Thermoplastic comparison
PET vs Polylactic acid (PLA)
Every value below is a typical room-temperature figure with its source, test method and conditions — the same dataset that drives the calculators.
| Property | PET | Polylactic acid (PLA) | Difference |
|---|---|---|---|
| Density | 1.37 g/cm³ | 1.24 g/cm³ | PET — 10% higher |
| Young's modulus E | 2.9 GPa | 3.5 GPa | Polylactic acid (PLA) — 21% higher |
| Tensile strength | 60 MPa | 50 MPa | PET — 20% higher |
| Glass transition Tg | 76 °C | 58 °C | PET — 18 °C higher |
| Melting point Tm | 255 °C | 160 °C | PET — 95 °C higher |
Where these numbers come from
- Callister & Rethwisch, Materials Science and Engineering, 10th ed.
- Farah, Anderson & Langer, Adv. Drug Deliv. Rev. 107 (2016) 367–392 — comprehensive PLA property review
- MakeItFrom.com materials database — typical grade values
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.