PROPERTIES OF DILUTE-SOLUTIONS OF ETHYLENE-PROPYLENE-DIENE TERPOLYMERS IN BENZENE AND TOLUENE

Commercial samples of ethylene-propylene-diene terpolymers (EPDM) and their fractions were characterized by osmometry (number-average molecu lar weight, second virial coefficient), viscometry (intrisic viscosity ) and H-1 NMR spectrometry (mole fraction of propylene monomeric units ). The results were analyzed in terms of the two-parameter theory of p olymer solutions. Theta temperatures and polymer-solvent interaction p arameters were estimated and correlated with composition. Existence of organized structures is indicated by high values of the reduced parti al molar entropy parameter psi. The increase in psi with increasing co ntent of ethylene units is assigned to their association. The results lend support to the previous study on the Huggins viscosity coefficien t of EPDM.