Experimental and Computational Micro-Characterization Techniques in Wood Mechanics

WG1: Wood microstructure

In this working group, scientific activities focus on increasing and consolidating the current knowledge of the wood structure at the sub-micrometre scale. Investigations will be mainly based on the application of microscopic, spectroscopic, and X-ray techniques, which are specified in detail in the list below. Enhanced insight will be gained by using samples that have been treated mechanically or modified thermally, chemically, genetically, or with enzymes. For this purpose, close cooperation with specialists on modification techniques will be sought.

The molecular structure of the wood cell wall will receive special attention. The accessibility of different regions in the cell wall to moisture will be investigated and will allow for refinement and improvement of current models of the nanostructure. For example, possible water accessibility in the microfibril bundles will provide indications on the existence and spatial arrangement of amorphous structures in these aggregates. A closely related research topic, which will also be studied in this Action, is the cross-linking structure of the cellulose microfibrils and the surrounding hemicelluloses. Investigations will cover the influence of moisture on the arrangement and interlinking of the cell wall polymers. They will be accompanied and complemented by molecular kinetics considerations. Improved knowledge of the bonding structure is expected to enhance the understanding of the molecular origin of the time-dependent material behaviour and the influence of moisture. Moreover, a more detailed model of the spatial arrangement of the wood polymers will also contribute to elucidate the contribution of ultrastructural features to the transverse anisotropy of hygro-mechanical properties of wood at the macroscale.

Further insight into the wood microstructure is expected from performing microstructural investigations under external strain and/or changes of the environmental conditions, particularly of the relative humidity and temperature. Such tests are described in more detail in the framework of Working Group 2.