In-plane moisture transport in paper detected by magnetic resonance imaging

Magnetic resonance imaging was used to visualize in-plane moisture transpor t in laboratory-made handsheets, heavy paperboard, and polyethylene-coated paperboard. Beginning with wet samples sealed on both surfaces, the moistur e content was reduced through evaporation from the outside edges. The diffu sion of moisture to the outside edges, i.e., in the plane of the sheets, wa s found to be isotropic with respect to the sample machine and cross direct ions. Isotropic in-plane moisture diffusion was observed for samples exhibi ting a relatively high degree of fiber orientation, and under conditions of forced convection with air flow rates up to 10 L/min past the outside edge s.