University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal

Logo BOKU Resarch Portal

Gewählte Doctoral Thesis:

Tillmann Meints (2018): Nutzbarmachung von Holz durch Verständnis für die Holzfarbe und zwei verschiedene Imprägnierungen zur Dimensionsstabilisierung.
Doctoral Thesis - Institut für Holztechnologie und Nachwachsende Rohstoffe, BOKU-Universität für Bodenkultur, pp 80. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
24 local wood species were measured in the CIELab colour system and a database of mean wood colours was created. A model based on light absorption, surface roughness and internal structure (refraction) is proposed to clarify the formation of wood colour. The model also explains the “intensification-effect” (colour enhancement) of wood: by moistening, oiling or varnishing (transparent) wood, white stray light is retained and the surface appears darker and more colourful. At the same time, the Light Reflection Depth was determined for selected wood species - the layer thickness of a wood surface that influences the wood colour (up to 1.4 mm). In order to improve the dimensional stability of European oak and thus expand its possible applications, samples were impregnated with polyethylene glycol (PEG) using a vacuum-pressure process. With this fast method - usually wood is simply stored in PEG solution for a longer period of time - very high loads of up to 42 % could be achieved. Related to water-saturated samples, an anti-shrink efficiency (ASE) of up to 81 % could be achieved. By using silane functional PEG the leaching could be significantly reduced, however ASE decreased. The extremely poor impregnability of spruce could be overcome by dissolving epoxy functional siloxane with supercritical CO2 and loading it into the wood under very high pressure. On a laboratory scale, the method shows that aspirated pits are no obstacle to loading with up to 63 % siloxane. However, since the ASE for less loaded samples is at the same level - about 21 % - it is assumed that such high loads are achieved by filling of cell lumens. This was confirmed by SEM and EDX measurements. The investigations and achievements of the present work have made valuable contributions to the understanding of the wood colour and the modification of important domestic wood species and their utilisation.

Betreuer: Gindl-Altmutter Wolfgang
1. Berater: Müller Ulrich
2. Berater: Liebner Falk

© BOKU Wien Imprint