Top 5 Heat Resistant Plastic Materials –
Manufacturers often lean towards metals like nickel and iron because of their excellent heat-resistant capabilities, making them ideal for high-performance applications. However, many manufacturers opt for plastics that can replace metals and bring some extra advantages to the table. For high-temperature applications, you need plastics to withstand thermal degradation while maintaining sufficient strength and stiffness at operating temperature.
That is where heat-resistant plastics will come in handy. Here I’m talking about plastic material that can surpass 150 °C in continuous operating temperature without trading off on mechanical properties.
Choosing the right heat-resistant plastic for your desired application is not an easy task; many things should be considered before making any major decision. Today, the 5 plastics I’m going to talk about aren’t just any high temp plastic materials but are equipped with excellent attributes such as chemical resistance, corrosion resistance, and outstanding electrical and thermal insulating properties.
Below is the well-researched list of the top 5 heat resistant plastics:
- PTFE (Polytetrafluoroethylene)
- PEEK (Polyether ether ketone)
- PEI (Polyetherimide)
- PAI (Polyamide-imide)
- PBI (Polybenzimidazole)
PTFE (Polytetrafluoroethylene) –
PTFE or Polytetrafluoroethylene, known as Teflon, is a high-performance, versatile fluoropolymer made from carbon and fluorine atoms. It is known for its non-stick properties as it has the lowest coefficient of friction against any solid know to humanity. It is also heat resistant, has outstanding chemical properties, low friction, high flexural strength, adequate insulating properties in both hot and wet environments.
The uniqueness of PTFE is sated by the fact that it is almost chemically inert and is almost insoluble in most solvents, making it perfect for high-temprature applications. It also boasts one of the highest melting points in all the thermoplastics of 327 °C and a wide range of operating temperatures. In addition, its excellent thermal stability makes it stable enough to be used anywhere between -200°C and +250°C.
|Melting Temperature (°C)||320 to 340|
|Elongation at Break (%)||300-550|
|Tensile Modulus (MPa)||550|
|Surface Energy (Dynes/g)||18|
|Dynamic Coefficient of Friction||0.04|
|Dielectric strength (kV/mm)||19.7|
|Appl. Temperature (°C)||260|
Thanks to PTFE’s non-sticking and self-lubricating properties, it is a well-known non-stick cookware application. Apart from that, it has a good presence in the engineering, automotive, and medical industries. The most common PTFE applications in those industries are seats, plugs, fittings, pumps, diaphragms, impellers, Coatings for heat exchangers, valve stem seals, shaft seals, gaskets, O-rings, linings for fuel hoses, etc.
PTFE operates very well at high and low temperatures, but its mechanical properties are inferior to comparable plastics at room temperature. It has low radiation resistance, sensitivity to creep and abrasion, weak corrosion resistance, and is prone to toxic fumes.
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2. PEEK (Polyether ether ketone) –
PEEK, aka Polyether ether ketone, is a semi-crystalline, high-performance engineering thermoplastic material offering great heat resistance up to 260°C (480°F), a combination of excellent mechanical properties and resistance to chemicals, fatigue, creep, and wear. The rigid, opaque, grey polymer belongs to polyketone family of polymers (PEK, PEEK, PEEKK, PEKK, PEKEKK). Amongst them, PEEK is the most utilized and widely manufactured on a large scale.
The polymer is so strong and adaptable to severe environments that it is often used as an alternative to metals in several applications regardless of the temperature. PEEK can resist temperature up to 310°C for short periods and has a melting point of 370°C.
PEEK exhibits exceptional tensile strength, excellent creep resistance, good flexural modulus, high volume and surface resistivity, superior fatigue performance, outstanding steam or high-pressure resistance, low friction, good dimensional stability, inherent purity, and biocompatibility.
A few drawbacks of PEEK include being easily attacked by sulphuric, nitric, and chloric acids and halogens, and sodium, and low resistance to UV lights. It is also costly thus can only be used in highly demanding applications.
PEEK can be processed best in Injection molding, Extrusion, and 3D printing. However, the most significant applications of PEEK are found in industries like aerospace, electronics, and healthcare.
3. PEI (Polyetherimide) –
Polyetherimide has been specifically developed to overcomes the challenges faced by polyamides. Although its branded name ULTEM also knows it, it is one of the few commercially available amorphous thermoplastics today. Polyetherimide is, in a way, an improved version of polyamides and exhibits high-temperature resistance and excellent mechanical and electrical properties. It is also strong, flame-resistant, and boasts the highest dielectric strength among all the highg0oermance thermoplastics.
PEI has a high melting point of 220°C and a maximum continuous service temperature of 170°C. High melting point and heat resistance capabilities make it an ideal choice for making aerospace parts. Polyetherimide possesses high tensile strength and flexural modulus, along with the ability to retain mechanical properties at elevated temperatures. It also exhibits one of the best creep resistance amongst mainstream and high-performance thermoplastic and holds up well against fuels and coolants.
Some of the drawbacks of PEI include low colorability, very high cost associated with production, and low resistance from polar chlorinated solvents, acetates, aromatic hydrocarbons leading to stress cracking.
4. PAI (Polyamide-imide) –
PAI is another high-performance thermoplastic with high-temperature resistance, high thermal stability, good chemical resistance, and supreme wear properties with temperatures up to 275°C. PAI also exhibits high tensile and compressive strength. Polyamide-imide can be processed in injection and compression molding techniques.
Polyamide-imide is mostly used in wire coatings to make magnet wires. Parts will be manufactured with PAI will also show high mechanical loading capabilities. Apart from that, PAI material provides uplifted levels of toughness and rigidity. The low thermal expansion and thermal stability in PAI contribute heavily in making dimensionally stable finished parts.
5. PBI (Polybenzimidazole) –
PBI or Polybenzimidazole, aslo known as Celazole, boast the highest heat and wear resistance, strength, and mechanical stability in all thermoplastics available today. In addition, PBI fibers have no known melting point, don’t burn, and stick to other plastics. PBI has an exceptionally high glass transition temperature of 427°C and offers outstanding load carrying capabilities in extreme temperatures. It has a continuous service temperature of 398°C in inert environments.
However, not everything is full of roses and sunshine; PBI is costly and extremely difficult to manufacture. To even further increase the cost, machining this material can only be done with diamond tools. Talking from the design perspective, one more disadvantage of PBI is the notch sensitivity.
General Applications of Heat Resistant Plastics –
Heat resistant plastics are available in many forms and shapes. These plastics are used to manufacture a wide range of products for several industries. Here are some examples –
- They are used for heat and shock withstanding components in the automotive and aerospace industries.
- They are utilized to make emission proof, heat withstanding, and highly insulating in the electrical and semiconductor industry.
- They are extensively used for sterilization and hydrolysis proof components for the medical equipment industry.
- They are utilized for making radiation-resistant and emission proof components for the nuclear energy industry.
- They are aslo utilised for making various components in the chemical industry.
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1. Can PVC resist heat?
Ans. The PVC heat withstanding capability is far less than all the plastics mentioned above. It can be specified for applications at 54.4°C (130°F). Its pressure withstanding ability aslo decreases substantially at elevated temperatures.
2. How is plastic affected by heat?
Ans. If a plastic material is exposed to heat for a prolonged period, they are affected by thermal degradation. Prolonged exposure to heat will cause loss of strength and toughness, becoming more prone to cracking, breaking, and chipping.
3. Does melting plastics release toxins?
Ans. Very harmful toxins and fumes are released when plastic is burned, and research has shown that it significantly increases the chances of cancer, respiratory illnesses, and congenital disabilities.
4. Which type of plastic will liquefy when burned?
Ans. This type of attribute is seen in thermoplastics. They can be heated, cooled, and reheated without significant reduction in their properties. In addition, thermoplastics liquefy instead of burning, making them easy to process in injection molding and subsequently recycled.
5. Which solvent can dissolve plastic?
Ans. There are many types of plastic out there with many types of solvents as well. Different solvents attack different plastics. However, the most common solvent will dissolve or at least affect its surface.
The Conclusion –
That’s all I want to say about heat resistant plastic materials. Always remember to choose wisely, consult your material supplier to know what material fits you the best. Selection of the right material is an integral part of the production, without which quality of your production can suffer.
I would appreciate your comment on your reviews and thoughts in the comment box.
Have a fantastic day 🙂