Thermoplastic comparison
PEI (Ultem) vs Polysulfone (PSU)
Every value below is a typical room-temperature figure with its source, test method and conditions — the same dataset that drives the calculators.
Which to choose
Both are transparent amorphous high-temperature plastics that survive repeated sterilisation. PEI (Ultem) is stronger and stiffer and good for appreciably more temperature; PSU is cheaper and notably better at resisting hot water and steam over many cycles. PSU for repeatedly autoclaved parts; PEI where strength and temperature matter most.
| Property | PEI (Ultem) | Polysulfone (PSU) | Difference |
|---|---|---|---|
| Density | 1.27 g/cm³ | 1.24 g/cm³ | PEI (Ultem) — 2% higher |
| Young's modulus E | 3.2 GPa | 2.5 GPa | PEI (Ultem) — 28% higher |
| Tensile strength | 105 MPa | 70 MPa | PEI (Ultem) — 50% higher |
| Glass transition Tg | 217 °C | 185 °C | PEI (Ultem) — 32 °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.