Characterization of ethylene-propylene-diene terpolymers (EPDM) by 750 MHz on-line SEC-NMR

Chemical compositions of ethylene-propylene-(2-ethylidene-5-norbornene) terpolymers were investigated by size exclusion chromatography coupled directly to 750 MHz H-1 NMR (on-line SEC-NMR). Comparison of the chromatograms obtained by monitoring the CH2 and CH3 resonances in a terpolymer sample showed clearly that ethylene/propylene ratio depends on molar mass. The measurements were carried out with continuous flow of eluent (chloroform-d, 0.2 mL/min), Molar mass dependence of a small amount (0.6-1.1 mol%) of 2-ethylidene-5-norbornene units in a terpolymer was determined by SEC-NMR using the stop-and-flow technique.