MEASURING MOISTURE GRADIENTS IN CELLULOSE FIBER NETWORKS - AN APPLICATION OF THE MAGNETIC-RESONANCE-IMAGING METHOD

A magnetic resonance imaging method was employed to measure moisture d istributions in pulp samples. A calibration experiment shows that, in the range of moisture contents up to 1.4 g water/g dry substance, the MRI signal is linearly proportional to the mass of moisture of the pul p sample. The in-situ drying of a pulp sheet approximately 4 mm thick was them studied. The resolution in the thickness direction was 0.39 m m. It was found that, even at the very low drying rates employed in th e present study (the average drying rate was 0.3 kg/m(2)/h), a gradien t in moisture developed across the sheet as drying progressed.