Polyurethane (PU, AU, EU)

The millable Polyurethane rubbers are distinguished into two types; one is polyester urethane (AU), the other is polyether urethane (EU). AU type urethanes have outstanding oil, fuel and solvent resistance but can be attacked by hydrolysis, EU type urethanes are not attacked by hydrolysis and still offer a fuel and oil resistance comparable to low ACN (18~22% ACN) Nitriles or HNBRs. Any type polyurethane has excellent wear resistance, high tensile strength and high elasticity in comparison with any other elastomers.
We also can offer any type thermoplastic urethane (TPU).

As you know that polyester urethane (AU) exhibits an unique property of easily getting hydrolyzed, GMORS now no longer provides this product line.

Cure system

Standard PU compounds are peroxide-cured.

Other Common Variations

  • Polyurethane usually is applied in mechanical industry, especially in the place where material must have higher wear resistance and higher strength.
  • In some applying environment, moisture condensing will happen on the surface of rubber seal, and this will cause hydrolysis of AU so choosing EU is better. But EU does not resist oil very well, thus higher aniline point oil must be used for lubricant application.
  • Applying in hydraulic system, TPU will be better than millable Polyurethane.

General Information

ASTM D 1418 Designation
Standard Color(s)
ISO/DIN 1629 Designation
Hardness Range
60-95 Shore A
ASTM D2000 / SAE J 200 Codes
Relative Cost
Medium - High

Service Temperatures

Standard Low Temperature
-40°C / -40°F
Special Compound Low Temperature
-55C / -67°F
Standard High Temperature
80°C / 176°F
Special Compound High Temperature
100°C / 212°F

Performs Well In...

  • Aliphatic hydrocarbon
  • Mineral oil and grease
  • Silicone oil and grease
  • Ozone
  • Water up to 50°C (EU type)

Doesn’t Perform Well In...

  • Ketones
  • Alcohols
  • Esters
  • Ethers
  • Hot water and steam
  • Alkalis, amines
  • Acids
  • Glycols