Swelling of Cellulosic Porous Materials - Mathematical Description and Verification

Abstract

The swelling of natural porous materials, including bleached pulp, as represented by mathematical descriptions, is influenced by a variety of different operating factors. The formerly used Generalised Hygroscopicity Model leads to either a disproportion between a model and a limit value of the sorption capacity or to noticeable deviation in the early swelling phase. Alternatively, the so-called Simple Bounded Growth model solely depends on the maximum sorption capacity, ignoring the physical properties that affect the fibre swelling rate. This research shows that the combination of the two models best describes the swelling process of bleached pulp -a rapid swelling phase and a slower swelling phase. The combined model was found to be useful in characterizing the well-known hornification process.

Transport and evaporation of aqueous co-solvent solutions in thin porous media

“…The inter-fiber pore sizes are in the micrometer range, whereas the intrafiber pores are of nanometer dimensions. For unsized paper, the fiber wall is highly permeable to water, which is a small molecule and reaches pore-fiber equilibrium within a timescale of typically a few seconds [9][10][11]. In contrast, for pure ethylene glycol (EG) it takes 20-400 times longer [9].…”

Archival performance of paper as affected by chemical components: A Review

“…High variations in humidity during storage of paper can be expected to repeatedly change the sizes of such menisci, thereby providing a mechanism by which degradative agents, such as acidity, could become concentrated (Hubbe et al 2017). As explained by Geffert et al (2017), such processes, involving cyclic humidity changes, also can be expected to lead to hornification effects in stored paper items.…”