The Use of Permeability and Capillary Theory To Characterize the Structure of Wood and Membrane Filters
Keywords:Permeability, gas flow, membrane filters, capillaries
AbstractAir permeability and bubble point measurements were made with two sizes of Nuclepore filter membrane, six other membranes of relatively nonhomogeneous structure, and three wood specimens. Radii calculated from a plot of permeability vs. reciprocal pressure, from air flow and porosity, and from the bubble point were compared. The Nuclepore filters, typical of the uniform-parallel-circular capillary model, gave values of radii by the different methods which were in close agreement. The membranes had permeability vs. reciprocal pressure plots that were linear, indicating the absence of high and low conductances in series. The six relatively nonhomogeneous membranes gave radii that differed significantly when calculated by the different methods. The wood specimens had curvilinear plots of permeability vs. reciprocal pressure, indicating high and low conductivities in series and a more nonhomogeneous structure than any of the filters. The degree of disparity in the radii measured by the different methods can be taken as a measure of structural inhomogeneity.
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