What is EPDM / EP (Ethylene Propylene)?

January 5, 2017 – by Eastern Seals

Ethylene Propylene based elastomers offer excellent chemical and thermal resistance.

EPDM is one of the most widely used synthetic rubbers. It can be used in industries ranging from automotive to HVAC (heating, ventilation and air conditioning).

These materials can be compounded in a variety of ways for use in a wide range of demanding applications.

Ethylene Propylene elastomers are generally available as EP, a copolymer of ethylene and propylene, and EPDM, a terpolymer. They have similar properties and sometimes the references EP and EPDM are used interchangeably.

EP elastomer can only be Sulphur cured.

EPDM can be either Sulphur or Peroxide cured.

Sulphur cured elastomers are often considered as standard and are less expensive and easier to process. However, the product may be slightly ‘sticky’ and may exhibit ‘bloom’.

Peroxide curing gives stable carbon to carbon bonds and the compound generally performs better at high temperatures and have good resistance to heat ageing and compression set.

Sulphur cured material will often provide better tensile and tear strength.

Service Temperature Range*:

Peroxide Cure: -60°C to +150°C
Sulphur Cure: -40°C to +135°C

Typical Applications and Products:

EPDM is a versatile and relatively inexpensive material. It is often used in drinking water systems (NSF61, KTW, WRC/WRAS) due to its Chlorine and Chloramine resistance and in hydraulic and braking systems due to its excellent Glycol resistance.

Other common uses include Medical and Pharmaceutical (USP class VI) applications and Food and Dairy applications (NSF51 and USDA 3A).

EPDM is available as O-rings, sheet, gaskets, custom mouldings, solid extrusions and sponge.

Sulphur cured EPDM will be satisfactory for normal use. It is also the most economic choice.

Peroxide cured EPDM is a better choice for heavier use in applications. This material offers:
Higher Temperature Resistance.
Good Heat Ageing Resistance.
Lower Compression Set.
Improved Resistance to Chemicals & Oils.

It is unlikely to Bloom and is resistant to:
Engine coolants.
Hot water.
Organic / inorganic acids.

It has poor resistance to:
Mineral oils.

It should not be used with most petroleum and mineral oil products.

If you’re considering Ethylene Propylene for an application, please get in touch to discuss your requirements. Give us a call on +44 (0) 1670 840529 or send us an email to Eastern Seals offers a wide range of EPDM compounds including FDA, WRAS and USP Class VI grades. Please read our Ethylene Propylene Materials page and download our EPDM data sheets.

If you already know which BS EPDM O-ring you need, you can buy BS Imperial O-rings direct from our online store.

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We are the largest supplier of British Standard, Metric series O-rings and sealing solutions.

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Eastern Seals (UK) Ltd
Unit 3 Sovereign Business Park
Jubilee Industrial Estate
Ashington | Northumberland
NE63 8UG

+44 (0) 1670 840529
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