Imbibition Into Highly Porous Layers of Aggregated Particles

Imbibition into Highly Porous Layers of Aggregated Particles

Sven O. Schopf, Andreas Hartwig, Udo Fritsching and Lutz Mädler*

* Foundation Institute of Materials Science (IWT), Department of Production Engineering, University of Bremen, Badgasteiner Str. 3 in 28359 Bremen, Germany. (E-mail: [email protected], phone: +49-421-218-51200, fax: +49-421-218-51211)

SUPPORTING INFORMATION

Fig. S1: Influence of storage time on the imbibition velocity for a lamination pressure of 0.35 MPa...... S2 Fig. S2: Influence of storage time on the imbibition velocity for a lamination pressure of 3.4 MPa...... S2

To analyze the influence of layer restructuring on the imbibition process, imbibition experiments of di-water after different storage times of the nanoparticle layers were performed. With increasing storage time, the wettability and hence the capillary force acting on the nanoparticle layer decreases as described in the experimental section. Furthermore, formation of capillary bridges through condensation of humidity increases the stability of the layer. Both effects reduce the occurring restructuring of the layer during the imbibition process with increasing storage time. The results are shown in Fig. S1 and S2. The imbibition velocity decreases with increasing storage time. Hence, the flow resistance of the nanoparticle layers increases with decreasing restructuring of the layer during the imbibition process. In case of the higher lamination pressure, this effect is weaker because the layer has already a higher stability after the lamination process. Besides, the decrease of the straight-line imbibition velocity with the straight-line flow length (slope of the curve) increases with increasing storage time. Thereby, the exponent b increases from around 1.04 or 1.08 for the two lamination pressures and storage times up to one month to about 1.31 for storage times above 27 month. Thus, the amount of crossflow from the large into the small pores increases through the reduction of layer restructuring during the imbibition process. The lamination pressure has no significant influence on the decrease of the straight-line imbibition velocity with the straight-line flow length (exponent b). For storage times of more than 27 month, the imbibition velocities of both lamination pressures converge. After this storage time, restructuring during the imbibition process is prevented even for the lower lamination pressure. S2 Sven O. Schopf, Andreas Hartwig, Udo Fritsching and Lutz Mädler

Fig. S1 Influence of storage time on the imbibition velocity for a lamination pressure of 0.35 MPa. With increasing storage time, the straight-line imbibition velocity is continuously decreasing. Thereby, the decrease of the straight-line imbibition velocity with the straight-line flow length (slope of the curve) increases.

Fig. S2 Influence of storage time on the imbibition velocity for a lamination pressure of 3.4 MPa. The straight-line imbibition velocity decreases with increasing storage time. However, the effect is weaker compared to the lower lamination pressure (Fig. S1). With increasing storage time, the decrease of the straight-line imbibition velocity with the straight- line flow length (slope of the curve) increases.