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 coolant 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) |
