Separation and characterization of ethylene-propylene copolymers by high-temperature gradient HPLC coupled to FTIR Spectroscopy

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 degrees 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.