Which type of plastic is most resistant to heat?

published on 16 April 2026 Reading time : 7 minutes

A plastic that initially seems to function perfectly can suddenly deform, become softer, or lose its strength at higher temperatures. Components that previously ran without problems may start to wear, creep, or even fail. The result: downtime, extra maintenance, or unexpected costs.

Especially in industrial applications, where processes run continuously and reliability is essential, choosing the wrong material can have major consequences. And yet heat resistance is still often only taken into account afterwards, when the first problems have already appeared.

The challenge is not only finding a “strong” material, but above all choosing a plastic that retains its properties under the right conditions. Because not every plastic is designed to handle heat.

In this blog, we therefore specifically look at the question: which plastics are truly suitable for higher temperatures, and which ones are better avoided?

What does heat resistance mean in plastics?

Heat resistance goes beyond just the point at which a plastic melts. In practice, it is about a material’s ability to retain its functional properties as the temperature rises, often over a longer period and under load.

Many plastics fundamentally behave differently as soon as the temperature increases. They first become more flexible, then lose stiffness, and may eventually deform or fail structurally. This process happens gradually and is not always immediately visible, which makes it especially deceptive in technical applications.

When assessing heat resistance, several factors are therefore considered together to determine whether a plastic is suitable:

Retention of mechanical strength: A material must remain sufficiently stiff and strong to withstand forces. At higher temperatures, this strength often decreases rapidly.
Dimensional stability under load: In applications where tolerances are important, a plastic must not expand or deform. Even small deviations can already cause problems.
Resistance to deformation: Under the influence of heat and constant load, plastics can slowly deform. This process is often invisible, but can eventually lead to failure.
Stability during long-term exposure: Short-term heat is different from continuous load. Many plastics can withstand peak temperatures, but perform less well under prolonged exposure.

An important distinction here is between the melting temperature and the continuous service temperature. While the melting temperature indicates when a material physically transitions to another phase, the continuous service temperature says much more about its practical usability. This is the temperature at which a plastic retains its properties over a long period without significant degradation.

In sectors such as mechanical engineering and the food industry, this difference is essential. Components here are often continuously under load and exposed to elevated temperatures. A material that is not designed for this can eventually cause wear, deviations, or even process downtime.

Plastics that are less suitable for high temperatures

Within the Lakwijk Kunststoffen range, there are many materials that perform excellently in general applications, but are less suitable when temperature plays a major role.

Materials such as POM, HDPE, PP and PVC are widely used because of their price-quality ratio and versatility. However, their thermal limits are relatively low.

POM (Polyoxymethylene) is known for its high stiffness, wear resistance and low friction. It is widely used in gears, bearings and guides. At temperatures above approximately 100–120°C, however, its mechanical properties decrease, making the material less suitable for more thermally demanding applications.

Polyethylene (HDPE) and polypropylene (PP) have even lower temperature resistance and are mainly used where chemical resistance or flexibility is more important than heat resistance.

PA (Polyamide, such as PA6 and PA66) is also widely used in technical applications. Although PA can withstand relatively high temperatures, it is sensitive to moisture absorption. In combination with heat, this can lead to deformation and loss of dimensional stability.

PETP (Polyethylene terephthalate) offers better dimensional stability, but remains limited when temperatures rise over a longer period.

In short, the following materials are usually ruled out for high temperatures:

POM
HDPE
PP
PVC
PA (in many cases, depending on the application)
PETP

These plastics remain ideal for structural applications, but are not designed for prolonged heat exposure.

The best-performing plastics at high temperatures

When temperature plays a critical role, you arrive at the so-called high-performance plastics. These materials have been developed to retain their properties under prolonged thermal load, often in combination with mechanical load and aggressive environments.

1. PAI (Polyamide-imide)

PAI belongs to the absolute top class within engineering plastics and is used in applications where both temperature and load are extreme.

PAI stands out because of its exceptional retention of mechanical properties over a wide temperature range. Whereas many plastics quickly lose stiffness at higher temperatures, PAI remains highly stable. This makes the material particularly suitable for components under constant load.

Key properties of PAI:

Continuous service temperature up to approximately 250°C
Very high mechanical strength and stiffness, also at elevated temperatures
Excellent creep resistance
Low thermal expansion, maintaining dimensional stability
Very good friction and wear behaviour
Inherently flame-retardant

Because of this combination of properties, PAI is often used in bearings, seals and precision components in sectors including aerospace and mechanical engineering.

2. PEEK (Polyetheretherketone)

PEEK is one of the most versatile high-performance plastics and is often chosen when both thermal and mechanical performance are required.

The material combines high temperature resistance with excellent strength and wear resistance. What makes PEEK special is that these properties are also retained under prolonged load.

PEEK (polyetheretherketone) has a continuous service temperature of up to approximately 250°C, with short-term peaks above 300°C. In addition, it has low thermal expansion, which ensures high dimensional stability.

Characteristic properties of PEEK:

Very high continuous service temperature
High mechanical strength and stiffness, also under heat
Excellent chemical and hydrolysis resistance
Good wear resistance and sliding properties
Inherently flame-retardant with low smoke generation
Suitable for contact with food (EU/FDA)

PEEK is used in sectors where reliability and service life are essential, such as medical applications, the semiconductor industry and high-end mechanical engineering.

3. PTFE (Polytetrafluoroethylene)

PTFE, also known under the brand name Teflon®, is a technically high-grade fluoropolymer with a unique combination of thermal and chemical properties.

The material is known for its virtually inert behaviour and is used in environments where other plastics or metals fall short. PTFE retains its properties over a very wide temperature range and can withstand temperatures from approximately -200°C to +260°C.

What distinguishes PTFE is not only its heat resistance, but above all the combination with other properties:

Very low coefficient of friction
Non-stick surface
Excellent chemical resistance, also against aggressive acids and solvents
Good electrical insulation
Very low moisture absorption
Good UV and weather resistance

PTFE is widely used in seals, gaskets, plain bearings and components that come into contact with aggressive media. In addition, it plays an important role in the chemical industry, food industry and electrical engineering.

An important point to note is that PTFE is mechanically less strong than materials such as PEEK and PAI. The material is relatively soft and sensitive to creep under load. This makes it less suitable for load-bearing structures, but highly effective in applications where low friction, chemical inertness and temperature resistance are key.

Conclusion

For applications in which temperature plays a structural role, high-performance plastics are the logical choice. Within this category, PAI (Polyamide-imide), PEEK (Polyetheretherketone) and PTFE (Polytetrafluoroethylene) in particular offer the best performance.

PAI and PEEK combine high temperature resistance with strong mechanical properties and dimensional stability under load. PTFE stands out for its exceptionally broad temperature range and chemical inertness, but is mainly used in situations where low friction and chemical resistance are central.

The final material choice always depends on the combination of factors. Temperature is important in this respect, but must always be considered in conjunction with load, environment and service life.

Need advice?

For applications involving elevated temperatures, it is wise to look beyond datasheets alone. In practice, factors such as load, contact with chemicals and moving parts often make the difference.

A well-chosen material prevents premature wear and unexpected downtime, and contributes to a more reliable process in the long term.

Not sure which plastic is right for your application? Then it is advisable to assess this properly in advance, so you can be sure that the material not only meets the requirements in theory, but also continues to perform in practice. We are happy to help you further!