EPDM rubber (ethylene propylene diene monomer (M-class) rubber), a type of synthetic rubber, is an elastomer characterized by a wide range of applications. The M refers to its classification in ASTM standard D-1418; the M class includes rubbers having a saturated chain of the polymethylene type. Dienes currently used in the manufacture of EPDM rubbers are dicyclopentadiene (DCPD), ethylidene norbornene (ENB), and vinyl norbornene (VNB). EPDM rubber is closely related to ethylene propylene rubber: ethylene propylene rubber is a copolymer of ethylene and propylene, whereas EPDM rubber is a terpolymer of ethylene, propylene, and a diene-component.
The main properties of EPDM are its outstanding heat, ozone, and weather resistance. The resistance to polar substances and steam are also good. It has excellent electrical insulating properties. It has good resistance to ketones, ordinary diluted acids, and alkalies.
Typical properties of EPDM vulcanizates are given below. EPDM can be compounded to meet specific properties to a limit, depending first on the EPDM polymers available, then the processing and curing method(s) employed. EPDMs are available in a range of molecular weights (indicated in terms of Mooney viscosity varying levels of ethylene, third monomer, and oil content.