With the density and viscosity results for five polymers-poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), gelatin (Ge), starch (St), and carboxymethylcellulose (CMC)-measured in aqueous solutions at different temperatures, we have computed the excess molar volumes and activities. Smaller excess molar volumes for PVA solutions are attributed to specific types of interactions, whereas for other polymers, these data are quite large, indicating dispersion-type interactions. The activity data of the polymer solutions vary widely, depending on the nature of the polymers and their intermolecular interactions. The freestanding film properties of the polymers indicate that Ge and PVA produce stable films, whereas brittle films can be obtained for PVP and St. The mechanical strength properties of PVA and CMC have been fourid to be suitable for membrane fabrication. (c) 2007 Wiley Periodicals, Inc.