In-situ Untersuchung der Nanostruktur von Fichtenholz unter Einfluss von Zuglast und Feuchtigkeit mit Hilfe von Röntgenstreuung

Author(s)

Alexander Müllner

Abstract

Wood is a widely available natural resource with good cost-efficiency and it is one of the most important materials for construction purposes. The high strength and fracture toughness of wood are desirable properties, whereas humidity could be a limiting factor because it is often accompanied by swelling, softening or fungal infestation.
To investigate structural changes on the nanoscale, in-situ X-ray scattering of spruce wood by varying load and humidity was performed. An X-ray transparent chamber was developed, which makes measurements at variable strains in a wide air humidity range between 0 and 100% possible. Both Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS) were performed to investigate different parts of the nanostructure of wood. The WAXS signal was detected with an imaging plate at a sample-to-detector distance of 5,1 cm, whereas the SAXS intensity passed through a hole in the WAXS imaging plate and
was detected at a distance of 65,6 cm by a second imaging plate. The microfibril-angle and cellulose lattice spacing of the wood samples were evaluated from both SAXS and WAXS intensities.
The results show that the laboratory X-ray intensities are not sufficient to measure a dependence on the strain as successfully reported from synchrotron experiments. A possible explanation for this is the fact that the samples showed strong relaxation effects during the time of exposure to the X-ray beam. However, the influence of humidity could be clearly detected: An increasing crystal lattice spacing was observed and can be explained with the swelling of fibrils by water uptake.

Organisation(s)

Dynamics of Condensed Systems

No. of pages

87

Publication date

2017

Austrian Fields of Science 2012

103015 Condensed matter

Portal url

https://ucrisportal.univie.ac.at/en/publications/insitu-untersuchung-der-nanostruktur-von-fichtenholz-unter-einfluss-von-zuglast-und-feuchtigkeit-mit-hilfe-von-roentgenstreuung(4d3dbd4f-7e89-4ccb-bc43-9c8f3ddafabc).html