Key Differences Between PEEK and PEKK in High-Performance Polymers
PEEK and PEKK: How do you know which plastics are best for high-performance uses and harsh environments? PEEK (Polyetheretherketone) and PEKK (Polyetherketoneketone) are two names that are frequently used in the field of recently developed materials. These advanced polymers are from the PAEK family (Polyaryletherketones), which is known for having great temperature stability, mechanical strength, and resistance.
Even though PEEK and PEKK have some things in common, their unique qualities make them useful in different fields. This blog will provide information about their chemical structures, thermal and mechanical properties, chemical resistance, processability, industry uses, and prices to help you choose the best material for your needs.
What Are PEEK and PEKK?
Polyetheretherketone, or PEEK, is a semicrystalline high-performance thermoplastic polymer known for being strong, chemically resistant, and stable at high temperatures. It is widely used in the aerospace, automotive, medical, and electronics industries.
PEEK and PEKK are both examples of high-performance thermoplastic polymers. PEKK has a structure similar to PEEK, but it has more ketone groups in its molecular structure. These extra ketone groups improve some qualities, like chemical resistance and thermal stability. Although PEEK is more commonly used, PEKK is becoming more famous because it works better in some industrial settings.
Key Differences Between PEEK and PEKK
When evaluating high-performance polymers like PEEK and PEKK, it’s important to consider various factors such as chemical structure, thermal properties, mechanical strength, and processability. Below is a quick comparison of the two materials based on key characteristics.
Differences in Chemical Structure
The main difference between PEEK and PEKK is how their chemicals are structured. Neither is unique; both are in the PAEK family and have a backbone structure with paired ether (–O–) and ketone (–C=O–) groups. Different from PEEK, PEKK has extra ketone groups that change some ether groups. In PEEK, the ether groups switch places with other ether groups.
Because of this change in structure, PEKK has its own unique properties, such as better thermal stability and sometimes higher strength. For PEKK, having more ketone groups makes it stiffer and better able to handle thermal breakdown, especially at higher temperatures.
Thermal Properties
Highly thermally stable materials, both PEEK and PEKK, but PEKK is usually better for uses that need a higher resistance to heat. It takes about 343°C for PEEK to melt, which is higher than a lot of other polymers. However, PEKK has a slightly higher melting point, usually around 350°C. PEKK can be used in places with higher temperatures because of this small benefit.
Also, PEKK is better than PEEK when it comes to long-term heat exposure because it doesn’t oxidize or break down at high temperatures. Because of this, businesses that need to be able to handle high temperatures, like aerospace or chemical processing, may choose PEKK in some cases.
Mechanical Properties
PEEK and PEKK are both powerful, stiff, and stable in terms of their dimensions. As a result, PEKK is often better for industrial applications than PEEK because it is more rigid. The extra ketone groups in PEKK make the polymer structure tougher, which makes it better at carrying weight, especially at high temperatures.
Although PEEK is known for being tough and flexible, it is best used in situations where both strength and flexibility are needed. One example of a popular use for PEEK is in medical implants, which need to be strong, durable, and flexible.
Chemical Strength
As both PEEK and PEKK are not easily damaged by chemicals, they can be used in tough conditions. They are resistant to different chemicals, though.
There are many acids, bases, and chemical solvents that PEEK does not react effectively with. It is particularly favored for use in industries such as oil and gas, where exposure to aggressive chemicals is every day.
The extra ketone groups in PEKK make it more resistant to chemicals, especially oxidizing agents. This means it can be used in situations where it will be exposed to these chemicals often. Although PEKK is more effective in harsh environments like the chemical industry, it is better at withstanding chemicals, especially when it is hot.
Processability
Due to their high melting points and the need for special tools, both PEEK and PEKK are hard to work with. A lot of people think that PEKK is easier to work with than PEEK, though. Because PEKK has more crystals, it is easier to shape and extrude, which makes the process simpler and affordable.
Due to its increased viscosity and slow crystallization, PEEK is more complex to manufacture and requires more precise control.
Both materials need extruders, injection molding machines, compression molding machines, and high temperatures. They also need high-performance molds to process at high temperatures.
Cost Comparison
PEEK costs more than PEKK due to its wider range of uses and longer market history. PEEK is more expensive because of its complicated production and raw material needs.
PEKK is slightly cheaper than other polymers, but it’s great performance makes it expensive. As PEKK becomes more popular and its specialized features are in demand, the cost may drop.
Applications and Industry Examples
Many industries use PEEK and PEKK due to its excellent characteristics. Toughness, chemical resistance, and thermal stability are common uses for PEEK. The aerospace, automotive, medical, and electronics industries use it for bearings, gears, medical implants, and electrical connectors.
PEKK’s thermal stability and chemical resistance make it ideal for particular applications. Aerospace, automotive, and chemical sectors employ it more, especially in parts exposed to severe heat or strong chemicals. Its improved mechanical characteristics and heat resistance are also making it popular in high-performance composites.
Which Should You Pick?
Choosing between PEEK and PEKK depends on what your application needs.
PEEK may be appropriate for applications requiring toughness, flexibility, and a track record. For industries like medical devices that demand strength and flexibility, it works well.
If your application requires resistance to high temperatures or aggressive chemicals, PEKK could be the better choice. This is particularly relevant in the aerospace, chemical, and high-performance composites industries.
Wrapping It Up
PEEK and PEKK are high-performance polymers with excellent mechanical, thermal, and chemical capabilities. PEKK’s heat resistance and chemical stability make it a viable rival in high-performance industries where PEEK is more extensively employed. Businesses can choose a polymer based on its chemical structures, thermal qualities, and mechanical performance.