Investigation of the cellulose-water relationship by the pressure plate method

The water retention properties of papermaking fibers have been investigated by a "pressure plate" technique which permits a measurement of equilibrium moisture contents of pulp samples at precisely controlled relative vapor pressures between 0.99 and 1.00. This range encompasses the water contents of interest in papermaking from the table to the middle of the drier section. Water retention isotherms are drawn and are satisfactorily related to desorption isotherms which have been reported in the literature. Isotherms for a variety of pulps are reported. These are related to the papermaking properties of the fibers and show the effects of wood species, cooking method, pulp yield, bleaching, drying, and beating on the cellulose-water relationship.