Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Biomaterials

MM 11.4: Talk

Monday, March 20, 2017, 12:30–12:45, IFW D

Nanoscale mechanical properties of wood: Effects of heat treatment and sample preparation — •Salimeh Saleh¹, Dominik Tönnies¹, Maximilian Wentzel², Holger Militz², and Cynthia Volkert¹ — ¹Institute of Materials Physics, University of Göttingen, Germany — ²Department of Wood Biology & Wood Products, University of Göttingen, Germany

The mechanical properties of wood depend on both the complex hierarchical cellular structure and on the mechanical behavior of the constituent materials. Here, we use nanoindentation to investigate the local mechanical properties of the cell walls, with the goal of understanding how they contribute to the bulk mechanical behavior of wood. Quantitative nanoindentation studies require however a smooth specimen surface. Up until now, this has usually been achieved by using specific embedding materials that unfortunately enter the cell wall, thereby changing their mechanical properties. Here, we investigate methods to prepare suitable nanoindentation specimens using (ultra) microtome from Pine wood and Eucalyptus wood that is either unembedded or embedded with materials such as paraffin that do not enter the cell walls. The Eucalyptus wood is an untreated state and heat-treated at various temperatures and water vapor pressures. We observe that the wood samples become highly heterogeneous after heat treatment: In some regions the elastic modulus is high (~100 GPa), while in other regions it is low (~5 GPa). A possible explanation is that the cellulose becomes spatially localized after heat treatment.