SUMMARY

The wicking performance of multi-ply paper composed of dissimilar plies has been observed to exceed that of the individual component plies. An investigation was conducted in order to quantify and understand this behavior. Tests were performed using paper samples composed of either hardwood or softwood. Basis weight and void fraction of the samples was similar, while pore size was dissimilar. Tests were performed on single-ply materials as well as the double-ply, dissimilar ply material. Gravimetric wicking tests compare water uptake versus time for vertical, horizontal, and downward wicking arrangements. Capillary pressure and permeability are calculated from experimental data, and the data compared to theory using Darcy's law and the Lucas-Washburn equation. Wicking was also observed using nuclear magnetic resonance (NMR) imaging. The moisture distribution within double-ply samples during wicking was observed. The results of these experiments are presented and combined with the results of gravimetric wicking to construct a hypothesis for the physical mechanisms behind multi-ply wicking enhancement.