PEI (Ultem®) – polyetherimide
Amber amorphous thermoplastic, stiff and flame retardant up to 170 °C
Polyetherimide is an amorphous, amber-colored thermoplastic that is stiff and inherently flame retardant. It keeps its properties up to about 170 °C, withstands repeated steam sterilization and has good dielectric strength. Being amorphous, it is less solvent resistant than PEEK and is not recommended for sliding applications.
Designations and equivalents
| System | Designation |
|---|---|
| Abbreviation (ISO 1043) | PEI |
| Trade names | TECAPEI natural (Ensinger); Duratron U1000 PEI (MCAM); ULTEM 1000 (SABIC, resin) |
Standards by product form
| Form | Standard |
|---|---|
| Rod, sheet and tube | Manufacturer's specification (SABIC Ultem 1000 or equivalent) |
| Food contact | FDA/EU compliant grades; confirm for the lot |
| Machined part to drawing | ISO 2768 tolerance or as per drawing |
Composition and filler
Nominal composition
| Component | Content |
|---|---|
| PEI (polyetherimide) | 100% (Ultem 1000) |
Mechanical properties
Typical values from the stock-shape manufacturer's catalog, 23 °C; ISO/ASTM methods as per the source
| Property | Value |
|---|---|
| Tensile strength | 127 MPa |
| Modulus of elasticity (tensile) | 3,200 MPa |
| Elongation at break | 35% |
| Compressive strength | 92 MPa |
| Hardness | Shore D 88 |
| Notched impact | 3.5 kJ/m² |
Typical physical and thermal properties
| Property | Value |
|---|---|
| Density | 1.28 g/cm³ |
| Maximum continuous service temperature | 170 °C |
| Maximum short-term temperature | 200 °C |
| Minimum service temperature | -50 °C |
| HDT (1.8 MPa) | 195 °C |
| Melting point or glass transition | 216 °C |
| Linear thermal expansion | 50 µm/m·K |
| Thermal conductivity | 0.21 W/m·K |
| Water absorption (24 h) | 0.05-0.10% |
| Water absorption (saturation) | 1.25% |
| Dielectric strength | 27 kV/mm |
| Flammability (UL 94) | V-0 |
Calculate the weight of PEI (Ultem®) – polyetherimide bar, plate or pipe →
Chemical resistance
| Medium | Resistance |
|---|---|
| Acids | Good in dilute acids |
| Bases (alkalis) | Limited (Ensinger: resistance to hot water/bases rated negative) |
| Solvents | Limited in chlorinated and some polar solvents (amorphous, prone to stress cracking) |
| Hydrocarbons and oils | Good |
| Steam and hot water | Limited under long exposure |
Stock forms and sizes
- Rod (round bar)
- Sheet (plate)
- Tube and bushing
- Film
- Raw material: rod (round bar), sheet (plate) and tube, cut to size
- Machined part to drawing or sample, in the same order as the metal parts
- Lot certificate of conformity; FDA/EU 10/2011 declaration when the grade allows
Service temperature, machining and assembly
| Item | Usual practice |
|---|---|
| Service temperature | Continuous service up to 170 °C, short peaks up to 200 °C; minimum -50 °C (unloaded; under load, limited by HDT and creep). |
| Annealing (stress relief) | Stress-relief annealing before precision machining. |
| Bonding and welding | Bonding with epoxy or cyanoacrylate; ultrasonic welding. |
| Machining | Machines well; use a compatible coolant (no chlorinated solvents). |
Typical applications
- Medical and sterilization equipment parts
- Electrical insulators and connectors
- Aircraft parts with flammability requirements
- Food equipment components
Alternatives: PEEK for chemical service and sliding; PPSU when there is impact and frequent sterilization.
Frequently asked questions
Which standards cover PEI (Ultem®)?
Rod, sheet and tube: Manufacturer's specification (SABIC Ultem 1000 or equivalent). Food contact: FDA/EU compliant grades; confirm for the lot. Machined part to drawing: ISO 2768 tolerance or as per drawing.
Up to what temperature can PEI (Ultem®) be used?
Continuous service up to 170 °C, short peaks up to 200 °C; minimum -50 °C (unloaded; under load, limited by HDT and creep).
Which materials can replace PEI (Ultem®)?
PEEK for chemical service and sliding; PPSU when there is impact and frequent sterilization.
Is PEI suitable for bearings?
It is not the best choice: amorphous PEI has high wear. For sliding at high temperature, use bearing-grade PEEK or PAI.
