Thermoplastic comparison
PEI (Ultem) vs POM (acetal)
Every value below is a typical room-temperature figure with its source, test method and conditions — the same dataset that drives the calculators.
| Property | PEI (Ultem) | POM (acetal) | Difference |
|---|---|---|---|
| Density | 1.27 g/cm³ | 1.41 g/cm³ | POM (acetal) — 11% higher |
| Young's modulus E | 3.2 GPa | 3.1 GPa | PEI (Ultem) — 3% higher |
| Tensile strength | 105 MPa | 65 MPa | PEI (Ultem) — 62% higher |
| Glass transition Tg | 217 °C | -60 °C | PEI (Ultem) — 277 °C higher |
Where these numbers come from
- CAMPUS plastics database — typical grade datasheet values (campusplastics.com)
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.