| Abstract: | Three types of commercial styrene–acrylonitrile copolymer were fractionated by coacervate extraction and by column-elution techniques. Both methods were studied with two different solvent–nonsolvent pairs. Glass wool was used as the support material in the column. Fractionation by the coacervate extraction method was studied with benzene–triethylene glycol as a solvent–nonsolvent system at 60°C and with dichloromethane–triethylene glycol at 25°C. Column elution was carried out with acetone–methanol as the solvent–nonsolvent system at 30°C, and with dichloromethane–methanol at 20°C. Results of excellent reproducibility were obtained by these two methods. Characterization of fractions involved determination of both the molecular weight and chemical composition. It was established that the fractionation of the samples tested was dependent upon molecular weight only. The two methods described above are compared. Each gives an efficient procedure for fractionation of styrene–acrylonitrile copolymers. |
