Toward the link between structural and mechanical properties of fiber aggregates in paper materials

Mechanical properties of fiber-based materials, such as paper, are governed by the heterogeneous microstructure induced by the formation process. For example, in paper materials during tensile tests, lower strains are observed in the flocs (fiber aggregates where the basis weight is larger than the average one) than in the antiflocs (complement of flocs). To explain such behavior, we investigated the mechanical and structural properties of both flocs and antiflocs. Using tensile tests on flocs and antiflocs, we measured their elastic modulus and found that the elastic modulus of flocs was larger than the antiflocs’ one. To understand these differences, a multiscale structural analysis was conducted on 3D X-ray images of flocs and antiflocs at two different spatial resolutions. We found that the floc was thicker than the antifloc, whereas the microscale analysis showed the studied floc and antifloc exhibited the same bulk porosity. Then, it was concluded that the difference in elastic modulus between flocs and antiflocs is mainly due to their thickness difference. Graphical abstract