WATER-VAPOR SORPTION EQUILIBRIA OF A BLEACHED-KRAFT PAPERBOARD - A STUDY OF THE HYSTERESIS REGION

The moisture sorption equilibria of a bleached-kraft paperboard (mean basis weight 240 g/m(2)) was investigated experimentally with special attention focused on the hysteresis loop and its interior The theory o f independent domains developed by Everett [11] was utilized to calcul ate a domain or moisture distribution function from experimental bound ary absorption, desorption and secondary desorption isotherms. The moi sture distribution function was used to construct additional EMC paths inside the main hysteresis loop like secondary adsorption curves and spiral trajectories which showed good agreement with experimental data . If recent conjectures regarding correspondence between sorption hyst eresis and hysteresis in dimensional changes, stress-strain behaviour and other paper properties are true, it may be possible to explain and correlate hysteresis in these. other properties also via Everett's th eory of independent domains.