EPDM rubbers (from the English Ethylene-Propylene Diene Monomer) are a family of synthetic rubbers of group M according to the DIN/ISO 1629 and ASTM D 1418-19 classification. Group M includes elastomers that contain polymethylene-type polymer chains without unsaturations (double or triple bonds).

The mixture of reagents for the production of EPDM rubbers contains around 45÷75% ethylene. The higher the content, the higher the polymer loading possibilities, the better the mixing and extrusion. Peroxide-based vulcanization gives these polymers a higher cross-linking density compared to their amorphous analogues. Amorphous polymers also have excellent processing characteristics, which depend on their molecular structure. The dienes, which typically vary from 2.5% to 12% by weight of the compound, act as cross-links when vulcanization is carried out with sulfur and resin, while with peroxide-based vulcanizations the diene (or third monomer) acts as a coagent and provides resistance against unwanted viscosity, slip or flow phenomena during end use.

EPDM exhibits satisfactory inertness to the aggression of polar hydraulic fluids, ketones, hot and cold water and alkalis, and unsatisfactory resistance to the majority of oils of fossil origin, petrol, kerosene, aromatic and aliphatic hydrocarbons, halogenated solvents and concentrated acids.

The main properties of EPDM are its marked resistance to heat, ozone and atmospheric agents. Resistance to polar substances and vapor are also good. It also has excellent electrical insulating properties.

EPDM rubber is used in gaskets (for example, it is used in cold room doors because it is an insulator as well as in the face seals of industrial respirators in automotive spray painting departments, where silicone must be avoided). EPDM is also used in window runners, radiators, rubber hoses for gardens and household appliances, pipes, pond liners, washing machines, belts, electrical insulation, vibrators, O-rings , in the seals of metal frames, in the heat collectors of solar panels, in the UV protection and in the conical speakers of surround systems. It is also used as a means of water resistance in electrical cable joints, in roof membranes (because it does not pollute runoff water, which is vital for rainwater collection), in geomembranes, in components rubber mechanics, in plastic impact modification, in thermoplastics, in vulcanized products and in many other applications. Colored EPDM granules are mixed with polyurethane binders and brushed or sprayed onto concrete, asphalt, screens, interlocking bricks, wood, etc., to create a non-slip, soft, porous surface for areas with damp floors such as those in swimming pools and for safety flooring under playground equipment (designed to help reduce fall injuries).

However, the most common use is probably in vehicles. It is used in door, window and trunk seals, and sometimes even in windshield seals. Frequently these same seals are a source of noise due to the movement of the door against the car body and the resulting friction between the EPDM rubber and the mating surface (the painted sheet metal or car glass). This problem can be mitigated by using special coatings applied when the seal is manufactured. Such coatings can also significantly increase the strength of EPDM rubber. Some vehicle manufacturers also recommend a light application of silicone-based dielectric lubricant to the seals to reduce noise. Other uses in vehicles include rubber cooling circuit sleeves where pumps, thermostats, exhaust gas recirculation valves and coolers, heating systems, oil coolers, radiators and degassing cylinders are connected with EPDM sleeves; furthermore, the material is found in the charge air hoses on turbocharged engines that connect the cold side of the charge air cooling system (intercooler) to the fuel manifold.