Using viscometric data, the size of the supermolecular polymer aggregate of poly(/rj-phenylene-iso(70)-co-tere-(30)-phthalamtde) (abbreviated as PA) polymer in the solution of film-casting composition was determined at various temperatures with respect to polymers of different molecular weights. On the basis of the size of the aggregate so determined and the distribution of aggregates at the solution surface obtained from a statistical thermodynamic analysis, the size of pores, called aggregate pores, that originate from the space devoid of aggregates was estimated; further, on the basis of a similar analysis the size of another type of pores, called network pores, existing in each aggregate was also estimated. The sizes of the above two kinds of pores were found comparable to those obtained by analysis of experimental RO data on the basis of the surface force-pore flow model.

In this paper the method of determining the interaction forces working between macromolecular solutes and the membrane material by the liquid chromatography method and the method of specifying the average pore size and the pore size distribution of membranes by use of the transport equations based on the surface force-pore flow model are illustrated. The effects of interaction forces and pore structure on ultrafiltration membrane performance, and membrane fouling, are Illustrated with data on separations of proteins in aqueous solutions as examples.

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