One must differentiate between polyester
urethane (AU) and polyether urethane (EU). AU type urethanes
exhibit better resistance to hydraulic fluids. Polyurethane
elas¬tomers, as a class, have excellent wear resistance,
high tensile strength and high elasticity in comparison with
any other elastomers. Permeability is good and comparable
with butyl.
Heat resistance
• Up to approximately 82°C (180°F).
Cold flexibility
• Down to approximately -40°C (-40°F).
Chemical resistance
• Pure aliphatic hydrocarbons (propane, butane, fuel)
• Mineral oil and grease.
• Silicone oil and grease.
• Water up to 50°C (125°F) (EU type).
• Ozone and aging resistant.
Not compatible with:
• Ketones, esters, ethers, alcohols, glycols.
• Hot water, steam, alkalis, amines, acids.
Heat resistance
• Up to approximately 204°C (400°F) (special
com¬pounds up to 232°C (450°F).
Cold flexibility
• Down to approximately -59°C to -54°C (-75°F
to -65°F) with special compounds down to -115°C (-175°F).
Chemical resistance
• Engine and transmission oil (e.g.: ASTM oil No.1).
• Animal and vegetable oil and grease.
• Brake fluid (non-petroleum base).
• Fire-resistant hydraulic fluid, HFD-R and HFD-S.
• High molecular weight chlorinated aromatic hydro¬carbons
(including flame-resistant insulators, and cool¬ant for
transformers).
• Moderate water resistance.
• Diluted salt solutions.
• Ozone, aging and weather resistant.
Not compatible with:
• Superheated water steam over 121 °C (250°F).
• Acids and alkalis.
• Low molecular weight chlorinated hydrocarbons (trichloroethylene).
• Aromatic mineral oil.
• Hydrocarbon based fuels.
• Aromatic hydrocarbons (benzene, toluene).
|
