Polyacrylate

Polyacrylate (ACM) — High‑Performance Sealing Rubber

What is Polyacrylate?

Polyacrylate is a synthetic elastomer belonging to the acrylate rubber family. It is produced by copolymerising ethyl acrylate (and sometimes other acrylates) with small amounts of a halogen-containing monomer (e.g. chlorine‑bearing) to enable cross-linking, thus forming an elastic, resilient rubber network.

Also known as ACM (ASTM D1418 designation: “ACM”), polyacrylate rubber combines flexibility with robust resistance to oils, heat, and environmental degradation — making it a go-to material for seals and O‑rings in demanding applications.

Why Polyacrylate Is Used for Seals

Key Strengths

• Excellent oil and fuel resistance: Polyacrylate exhibits outstanding resistance to petroleum‑based oils, fuels, automatic transmission fluids, and Type A power‑steering fluids.
• Heat and high‑temperature performance: It remains stable under continuous exposure to hot oils, making it suitable for use where temperatures reach up to around 150 °C (≈ 300 °F).
• Resistance to ozone, sunlight and ageing: Polyacrylate resists degradation from UV light, ozone and general weathering — extending seal life, especially in outdoor or exposed environments.
• Flex‑crack resistance: Its ability to resist fatigue and cracking under repeated flexing or dynamic sealing conditions makes it reliable for long-term use.

Because of these strengths, polyacrylate is widely used for O‑rings, gaskets and other rubber sealing components — especially in automotive applications like transmissions, power steering systems, and other oil‑heavy, high-temperature zones.

Typical Performance Parameters

Here is a snapshot of typical polyacrylate properties and frequently used grades:

Typical Use Cases & Industries

Due to its combination of oil resistance, thermal stability, and durability, polyacrylate rubber is commonly used in:

• Automotive components — especially in automatic transmissions and power steering systems, where exposure to hot transmission fluid and oils is constant.
• Hydraulic and power‑train systems — for O‑rings, gaskets, and seals operating under high oil pressure and elevated temperatures.
• Industrial oil‑handling equipment — wherever mineral/oil-based lubricants and hydraulic fluids are used and robust sealing is required.

Because of these weaknesses, polyacrylate is generally avoided for sealing in water‑rich, chemical‑aggressive, or very cold environments, or where repeated compression and release cycles under harsh mechanical stress are involved.

Availability & Typical Grades Supplied

Polyacrylate seals are typically supplied in standard grades such as PA60 and PA70 — representing different hardness levels (Shore A 60 and 70 respectively) to suit varying application demands.

These grades cover a common temperature band of roughly –32 °C to +149 °C, making them suitable for many automotive and industrial sealing tasks involving hot oils and fuels.

Our Recommendation — When to Use Polyacrylate

Choose polyacrylate rubber seals when:

• The system or component involves petroleum‑based oils, transmission fluids, or power‑steering fluids, particularly at elevated temperatures.
• The sealing application is static or dynamic, but not subject to extreme cold, high water exposure, or aggressive chemicals.
• Long-term resistance to ozone, sunlight and oxidation is important — for example, in automotive engine bays, hydraulic housings, or industrial oil‑handling equipment.
• You need a cost‑effective and reliable sealing solution for oil‑heavy environments where flexibility, oil resistance, and moderate temperature stability are required.

When to Consider Other Materials Instead

If your application involves low temperatures, water exposure, steam, aggressive chemicals (acids, alcohols, glycols, chlorinated solvents, etc.), or demands exceptional mechanical resilience or chemical resistance, other elastomers — such as Nitrile, Fluoroelastomer (FKM), FFKM, or specialized compounds — may perform more reliably than polyacrylate.

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While resistance to hot air ageing is superior to Nitrile, Polyacrylate strength, compression set, water resistance properties and low temperature capabilities are inferior to many other polymers. Polyacrylates are also not generally recommended for exposure to alcohol, glycols, alkalis, brake fluids, or to chlorinated or aromatic hydrocarbons.

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	Hardness	Notes	Data Sheet
PA60	BLACK	-32°C to 149°C	60	Polyacrylate 60 shore. Outstanding resistance to petroleum fuels and oils.	PA60
PA70	BLACK	-32°C to 149°C	70	Polyacrylate 70 shore. Outstanding resistance to petroleum fuels and oils.	PA70