Sulfur curable EP rubber: EPDM terpolymers from LANXESS

As the copolymerization results in a saturated backbone, sulfur vulcanization cannot be used to crosslink EPM since no unsaturation exists. Therefore, e.g. peroxide cure must be used. Peroxide curing of EPM is more efficient at high ethylene compositions due to competing chain scission which occurs at the tertiary carbon atoms of the propylene units.

 

To get a sulfur-curable rubber, a non-conjugated diene is introduced as a third monomer during polymerization. Appropriate third monomers contain one double bond which takes part in the polymerization and one which does not. This results in pendant unsaturation which supplies crosslinking sites without affecting the saturated main chain. In Buna® EP terpolymers from LANXESS, ethylidene norbornene (ENB) serves as the third monomer.

 

 

Buna is a registered trademark in many countries of the world.