The Effect of Polymer Structure on EPDM Properties

Harold W. Young, DSM Copolymer

EPDM is a widely used elastomer in a number of applications, such as automotive sealings and hoses, window gaskets, roofing sheets, cable and wire. Control of the polymer structure is the key to tailoring EPDM to the various application demands. The properties of EPDM terpolymers are dependent on a number of structural parameters: the relative content of monomer units in the polymer chain, the way they are distributed in the chain, the variation in the composition of different chains, average molecular weight and molecular weight distribution. Additional structural details to be considered are the type and amount of unsaturation introduced by the third monomer, the way the third monomer is distributed (more or less randomly) along the chain, and long chain branching. All these structural parameters can be regulated via the operating conditions during polymerization and the chemical composition of the catalyst.