Oil and Chemical Resistance of Polyurethanes

Need to know which Urethane has the best oil or chemical resistance for your application? Here is a partial list of oil and chemical media to which Gallagher Corporation polyurethanes have been subjected. This data was obtained on small billets totally immersed. Always test specific compounds under your particular field conditions.

Note: This table should only be used as a guide. Other requirements for satisfactory performance must be considered — e.g., exposure time, operational temperature ranges, aeration, etc. Unless otherwise stated, all immersion test data was generated at room temperature. Elevated temperatures usually increase the fluid’s effect on the urethane. If you have a specification not listed, contact us. We have more test results on file.

Samples of both Ether and Ester polyurethanes were immersed for 7 days at 75°F (24°C) in various chemicals. Samples were then removed, dried and measured for volume swell. Ratings were assigned based on: 1 = Excellent (0-3%), 2 = Good, (4-15%), 3 = Fair (16-35%), 4 = Poor (36% and up).
There are two primary types of polyurethane – polyester, and polyether. Both are useful in a multitude of industrial applications. Both are urethane elastomers. So what’s the difference?

Polyurethane Typical Elastomer Characteristics

The term elastomer — a contraction of the words elastic and polymer. Elastomers cover a group of linear polymers that exhibit a large range of elastic deformation under load. Often, they can be stretched to several times their original size. Release the force and the part will return to its original shape. This is repeatable with similar results. Polyurethane’s elastic properties are the result of a change in the distance between adjacent atoms — bond length — when under load. Hooke’s law will generally apply such that twice the force produces twice the stretch. Remove the load and the interatomic forces return the atoms to the original position. The elastic deformation recovers in full.

Polyester

• Oil/solvent resistance
• Resistance to weak acids/basics
• Abrasion resistance
• Excellent mechanical properties
• Fungus Resistance
• Excellent Vibratory Dampening

Polyester polyurethane is not recommended for use where high humidity or water exposure is a concern. Hydrolysis is a risk which will have a negative effect on the physical properties of the polyurethane.

Polyether

• Low-temperature flexibility
• Excellent hydrolytic stability
• Food Grade Applications
• Temperature resistance
• Excellent mechanical properties
• Weather (UV) resistance

Polyether polyurethanes are recommended for applications which are expected to experience medium to high stress.