Thermoplastic comparison
Polyethylene, high-density (HDPE) vs Polypropylene (PP)
Every value below is a typical room-temperature figure with its source, test method and conditions — the same dataset that drives the calculators.
| Property | Polyethylene, high-density (HDPE) | Polypropylene (PP) | Difference |
|---|---|---|---|
| Density | 0.95 g/cm³ | 0.905 g/cm³ | Polyethylene, high-density (HDPE) — 5% higher |
| Young's modulus E | 1 GPa | 1.4 GPa | Polypropylene (PP) — 40% higher |
| Tensile strength | 27 MPa | 34 MPa | Polypropylene (PP) — 26% higher |
| Glass transition Tg | -120 °C | -10 °C | Polypropylene (PP) — 110 °C higher |
| Melting point Tm | 131 °C | 165 °C | Polypropylene (PP) — 34 °C higher |
Where these numbers come from
- Callister & Rethwisch, Materials Science and Engineering, 10th ed.
Typical room-temperature values for learning and preliminary design; grades vary widely and a supplier datasheet always overrides a textbook figure. Confirm against the datasheet before design work.