Optimum method for osmotic pressure measurements with membrane-permeating solutes



Osmotic pressure experiments were conducted with PVC samples of different molecular weights dissolved in THF, using both a block osmometer and a Hewlett-Packard automatic osmometer equipped alternately with Schleicher and Schuell 07 and 08 membranes to optimize the procedure for accurate osmotic pressure measurements. It was found that, provided a flow of solvent could be maintained through the membrane and into the solution, an osmotic pressure of good accuracy was obtained even though the membrane was nominally much too coarse for the polymer analyzed.