The Use of Permeability and Capillary Theory To Characterize the Structure of Wood and Membrane Filters


  • J. F. Siau
  • Y. Kanagawa
  • J. A. Petty


Permeability, gas flow, membrane filters, capillaries


Air 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.


ASTM. 1970. Standard test method for pore size characteristics of membrane filters for use with aerospace fluids. ASTM F 316-70. Annual Book of ASTM Standards Part 41:684-690.nBechold, H. 1908. Durchlassigkeit von Ultrafiltern. Zeitschr. Physik Chemie 64:328-343.nBlankenhorn, P. R., D. P. Barnes, D. E. Kline, and W. K. Murphey. 1978. Porosity and pore size distribution of black cherry carbonized in an inert atmosphere. Wood Sci. 11(1):23-29.nJacobs, S. 1972. The distribution of pore diameters in graded ultrafilter membranes. Filtration and Separation. September/October:525-530.nPetty, J. A. 1970. Permeability and structure of the wood of Sitka spruce. Proc. Roy. Soc. Lond. B 175:149-166.nPetty, J. A. 1974. Laminar flow through short capillaries in conifer wood. Wood Sci. Technol. 8:275-282.nSiau, J. F. 1971. Flow in wood. Syracuse University Press: Ch. 1 and 3.nSmith D. N. R., and W. B. Banks. 1971. The mechanism of flow of gases through coniferous wood. Proc. Roy. Soc. Lond. B 177:197-223.nStamm, A. J. 1964. Wood and cellulose science. Ronald: Ch. 22.nStamm, A. J. 1966. Maximum pore diameters of film materials. For. Prod. J. 16(12):59-63.nStayton, C. L., and C. A. Hart. 1965. Determining pore-size distribution in softwoods with a mercury porosimeter. For. Prod. J. 15(10):435-440.n






Research Contributions