Materials / Compare
Plastic HDPE vs. Plastic Polypropylene
Compare Plastic HDPE vs. Plastic Polypropylene 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 | 33MPasourcetypical, tensile stress at yield ISO 527 |
| Ultimate tensile strength | not sourced | not sourced |
| Elongation at break | not sourced | not sourced |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 1.45GPasourcetypical, tensile modulus ISO 527 |
| Density | 950kg/m³sourcetypical, ISO 1183 | 900kg/m³sourcetypical, 23 °C ISO 1183-1 |
| Strength to weight | 25.3kN·m/kg | 36.7kN·m/kg45% higher |
| Stiffness to weight | 0.947MN·m/kg | 1.61MN·m/kg1.7x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Shear modulus | 0.316GPa | 0.511GPa1.62x stiffer in shear |
| Bulk modulus | 2GPa | 3.02GPa |
| Speed of sound | 973m/s | 1,269m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| 100 mm part over a 50 °C swing | 600µm growth | 450µm growth33% less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | not sourced |
| Heats up and cools (diffusivity) | 0.208mm²/s | not sourced |
| Thermal shock resistance | 56.9W/m1.99x more resistant | 28.6W/m |
| Max service temperature | not sourced | 90°CsourceHDT 0.45 MPa (ISO 75B), unannealed |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values | LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), typical ISO 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 Polypropylene?
Plastic Polypropylene is stronger: its yield strength is 33 MPa against 24 MPa for Plastic HDPE (38%).
Which is lighter, Plastic HDPE or Plastic Polypropylene?
Plastic Polypropylene is lighter: 900 kg/m³ against 950 kg/m³ for Plastic HDPE.
Which is stiffer, Plastic HDPE or Plastic Polypropylene?
Plastic Polypropylene is stiffer: Young's modulus 1.45 GPa against 0.9 GPa for Plastic HDPE, so the same part in Plastic Polypropylene deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Plastic Polypropylene?
For the same stiffness or strength: Plastic Polypropylene 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 Polypropylene |
|---|---|---|
| Stiff rod or tie (tension) | 1.7x heavier | lighter |
| Stiff beam (bending) | 34% heavier | lighter |
| Stiff panel or plate | 24% heavier | lighter |
| Strong rod or tie | 45% heavier | lighter |
| Strong beam | 31% heavier | lighter |
| Strong panel or plate | 24% 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 Polypropylene?
Plastic HDPE conducts heat better: 0.445 W/m·K against 0.195 W/m·K for Plastic Polypropylene.
Which expands less with temperature?
Plastic Polypropylene expands less: 90 µm/m·K against 120 µm/m·K for Plastic HDPE.