RELAXATION OF POLYMER-CHAINS DISSOLVED IN THE LIQUID-PHASE OF MEMBRANES UNDER A PRESSURE-GRADIENT .3. HYDROGEL MEMBRANES OF POLY(VINYL ALCOHOL) AND POLY(SODIUM L-GLUTAMATE)

The dependence of the streaming potential across hydrogel membranes on time was measured. The gel membranes used were obtained by blending v arious amounts of poly(vinyl alcohol) and poly(sodium L-glutamate), wh ich have different average molecular weights per cross-linked unit. Th e streaming potential increased rapidly just after applying a pressure difference and then increased gradually up to a steady-state value. T he time dependence of the streaming potential was analyzed as the rela xation of the polymer chains dissolved in the liquid phase of the memb rane. The relaxation for all the gel membranes consisted of a single c omponent. The relaxation time was long if the gel had a large average molecular weight per cross-linked unit. The effects of cross-linking a nd the concentration of the external solution on the relaxation time a re discussed.