Ethlyene Propylene Rubber (EPM and EPDM)
Ethylene Propylene Rubber is a copolymer consisting of ethylene and propylene. The ethylene propylene polymer is chemically inert as it contains no double bonds. The lack of double bonds in the chain protects the rubber from weathering, aging and chemical attack but it also means that the EPM cannot be vulcanised with sulphur and must be peroxide cured.
Ethylene Propylene Diene Methylene (EPDM) is a terpolymer of ethylene, propylene, and diene monomers. EPDM is like EPM however with a small amount of a third monomer diene added to the rubber compound. The amount of this monomer added to the compound is around 2-5%. The addition of diene introduces double bonds to the side chain of the polymer, making the polymer chemically reactive. EPDM can therefore be sulphur or peroxide cured.
There are over 100 grades of EP and EPDM available. The grades vary in the ratio of ethylene to propylene as well as the type and amount of the third monomer added, diene. The ratio of ethylene in the compound can affect the properties of the rubber material. For high elasticity applications, a compound with 50-60% ethylene should be chosen. Ethylene levels above 70% show the highest uncured strength.
Key Properties of EPM and EPDM:
- Excellent weather properties, ozone, and oxygen resistance
- Good chemical resistance, especially to alkalis, dilute acids, glycols, water, and steam
- High tensile strength
- High operating temperatures
- Good heat aging resistance
- Good abrasion resistance
- Good tear resistance
- Can be compounded with large amounts of filler and oil to make it very economic and easy to process
- WRAS accredited, food grades and pharmaceutical grades available
- Can be difficult to bond
- High cost compared to other rubbers
- Very poor resistance to oil and fuels
Operating Temperature Range: -45 to +125 °C, up to 150°C for peroxide cured EPDM
- Excellent weathering properties
- Excellent heat resistance
- Excellent ozone resistance
- Excellent chemical resistance
- Not suitable for exposure to petroleum-based fluids and di-ester lubricants.
- Rubber roofing
- Electrical cables
- Car Radiator Hoses
- Long life outdoor applications
- Water industry (WRAS accredited form)
- Good low temperature flexibility
- Wire and cable insulation
- Automotive seals and channelling
- Gaskets and seals for dishwashers, dryers, washing machines etc.