Sorptions- und Quellungseigenschaften von verdichtetem Holz

2002

S. 114-116

6 Lit. Ang.

Unselbständiges Werk

200095827

The aim of the investigations was to determine the swelling and the sorption behavior of the densified ash (Fraxinus excelsior L.) and maple (Acer pseudoplatanus L.) form-wood made from small diameter roundwood within the entire hydroscopic range. From this investigations it follows that: - in the monomolecular coverage the densified wood takes up more water than the untreated wood, - the polymolekular sorbed water as well as the fiber saturation point are lowered by the densified wood in comparison to the untreated wood. This is due to the reduction of the void structure of the densified material - in the range of the chemi- and physisorption the densified wood shows higher affinity to the water than the untreated wood. This points on a certain destruction of the internal structure of the densified wood - the accessibility of the sorption active groups of the densified wood is importantly higher compare to the untreated wood. The reason for it is the fact, that by the compression process the hydrogen bonds between the cellulose chains were partly broken and thus the accessibility for the water molecules was increased - the swelling measurements show that starting from approx. RH 75%, (i.e. within the range of the capillary condensation) a substantial swelling incrase take place, which exceeds those of the untreated wood by far.