| This thesis investigates local permeability of paper and its variation. It was determined by characterizing the local correlations and the impact of flocculation. Paper is bicontinuous structure of fibers and void spaces with both percolating. Models for pores in paper continue to be dominated by the capillaric ones.;In the present work the permeability of paper is calculated from images of actual paper structures, obtained by X-ray microtomographic reconstructions of handsheets of bleached kraft softwood pulp. Pore lengths, radii, connectivities and hydraulic conductance were calculated. A flux balance at pore intersections gives pressure and was used for calculation of the equivalent permeability. The correlation of permeabilities in consecutive images was determined. Fiber networks of different formation numbers were created and permeability variations were analyzed. A better understanding of heterogeneties in paper permeability can help improving performance properties and moisture dependant properties of paper. |
