Drying of a Compressible Biporous Material

Abstract

We study the consequences of drying on the internal structure of compressible materials containing pores of different sizes, which may be seen as model systems of sponges or wood. With the help of original techniques, we devise biporous media with different relative amounts of small and large pores, and follow the evolution of the liquid fraction simultaneously in each pore type. We show that in a compressible biporous medium with dispersed large pores (i.e., not directly connected) drying induces the homogeneous emptying of the large pores first, due to their compression, along with some compression of the small-pore matrix. In contrast, when the large pores are connected, they successively empty without compression. In both cases, the small pores start or finish to empty in the next stage, and a constant drying rate is observed during most of the time, thanks to liquid films maintaining the contact of the liquid network with the free surface of the sample.

Analysis of water content in wood material through 1D and 2D 1H NMR relaxometry: Application to the determination of the dry mass of wood

“…There is still concerns about use of the latter approach as unwanted signal "coherence pathways" may not be eliminated as effectively as with linear spacing [37]. However, this approach has shown great results for practical applications in wood sciences [38]. In general, T 1 T 2 NMR distribution spectra provide rich information about the different types of water and their "state" inside wood, but for water quantification and dry mass calculations, the resolution obtained by T 2 NMR relaxometry should provide the same results in just a small fraction of the time required for a T 1 T 2 NMR relaxometry experiment.…”

MR Study of Water Distribution in a Beech (Fagus sylvatica) Branch Using Relaxometry Methods

“…The integrated intensity first increased, then it was constant and finally decreased again below MC = 20%. This can be explained by the model of a bioporous system with connected pores [ 38 ]. The T 2 value and the integrated intensity of peak III decreased in the course of drying indicating the homogeneous decrease of water in large pores.…”

“…The multiseriate rays were larger than the earlywood vessels. Therefore, an additional reason for the longer T 2 value was a higher amount of water in ray cells; namely, the T 2 value increased with the water concentration in pores [ 38 ]. These results indicate that in the course of drying of a wood sample, water is diffused from the annual rings to the rays before evaporating from the sample.…”

Wood-Mimicking Bio-Based Biporous Polymeric Materials with Anisotropic Tubular Macropores

“…Previous investigations on the rational design, preparation, characterization and fluid flow transfer properties of poly(2-hydroxyethyl methacrylate) (PHEMA)-based materials with double porosity have been reported by our group and involved different synthetic strategies [ 17 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. The double porogen templating approach was adopted by using a porogenic solvent as a nanoporogen and (non-)sintered sieved NaCl particles or poly(methyl methacrylate) (PMMA) beads as macroporogen templates [ 17 , 26 , 27 , 30 ].…”