Ethylene Propylene Diene Monomer is normally abbreviated to EPDM and is a synthetic polymer. Rubber Sheeting described as EPDM will be a blend of polymers including a percentage of EPDM. Specification Grades of sheet rubber will contain higher levels of EPDM than commercial grades. Typically used in the manufacture of Gaskets and Seals for applications where resistance to Ozone, Ageing and UV are required.