Top 5 Heat Resistant Plastics
The use of plastics is widespread in every industry for a lot of reasons. Most of the applications look forward to having heat-resistant plastics that can be used under high temperatures.
The top 5 heat resistant plastics that you can use in your applications are discussed below.
Amorphous vs. Semi Crystalline Plastics
First, let's talk about the two categories into which plastics are divided.
Semicrystalline
Semi-crystalline plastics have a semi-ordered molecular structure, and they also have ordered crystalline areas.
Semi-crystalline plastic is a very quick transition from solid to liquid. These plastics have a melting point that is defined and used for the production of films, blends, and plastics like PP, PET, PE, etc.
Amorphous
Amorphous plastics have no crystalline areas and have a disordered molecular structure.
These plastics tend to get soft when subjected to high temperatures, and they do not have any specific melting point. PVC, PS, and PSU are amorphous plastics.
Thermal Properties of Heat-Resistant Plastics
Here, let’s discuss some properties that heat-resistant plastics are composed of.
Melting Point
The melting point is the point at which the plastics from the molecular state turn into a disordered state. Semi-crystalline plastics have a point at which such transition takes place, but amorphous ones gradually tend to get softer upon heating.
Heat Deflection Temperature
Heat deflection temperature is defined by conducting a test. In the test, a given load is applied to the given sample at a certain temperature.
The temperature is measured to see how the material can maintain its stiffness when the load is applied, and it is called heat deflection temperature.
Continuous Operating Temperature
The continuous operating temperature is the maximum safe temperature which keeps the plastic stable in the long run.
This temperature is measured as the plastic is exposed to air– as exposure to chemicals and water can reduce its continuous operating temperature.
Glass Transition Temperature
The glass transition temperature is the point at which the plastic transforms from a ductile state to a brittle one. Some plastics have values lower than zero.
The glass transition temperature is the one at which the amorphous plastic changes its state from a harder one to a rubbery one.
Flame Resistance
The flame resistance of plastics determines the resistance of plastic to flames. The flammability of plastic is rated on a scale, and it measures the way plastic performs when subjected to high temperatures.
Top 5 Heat-Resistant Plastics
The top 5 high-temperature plastic types, along with their pros and cons, are discussed below.
1. PEI
PEI is a durable thermoplastic that offers excellent resistance against flame and chemicals. It has high strength. It has a melting point of 219 centigrade. Its continuous use temperature is 170 centigrade.
It is suitable for applications in aerospace, circuit boards, and even equipment used for food sterilization.
Advantages
- It can hold up against coolants and fuels.
- It has improved creep resistance.
Disadvantages
- It can crack in the presence of polar chlorinated solvents.
- It is an expensive type of thermoplastic.
2. PEEK
PEEK is a thermoplastic that offers high performance. It has high creep, chemical, and wear resistance. It has a melting point of 371 centigrade, and it has a strength like metal.
It is used in applications that are subjected to harsh surroundings. It is mostly opted for aircraft interior components, medical parts, and automobile components. It can be machined and subjected to injection molding.
Advantages
- It can easily adapt to harsh surroundings.
- It has a high tensile strength.
- It is compatible with injection molding and CNC machining.
Disadvantages
- It is susceptible to some acids and UV rays.
3. PTFE
PTFE is also known as Teflon and is a plastic that is known for its chemical resistance. It has low friction and high resistance against heat.
The melting point of PTFE is 327 centigrade. It does not react with chemicals and offers electrical insulation. It is used in gaskets, seals, and insulator materials in electronics.
Advantages
- PTFE offers high weathering resistance.
- It has excellent electrical induction in wet as well as hot surroundings.
- The flexural strength of the PTFE is high.
Disadvantages
- It is expensive to process PTFE.
- PTFE is not resistant to radiation, creep, and abrasion
- It is inferior at room temperature.
4. PPS
Polyphenylene Sulfide is a thermoplastic with high-temperature stability and excellent mechanical strength. It is also highly resistant to chemicals and is a semi-crystalline plastic suitable for harsh surroundings.
Advantages
- PPS has high resistance against temperature and chemicals.
- It has a high dimensional stability.
- The electrical insulation properties of PPS are exceptional.
- It has high resistance against flame.
Disadvantages
- PPS has a brittle texture and may crack under stress.
- Processing PPS is challenging.
- It has limited options in colors.
5. PBI
PBI has the highest resistance against wear and heat, and it offers excellent mechanical stability. PBI doesn't have a specific melting point, and it neither burns nor sticks to other plastics. They are suitable for being machined using diamond tools, but this increases the cost of processing.
Advantages
- PBI is an excellent high heat resistant plastic.
- It has high stability.
- It doesn't have a melting point.
Disadvantages
- It is costly to manufacture
- It is highly sensitive.
Methods for Improving Heat Resistance
The methods through which the heat resistance of the thermoplastics can be increased are as follows:
Additives
Thermal stabilizers that have antioxidants are used so that the plastic’s thermal behavior is improved. The addition of fire retardant additives makes the materials resistant to flame.
Fillers
Fillers can also be added to the thermoplastics, which improve the thermal resistance of these plastics. Examples of some fillers are ceramic powder and glass fiber strands.
Applications of Heat-Resistant Plastics
Heat-resistant plastics are used in many applications due to their high resistance against heat and chemicals and also the lightweight they possess. Some of the applications of heat resistant plastics are as follows:
- Pumps and valves
- Instruments used in medical and laboratory applications
- Mechanical components
- Components for food machinery
Conclusion
The requirements of the application determine the type of plastic a component will be made of. It is crucial to opt for a heat resistant plastic when the components are subjected to high heat.
DEK offers to manufacture components using a wide range of plastics, and these components have exceptional quality.
