Studies on the Permeation Mechanism of Polymer Solutions through Fiber Bed

The mechanism of the permeation of polymer solutions, used for Japanese paper making, through vinylon fiber bed was studied. The polymers used were Tororo-aoi mucilage (TA), sodium polyacrylate (NaPAA, M. W.3.56 X 10°) and polyethylene oxide (PEO, M. W.0.46, 3.54 X 10°). The change of permeation rate caused by alternation in the porosity of fiber bed was characterized by the varieties of the polymer solution. The permeability coefficients calculated from the permeation rates of TA and of higher molecular weight PEO were significantly smaller than that calculated from water. As for TA, the results were appreciably explained in terms of a pore radius decrease in the bed which was due to the thicker immobile layer caused by the polymer adsorption on fiber surface. On the other hand, as for PEO, it was suggested that the decrease in permeability coefficients should depend not only on the adsorbed layer, but also on the viscoelastic properties of the polymer solution. In the case of NaPAA, such an immobile layer as governing the permeability was absent.