Separation and Characterization of Ethylene‐Propylene Copolymers by High‐Temperature Gradient HPLC Coupled to FTIR Spectroscopy

Summary: The chromatographic separation of ethylene‐propylene (EP) copolymers with regard to chemical composition was accomplished by a new technique ‐ high‐ temperature gradient HPLC. Using a mobile phase of ethylene glycol monobutylether (EGMBE) and 1,2,4–trichlorobenzene (TCB), and silica gel as the stationary phase, copolymers with different ethylene contents were separated according to their chemical compositions. Using a sample solvent of n‐decanol and a column temperature of 140 °C, chromatographic conditions were established that correspond to separation in a precipitation‐redissolution mechanism. With the aim to obtain further information on the separation process, the HPLC system was coupled to FTIR spectroscopy through a LC‐Transform interface. The FTIR data confirmed that the copolymers were separated according to the ethylene content of the eluted samples.