strength is 98 MPa against 24 MPa for Plastic HDPE (4.08x).
Which is lighter, Plastic HDPE or Plastic PEEK?
Plastic HDPE is lighter: 950 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, Plastic HDPE or Plastic PEEK?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 0.9 GPa for Plastic HDPE, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Plastic PEEK?
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 HDPE | Plastic PEEK |
|---|---|---|
| Stiff rod or tie (tension) | 3.25x heavier | lighter |
| Stiff beam (bending) | 1.54x heavier | lighter |
| Stiff panel or plate | 20% heavier | lighter |
| Strong rod or tie | 2.98x heavier | lighter |
| Strong beam | 1.87x heavier | lighter |
| Strong panel or plate | 48% heavier | lighter |
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 HDPE or Plastic PEEK?
Plastic HDPE conducts heat better: 0.445 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 120 µm/m·K for Plastic HDPE.