The effect of polarity on elastomers in contact with steam depends on the specific type of elastomer and its chemical composition. Generally, elastomers with high polarity, such as fluorocarbon (FKM) and ethylene propylene diene monomer (EPDM), have better resistance to steam than those with low polarity, such as polyurethane (PU) and silicone (VMQ).
When elastomers come into contact with steam, they may swell, harden, soften, or even disintegrate, depending on their chemical composition and the temperature and pressure of the steam. High-polarity elastomers tend to have better resistance to steam because their polar chemical groups can interact with the polar water molecules in the steam, forming hydrogen bonds that help to stabilize the elastomer’s structure.
For example, FKM elastomers, which are highly fluorinated and have strong C-F bonds, are known for their excellent resistance to steam and high temperatures. They are commonly used in high-temperature steam applications such as steam valves, turbine seals, and other components of steam systems. Similarly, EPDM elastomers, which contain polar chemical groups such as ether and ketone groups, also have good resistance to steam and are often used in steam gaskets and seals.
On the other hand, low-polarity elastomers such as PU and VMQ may not have as good resistance to steam, especially at higher temperatures and pressures. PU elastomers may undergo chemical degradation and lose their physical properties, while VMQ elastomers may experience significant swelling and softening in contact with steam.
Overall, the polarity of an elastomer can have a significant effect on its resistance to steam, and it is important to select the appropriate elastomer for specific steam applications based on its chemical composition and performance characteristics.