Ethylene propylene rubber is a copolymer of ethylene and propylene. Therefore, it is excellent in heat resistance, aging resistance, ozone resistance, and stability, but it cannot be sulfur-added. In order to solve this problem, a small amount of a double-stranded third component is introduced into the EP main chain, and sulfur can be added to form EPDM, and the temperature is generally 50-150 ° C under zero temperature. Excellent resistance to polar solvents such as alcohols and ketones: good weather resistance and ozone resistance, excellent water resistance and chemical resistance, alcohols and ketones, high temperature steam, gas With good impermeability. Disadvantages: Not recommended for food use or exposure to aromatic hydrogen.