Thermoplastic comparison
PBT (polybutylene terephthalate) 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 | PBT (polybutylene terephthalate) | PET | Difference |
|---|---|---|---|
| Density | 1.31 g/cm³ | 1.37 g/cm³ | PET — 5% higher |
| Young's modulus E | 2.6 GPa | 2.9 GPa | PET — 12% higher |
| Tensile strength | 55 MPa | 60 MPa | PET — 9% higher |
| Glass transition Tg | 45 °C | 76 °C | PET — 31 °C higher |
| Melting point Tm | 225 °C | 255 °C | PET — 30 °C higher |
Where these numbers come from
- CAMPUS plastics database — typical grade datasheet values (campusplastics.com)
- 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.