Continuous fractionation of polymers in solution by thermal diffusion

The possibility of carrying out continuous fractionation of polymers by the thermodiffusion method was investigated. From the working space of a plate-type column, fractions of polymer were continuously withdrawn simultaneously with filling of the column with fresh solution from a storage vessel. After equilibrium had been established, the distributions of molecular weights of the fractions were determined by a modified Baker and Williams method. In the same apparatus, and at constant temperature and concentration, fractionation, which may be characterized by a limiting viscosity number, is dependent on the total rate of withdrawal and on the ratios of amounts of polymer withdrawn in various places on the column.