Materials / Compare
Plastic HDPE vs. Plastic Polycarbonate
Compare Plastic HDPE 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 | 24MPasourcetypical, tensile stress at yield 23 °C, 50 mm/min ISO 527 | 65MPasourcetypical, tensile yield |
| Ultimate tensile strength | not sourced | 65MPasourcetypical, stress at break |
| Flexural strength | not sourced | 97MPasourcetypical, flexural strength |
| Elongation at break | not sourced | 125%sourcetypical, strain at break |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 2.4GPasourcetypical |
| Density | 950kg/m³sourcetypical, ISO 1183 | 1,200kg/m³sourcetypical |
| Strength to weight | 25.3kN·m/kg | 54.2kN·m/kg2.14x higher |
| Stiffness to weight | 0.947MN·m/kg | 2MN·m/kg2.11x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) |
| Shear modulus | 0.316GPa | 0.87GPa2.75x stiffer in shear |
| Bulk modulus | 2GPa | 3.33GPa |
| Speed of sound | 973m/s | 1,414m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.2W/m·Ksourcetypical, through-plane, 23 C |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal |
| 100 mm part over a 50 °C swing | 600µm growth | 325µm growth1.85x less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 |
| Heats up and cools (diffusivity) | 0.208mm²/s46% faster | 0.142mm²/s |
| Thermal shock resistance | 56.9W/m10% more resistant | 51.7W/m |
| Glass transition | not sourced | 144°Csourcetypical, DSC 10 C/min |
| Max service temperature | not sourced | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values | 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 HDPE stronger than Plastic Polycarbonate?
Plastic Polycarbonate is stronger: its yield strength is 65 MPa against 24 MPa for Plastic HDPE (2.71x).
Which is lighter, Plastic HDPE or Plastic Polycarbonate?
Plastic HDPE is lighter: 950 kg/m³ against 1,200 kg/m³ for Plastic Polycarbonate.
Which is stiffer, Plastic HDPE or Plastic Polycarbonate?
Plastic Polycarbonate is stiffer: Young's modulus 2.4 GPa against 0.9 GPa for Plastic HDPE, so the same part in Plastic Polycarbonate deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Plastic Polycarbonate?
For the same stiffness or strength: Plastic Polycarbonate 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 Polycarbonate |
|---|---|---|
| Stiff rod or tie (tension) | 2.11x heavier | lighter |
| Stiff beam (bending) | 29% heavier | lighter |
| Stiff panel or plate | 10% heavier | lighter |
| Strong rod or tie | 2.14x heavier | lighter |
| Strong beam | 1.54x heavier | lighter |
| Strong panel or plate | 30% 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 Polycarbonate?
Plastic HDPE conducts heat better: 0.445 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Plastic Polycarbonate expands less: 65 µm/m·K against 120 µm/m·K for Plastic HDPE.