The Full Form of EPDM is Ethylene Propylene Diene Monomer.

EPDM rubber (ethylene propylene diene monomer rubber) is a type of synthetic rubber that is used in many applications.

EPDM is an M-Class rubber under ASTM standard D-1418; the M class comprises elastomers having a saturated chain of the polyethylene type (the M deriving from the more correct term polymethylene). EPDM is made from ethylene, propylene, and a diene comonomer that enables crosslinking via Sulfur vulcanization. The earlier relative of EPDM is EPR, ethylene propylene rubber, that contains no diene units and can only be crosslinked using radical methods such as peroxides. Dienes used in the manufacture of EPDM rubbers are ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and vinyl norbornene (VNB).

EPDM is derived from polyethylene into which 45-85 wt% of propylene have been copolymerised to reduce the formation of the typical polyethylene crystallinity. EPDM is a semi-crystalline material with ethylene-type crystal structures at higher ethylene contents, becoming essentially amorphous at ethylene contents that approach 50 wt%.