Today's KNOWLEDGE Share : Polyimide Vs PEEK

Today's KNOWLEDGE Share

PEEK Vs Polyimide - Comparing Two of the Toughest Polymers

In the realm of high-performance polymers, PEEK (Polyether Ether Ketone) and Polyimide stand out as two exceptional materials. Both are undoubtably among the toughest polymers, exhibiting tensile and flexural strengths far higher than even their nearest competitors.

Comparing chemical structure:

PEEK is a semi-crystalline thermoplastic known for its excellent mechanical properties, chemical resistance, and high-temperature stability. Its molecular structure imparts exceptional resistance to chemicals, abrasion, and wear. 

On the other hand, Polyimide (often known by its brand names of Vespel is a high-performance polymer with a unique imide linkage in its molecular structure. This arrangement contributes to outstanding thermal stability, excellent dielectric properties, and exceptional resistance to radiation and chemicals. 

Mechanical Properties:

When it comes to mechanical properties, PEEK and polyimide both display distinct characteristics. PEEK offers a combination of high strength, stiffness, and toughness. Its tensile strength and modulus are comparable to some metals, making it a preferred choice in structural applications where mechanical integrity is crucial. PEEK's inherent toughness allows it to withstand repeated loading and impact without sacrificing performance. PEEK can also be enhanced with the addition of Glass, Carbon, and Graphite (Carbon-Graphite reinforced PEEK, also called HPV PEEK, is among the toughest polymer compounds known), which adds to PEEK’s versatility.

Polyimide, while not as stiff as PEEK, excels in maintaining its mechanical properties at elevated temperatures. Its ability to withstand prolonged exposure to high temperatures without significant degradation makes polyimide suitable for aerospace, electronics, and automotive applications.

When it comes to wear resistance, polyimide take the edge, as it exhibits a slightly lower coefficient of friction. While PEEK can be improved with the addition of PTFE, the base wear rate of polyimide is both low and constant over a range of loads.

Thermal Stability:

Thermal stability is a key consideration in many high-performance applications, and both PEEK and polyimide offer exceptional heat resistance. PEEK is known for its thermal stability up to 260°C, making it suitable for applications in aerospace, automotive, and oil and gas industries. However, polyimide surpasses PEEK in terms of thermal stability, with some formulations capable of withstanding temperatures exceeding 300°C. This makes Polyimide the material of choice in extreme temperature environments such as electronics and aerospace applications.

Chemical Resistance:

Chemical resistance is another critical factor in material selection, especially in harsh operating conditions. PEEK exhibits excellent resistance to a wide range of chemicals, including acids, bases, and hydrocarbons.

source:Poly Fluoro Ltd