This document summarizes research using x-ray tomography to characterize the 3D structure of paper at the micrometer scale. Key findings include: (1) The structure is similar across different paper samples with some variation in pore size distribution. (2) Simulations using a layered fiber deposition model with pore filling better match experimental measurements of formation and pore structure than a uniform deposition model. (3) Further work is needed to model variations in porosity and structure with sample size.

1. Generalised description of the three-dimensional structure of paper Christophe Mercier 1 , Martin Dubé 1 , Sabine Rolland du Roscoat 2,3 , Jean-Francis Bloch 3 and Patrice J. Mangin 1 . 1 Centre Intégré en Pâtes et Papiers, Trois-Rivières, Québec. 2 European Synchroton Radiation Facility, Grenoble France. 3 LGP2, PAGORA, Saint-Martin-d’Hères, France Contact: [email_address]

12. Volume dependent porosity X Z Y L 

13. Volume dependent porosity  copy = 0.53 Convergence towards bulk porosity: measurement are statistically representative

14. Formation: copy1, 2, 3, 4 Coefficient of variation of formation indice is 6.35% Copy1 Copy2 Copy3 Copy4 m z,700 23.5538 22.7725 20.2397 25.9833  z,700 8.7201 8.1253 7.8149 8.6236 0.3702 0.3568 0.3861 0.3318

18. Autocorrelation function Mass distribution within a given slice z Equation:

19. Autocorrelation function Mass distribution within a given slice z a,b: characteristic length of decay Ratio a/b describes anisotropy a b

22. Preliminary conclusion (1) Very little differences between samples Variations in porosity, formation, etc… between Samples may be traced back to variations in pore size distributions and mean pore length

34. Questions