Plastics for cryogenic and high temperature applications

Because polymer technology has experienced a major evolution, plastic materials have the ability to resist and perform in extreme conditions in relation to the temperature. All the high temperature polymers must include specific characteristics in order to lift up to the manufacturers’ requirements and standards. These characteristics have the goal to control the behavior of plastics in environments that present hotter and colder temperatures than ever anticipated and include creep resistance, exceptional wear properties, excellent resistance to hot water, thermal stability, high and low thermal conductivity, good sealing traits.

Characteristics of plastics at extreme temperatures

Plastics that present high resistance to extreme temperatures are very useful for various applications that demand superior mechanical properties and involve speeds or loads. If the plastic encounters moving parts, it must prove to wear resistance and low friction while withstanding various chemicals. The creep resistance represents a trait that helps to maintain tight seals while low stiffness is essential for mating surfaces. Moreover, plastics are perfect for electrical insulation. The multitude of polymers available provides irreproachable fire resistance and dielectric strength. Of course, manufacturers have performed multiple tests in order to meet the highest electrical standards. Because plastics offer low thermal conductivity at extremely cold temperatures, they can be used as part of physics research equipment.

Material selection for high temperatures application

Considering that the high temperature poyurethane will be used in high temperatures environments, manufacturers must analyze data concerning the material properties. The main factors they always keep in mind are degradation, thermal expansion, strength and modulus, stress relaxation and creep. Manufacturers must assess and control thermal degradation of polymers, which might degrade after a long period when facing high temperature environments. In comparison with metals, plastics materials are more vulnerable when it comes to thermal expansion meaning that they change in the area, volume and shape in response to drastic temperature change. That being said, manufacturers must ensure that dimensional changes between metal parts and plastic parts do not lead to a malfunction. When exposed to extremely hot temperatures, plastic material become soft, this means that they lose strength and modulus. For this reason, the importance of examining mechanical properties cannot be neglected. Apart from losing strength and modulus at high temperatures, plastics present higher stress relaxation and creep strain, factors that need to be taken into account during the production process.

Material selection for cryogenic applications

Plastic materials are also exposed to cryogenic temperatures, not only in extremely hot environments. When producing plastic components for this type of situation, manufacturers ensure that the plastics present a low thermal expansion and ductile behavior. The adequate thermal conductivity is imperative when dealing with heat transfer. Plastics wear differently when in cold environments so if they must be produced for bearing, choosing a material with low friction and excellent wear properties at cryogenic temperatures becomes essential. In certain industries including aircraft and spacecraft, the temperature level varies. This means that plastics must function perfectly throughout the respective temperature range. Obviously, various considerations appear when using plastics at different temperatures.