USE OF THERMAL FIELD-FLOW FRACTIONATION FOR THE FRACTIONATION OF POLYBUTADIENE IN VARIOUS ORGANIC-SOLVENTS

It is shown that thermal field flow fractionation (ThFFF) can be a val uable tool for the fractionation of polybutadiene (PB). The thermal di ffusivity of four PB standards of different molecular mass was determi ned in six organic solvents. The results indicate that for this polyme r species, the thermal diffusion coefficient varies significantly with the choice of the solvent but seems to be independent of the molecula r mass. The highest retention for a given molecular mass was found wit h toluene and ethylbenzene as solvents. With respect to the speed of s eparation of polybutadiene, the best results were obtained with toluen e. The influence of the temperature drop across the channel and the po lymer concentration on retention was also studied. The use of an evapo rative light-scattering detector made it possible to work with polymer sample concentrations as low as 0. 1 mg/ml. The unique separation pos sibilities offered by ThFFF are demonstrated with the separation of po lybutadiene, polyisoprene and polystyrene standards of the same molecu lar mass using tetrahydrofuran as solvent.