EPDM roj hmab yog ternary copolymer ntawm ethylene, propylene, thiab tsis yog conjugated dienes.
Dienes muaj cov qauv tshwj xeeb, uas tsuas yog ib qho kev sib koom ua ke ntawm ob daim ntawv cog lus koom nrog cov tshuaj tiv thaiv copolymer, thaum cov nyiaj tshuav tsawg dua ob daim ntawv cog lus tseem yog qhov tsis txaus ntseeg ntawm cov saw hlau copolymer molecular rau sulfur vulcanization. Cov saw tseem ceeb ntawm EPDM roj hmab yog saturated, uas ua rau nws tiv taus tshav kub, tshav ntuj, thiab ozone. EPDM roj hmab yog qhov tseem ceeb uas tsis yog-polar, resistant rau polar daws thiab tshuaj, nrog rau cov dej tsis haum thiab zoo rwb thaiv tsev zog.