What is the difference between Ultem PEI and PEEK?

Ultem (PEI, Polyetherimide) and PEEK (Polyetheretherketone) are both high-performance engineering plastics, valued for their strength, durability, and resistance to high temperatures. While they share some similarities, they also have distinct properties that make them suitable for different applications.

Chemical Structure
Ultem PEI is a thermoplastic with a rigid aromatic backbone, consisting of ether and imide groups. This structure provides high strength, stability, and resistance to chemicals. On the other hand, PEEK is also a thermoplastic with a chemical structure consisting of alternating ether and ketone groups, offering exceptional resistance to chemicals, high temperatures, and mechanical wear.

Temperature Resistance
PEEK has superior heat resistance compared to Ultem PEI. PEEK can withstand continuous temperatures up to 250°C (482°F), while Ultem PEI is rated for continuous use up to 170°C (338°F). This makes PEEK ideal for extreme temperature applications such as in aerospace or automotive engines.

Mechanical Properties
While both materials offer excellent mechanical strength, PEEK exhibits higher tensile strength, stiffness, and fatigue resistance than Ultem PEI. This makes PEEK more suitable for heavy-duty applications that involve mechanical stress.

Applications
Ultem PEI is often used in industries such as electronics, aerospace, and medical devices due to its high dimensional stability and electrical insulating properties. PEEK is primarily used in demanding environments like aerospace, automotive, and chemical processing due to its superior thermal and chemical resistance.

Conclusion
In summary, while both Ultem PEI and PEEK are high-performance polymers, PEEK excels in extreme environments, whereas Ultem PEI is a versatile material for moderate high-temperature applications.