Thermoplastic comparison
Polyethylene, high-density (HDPE) vs PET
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) | PET | Difference |
|---|---|---|---|
| Density | 0.95 g/cm³ | 1.37 g/cm³ | PET — 44% higher |
| Young's modulus E | 1 GPa | 2.9 GPa | PET — 2.9× higher |
| Tensile strength | 27 MPa | 60 MPa | PET — 2.2× higher |
| Glass transition Tg | -120 °C | 76 °C | PET — 196 °C higher |
| Melting point Tm | 131 °C | 255 °C | PET — 124 °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.