Temperature: Maximum continuous use at 80-100°C (much lower than FKM or silicone) Hydrolysis: Polyester types degrade in hot, humid conditions Compression Set: Generally poorer than conventional rubbers at elevated temperatures Acids and Bases: Poor resistance to strong chemicals

Polyurethane Elastomers (AU/EU): Bridging Rubber and Plastics

Q: Outstanding Properties

Abrasion Resistance: 3-10 times better than most rubber compounds — the best of any elastomer Tensile Strength: 25-50 MPa — approaching engineering plastics Tear Strength: Exceptional — highly resistant to cut propagation Load-Bearing Capacity: Can support loads that would permanently deform conventional rubbers Hardness Range: 10 Shore A to 75 Shore D — extraordinarily wide range Oil Resistance: Good to excellent depending on formulation

In-depth exploration of Polyurethane elastomers — outstanding wear resistance, load-bearing capacity, and the engineering science behind their unique properties.

What is Polyurethane Rubber?

Polyurethane (PU) elastomers occupy a unique position in the elastomer family, bridging the gap between conventional rubbers and engineering plastics. Designated as AU (polyester-based) or EU (polyether-based) in ASTM/ISO nomenclature, polyurethane elastomers offer a remarkable combination of high tensile strength, exceptional abrasion resistance, and outstanding load-bearing capacity that no other elastomer can match.

Chemistry and Types

Polyurethane elastomers are formed by reacting a polyol (polyester or polyether) with a diisocyanate and extending the chain with a short-chain diol or diamine. The ratio of hard segments (from the isocyanate) to soft segments (from the polyol) determines the final properties.

Polyester-based (AU)

Higher tensile strength, better abrasion resistance, and superior oil resistance. However, polyester types are susceptible to hydrolysis (degradation by water) which limits their use in humid or aqueous environments.

Polyether-based (EU)

Superior hydrolysis resistance, better low-temperature flexibility, and improved dynamic properties. Preferred for applications involving water exposure or low temperatures, but with somewhat lower mechanical strength than polyester types.

Outstanding Properties

Abrasion Resistance: 3-10 times better than most rubber compounds — the best of any elastomer
Tensile Strength: 25-50 MPa — approaching engineering plastics
Tear Strength: Exceptional — highly resistant to cut propagation
Load-Bearing Capacity: Can support loads that would permanently deform conventional rubbers
Hardness Range: 10 Shore A to 75 Shore D — extraordinarily wide range
Oil Resistance: Good to excellent depending on formulation

Limitations

Temperature: Maximum continuous use at 80-100°C (much lower than FKM or silicone)
Hydrolysis: Polyester types degrade in hot, humid conditions
Compression Set: Generally poorer than conventional rubbers at elevated temperatures
Acids and Bases: Poor resistance to strong chemicals

Applications

Seals and Gaskets

Polyurethane is the material of choice for high-pressure hydraulic seals, particularly rod seals, piston seals, and wipers in mobile hydraulic equipment. Its high extrusion resistance allows it to seal at pressures that would destroy softer rubbers.

Wear Parts

Conveyor rollers, impeller linings, screen panels, and chute linings exploit polyurethane's outstanding abrasion resistance to extend service life dramatically compared to rubber or even steel.

Wheels and Tires

Forklift tires, skateboard wheels, and industrial caster wheels benefit from polyurethane's load-bearing capacity and abrasion resistance.

Mining and Mineral Processing

Hydrocyclone liners, pipe linings, and flotation cell components use polyurethane to combat the severe abrasive wear from slurry handling.

When to Choose Polyurethane

Specify polyurethane when your application demands exceptional abrasion resistance, high load-bearing capacity, or very high pressures, AND the operating temperature stays below 80°C. If temperature exceeds this, look at NBR, FKM, or other alternatives. If water exposure is likely, prefer polyether (EU) grades over polyester (AU) grades.