Polyurethane

Polyurethane – High‑Performance Sealing Material

Polyurethane (sometimes abbreviated “PU”) is a polymer material widely used for O‑rings, seals, gaskets and other sealing components. Compared with many conventional elastomer materials, polyurethane offers exceptional abrasion resistance and tensile strength, making it a top choice for demanding sealing applications.

Because of these properties, polyurethane seals are particularly well‑suited to high‑pressure hydraulic systems, or any situation where seals are subjected to heavy loads, wear or abrasive contamination.

Key Performance Characteristics

Here’s a breakdown of what distinguishes polyurethane seals from other materials:

• Outstanding wear and abrasion resistance — Polyurethane maintains integrity under constant friction or abrasive conditions far longer than many standard elastomers.
• High tensile strength and tear resistance — Resistant to tearing or ripping even under mechanical stress.
• Good elasticity and flexibility — PU seals can deform under load or pressure, then recover their shape, ensuring consistent sealing performance even under repeated use or dynamic conditions.
• Chemical resistance (to oils, fuels, hydraulic fluids) — Similar to materials like nitrile rubber, polyurethane can resist many petroleum‑based oils, hydrocarbon fuels and hydraulic fluids, making it suitable for oil‑heavy or fuel‑related applications.
• Resistance to ozone, UV, and ageing (to some extent) — Polyurethane can maintain performance outdoors or under exposure to sunlight, although performance depends on formulation and usage conditions.
• Low friction coefficient (in some formulations) — This helps reduce wear on both the seal and the mating surfaces, advantageous for dynamic or moving assemblies.

Overall, polyurethane offers a balanced and robust combination of durability, resilience and chemical/mechanical resistance — often outperforming common elastomers such as nitrile, natural rubber or silicone in heavy‑duty sealing tasks.

Typical Applications

Thanks to these properties, polyurethane seals and components are used across a broad array of industries and applications, including:

• Hydraulic and pneumatic systems — ideal for cylinders, valves, pumps and systems subject to high pressures, shock loading, reciprocating motion or abrasive contamination.
• Industrial machinery and plant equipment — wherever wear resistance and long seal life are crucial (e.g. manufacturing, material handling, heavy‑duty equipment).
• Automotive and heavy‑vehicle applications — engine, transmission or hydraulic sealing where oil/fuel and mechanical stress are present.
• Pumps, compressors and fluid‑handling systems — to prevent leaks of oils, fuels, hydraulic fluids or other liquids.
• Custom seals and O‑rings for bespoke projects — polyurethane’s machinability and versatility allow production of specific sizes/shapes, from prototypes to large runs.

Why Choose Polyurethane Seals — Key Benefits

When you require reliable, long‑lasting, heavy‑duty sealing, polyurethane offers:

• Outstanding durability under wear, abrasion and mechanical stress — extending seal life and reducing maintenance or replacement frequency.
• Strong chemical and oil compatibility — reducing risk of degradation when exposed to petroleum products, hydraulic fluids or lubricants.
• Flexibility and elasticity — allowing effective sealing even under dynamic movement or pressure fluctuations.
• Versatility — available in multiple hardness levels, customizable shapes and sizes, suitable for a wide array of industrial, automotive, hydraulic and fluid‑handling applications.

In short: polyurethane seals deliver a cost‑effective balance of strength, resilience and versatility, especially when longevity and reliability matter.

Important Notes & Best Practices

• Always verify the material datasheet from the supplier prior to selecting PU seals — actual properties depend on the specific compound, curing method and additives used.
• Ensure that the operating environment (temperature, chemicals, pressure, motion) is compatible with the PU grade chosen. For extreme chemical or thermal conditions, consider alternative materials or specialized PU formulations.
• When in doubt, consult with seal manufacturers or technical experts to confirm suitability for your application — especially for high‑pressure or safety‑critical systems.
• Water sensitivity depends on PU chemistry.

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Unless specially compounded, at elevated temperatures Polyurethane begins to soften, losing its physical strength and chemical resistance advantages over other polymers. Tending to rapidly deteriorate when exposed to concentrated acids, ketones, esters, chlorinated and nitro hydrocarbons, Polyurethanes are also prone to hot water and steam degradation.

Please note: This Material Data Sheet section is to be used as a professional guide only. Eastern Seals (UK) Ltd may source their products from a variety of Quality Approved Suppliers and the data shown should not be relied upon by any purchaser without verification of material source.

ES REF	Colour	Temp Range	Shore	Notes	Data Sheet
PU70	CLEAR	-50°C to +80°C	70	POLYURETHANE 70 SHORE – PEROXIDE CURED	PU70
PU90	CLEAR	-50°C to +80°C	90	POLYURETHANE 90 SHORE	PU90