Plastics for Extreme Temperature Applications

High-performance polymers for cryogenic and elevated temperature environments

Advances in polymer technology have extended the operating temperature range of plastic materials so that they can now perform in conditions that are colder and hotter than ever before. At Curbell, we offer a variety of high-performance plastics for extreme temperatures, including Ultem®, Radel® R, PEEK (poletheretherketone) and DuPont™ Vespel®.

High performance polymers can be engineered to have any of the following characteristics, which enhance their performance in extreme temperature environments:

  • Low or high thermal conductivity
  • Low rates of thermal expansion
  • Excellent wear properties
  • Good sealing characteristics
  • Long-term thermal stability
  • Creep resistance
  • Ability to maintain their mechanical properties at very low and very high temperatures
  • Resistance to hot water and steam

Applications for plastics in high temperature and low temperature environments include:

For more information about plastics designed for extreme temperatures—and to get suggestions from our technical experts—please contact us today. 


Plastics for Cryogenic Applications  

Plastics for cold temperature and cryogenic applicationsCryogenic biotechnology machinery, spaceflight hardware, and low temperature physics equipment are sometimes required to operate at extremely cold temperatures. 

When designing plastic components for use in cryogenic conditions, it is generally beneficial to select plastic materials that exhibit ductile behavior at low temperatures and have low rates of thermal expansion. For cold temperature applications where heat transfer is a concern, it is also important to select a plastic material with the right thermal conductivity. At Curbell, we can talk with you about the variability in the thermal conductivities of plastics at cryogenic temperatures, with some materials functioning as thermal insulators and others having relatively high thermal conductivity. 

Plastics wear at different rates (and via different mechanisms) at low temperatures—so if an application requires a plastic part to function as a bearing in cryogenic conditions, it is important to select a material that has been engineered to have low friction and good wear properties at cold temperatures.


Plastics for High Temperature Applications

Selecting a plastic material for use in a high temperature environment requires careful review of material properties data. The following are some of the specific factors to consider: 

  • Strength and modulus– Plastics will soften (lose strength and modulus) at elevated temperatures. It is important to evaluate the mechanical properties of the materials being considered at the low end and high end of operating temperature range.
  • Thermal expansion– Plastics tend to have much higher rates of thermal expansion compared with metals. The coefficient of thermal expansion should be carefully reviewed to insure that CTE mismatch between plastic parts and mating metal parts does not cause the device to malfunction due to dimensional changes.
  • Creep strain and stress relaxation– Plastics exhibit increased creep strain and stress relaxation at elevated temperatures. These factors should be considered carefully during the design process.
  • Degradation– Plastics may degrade over long periods of time in high temperature environments, especially if oxygen is present. Thermal degradation curves should be reviewed when selecting polymers for use in elevated temperature environments.

 

Plastics for Wide Operating Temperature Ranges 

Plastics for broad operating temperatures - Aircraft engineAircraft, spacecraft, and other devices must function throughout a broad operating temperature range, from very low to very high temperatures. When plastics are to be used in these conditions, designers must be careful to select materials that will function reliably throughout the required temperature range. For example, the rate of thermal expansion for some plastics such as PTFE will vary considerably depending on the temperatures involved. This complicates design when a plastic part must function in direct contact with mating metal components. Some plastics including DuPont™ Vespel® tend to have very consistent rates of thermal expansion throughout a wide temperature range, simplifying part design. Vespel® formulations with additives and fillers such as Vespel® SCP-5050 are engineered to have extremely low CTEs, close to those of industrial metals. 

In addition to thermal expansion rates, our technical experts can help you review various considerations for using plastics in wide temperature ranges. For example: 

  • At cold temperatures, plastics tend to be harder, stiffer and more brittle.
  • At elevated temperatures, plastics tend to be softer and more ductile.
  • Plastics tend to have reduced chemical resistance at elevated temperatures.
  • Plastic bearings can be particularly sensitive to wide operating temperature ranges, since plastic components will undergo changes in their dimensions, mechanical properties, and friction and wear behavior when they are heated or cooled.

Extreme temperature application? We’re ready to help. 

Our technical experts have proven experience with low temperature and high temperature applications, and can suggest appropriate materials based on your requirements. Whether you’re just starting the design phase, or you need to address an immediate need, we can help. Please contact us today to learn more. 

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Frequently Asked Questions
What material properties should be considered when selecting a plastic material for a high temperature application?

Mechanical property changes, the rate of thermal degradation, creep behavior, and the coefficient of thermal expansion are all important considerations when selecting a plastic material for use in a high temperature environment.

Will plastics degrade in high temperature conditions?

Most plastic materials will exhibit reduced strength and reduced tensile elongation (embrittlement) after long term exposure to elevated temperatures. The rate of thermal degradation will vary depending on the thermal stability of the polymer and the operating temperature (higher temperature resulting in more rapid degradation). 

Can plastics operate in cryogenic environments?

Plastic materials will generally become stronger, stiffer, and more brittle at cryogenic temperatures. However, a number of high performance plastics including PEEK and DuPont™ Vespel® are widely used as bearings, seals, and thermal insulators in cryogenic applications.

What things should be considered when selecting a plastic that must perform throughout a wide operating temperature range?

Plastics generally have higher rates of thermal expansion than metals and this can result in part misalignment when an assembly with metal and plastic parts undergoes a significant temperature change. Non-plastic additives and fillers can be used to reduce the coefficient of thermal expansion of plastic materials to mitigate CTE mismatch issues.

Will the friction and wear characteristics of a plastic material change at low temperatures and elevated temperatures?

Plastics will generally exhibit reduced friction at very cold temperatures. Additives such as PTFE and graphite that improve friction and wear behavior at room temperature may be less effective at very cold temperatures. Plastic bearing materials have an upper temperature limit that is a function of their softening behavior. Bearing applications where frictional heat generated by moving parts is combined with high ambient temperatures can be particularly challenging for plastic materials.