Microstructural analysis of paper using synchrotron X-ray microtomography: numerical estimation of the permeability and effective thermal conductivity

Abstract

International audienceSynchrotron X-Ray microtomography has already been successfully applied to visualise the inner structure of various grades of papers at a micron scale. The image analysis tools, previously developed, can provide quantitative data characterising the microstructures of papers. We studied two widely different samples - a Eucalyptus pulp handsheet and a commercial blotting paper. Numerical calculations were carried out on the tomography data to evaluate two specific physical properties - effective thermal conductivity and permeability. The Representative Elementary Volume (REV) for each physical quantity considered, in terms of its 3 characteristic lengths in the three main directions, was defined by the respective correlation lengths (L-c). Despite the small imaged volume (1400 pm x 1400 pm x paper-thickness), for any given property, whether microstructural or physical -: The REV characteristic lengths were similar for both samples, The REV was smaller than the imaged volume, These results validate our approach and indicate that it may be extrapolated to other properties, for example, elastic properties