Powder Technology, Vol.320, 295-303, 2017
Characterization of the porous structure of a non-woven fibrous medium for air filtration at local and global scales using porosimetry and X-ray micro-tomography
The present study focuses on complementary experimental methods to characterize the structural properties of a high performance composite medium made of a polymer membrane laminated to a fibrous support, and used for air filtration, at global and local scales. This two-scale approach aims to evaluate the in-plane homogeneity of the properties of the two layers of the medium. The structure of the medium is observed in 2D by Scanning Electron Microscopy, and in 3D by X-ray micro tomography. Those observations enable for example the isotropic/anisotropic nature of each layer of the medium to be evaluated. Some characteristics, like.the fibrous support fiber diameters and the thickness of each layer, are also quantified. The porous structures of each layer are first described from a global standpoint in terms of mean porosity and pore size distribution obtained by the mercury porosimetry technique. Micro-tomography data are treated to calculate mean porosity values of each layer that are compared to those obtained by mercury porosimetry, and to represent porosity profiles through each layer thickness to give orders of magnitude of the through-plane porosity gradients that they exhibit. In order to evaluate the in-plane homogeneity of the fibrous support porous structure, micro-tomography data are then used to estimate local porosity values from analyses carried out on two different sample areas. The pore sizes of the polymer membrane are evaluated by analysis of 2D images obtained by micro-tomography, and a good agreement is highlighted with those obtained by mercury porosimetry. (C) 2017 Elsevier B.V. All rights reserved.