Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 11: Biomaterials

MM 11.3: Vortrag

Montag, 20. März 2017, 12:15–12:30, IFW D

In-situ SEM / TEM fracture tests on (modified) pine sap wood — •Mona-Christin Maaß1, Maximilian Wentzel2, Holger Militz2, and Cynthia Volkert11Institute of Materials Physics, Georg-August-University of Göttingen, Friedrich-Hund-Platz 1, Göttingen, Germany — 2Wood Biology and Wood Products, Georg-August-University of Göttingen, Büsgenweg 4, Göttingen, Germany

There is evidence that intrawall failure of wood occurs at the interface between the S1 and S2 cell wall layer. However, up to now, the fracture mechanisms of the cell wall remain unexplored. Therefore, we performed fracture tests of pine wood tracheid cell walls which are important because pine -- mostly made of tracheid cells -- is very common. Our experimental setup enables us to create a crack in the cell wall and to observe the crack propagation in-situ with an electron microscope.

We have observed that crack propagation is not continuous, but intermittently starts and stops accompanied with a change in propagation direction. We attribute this intermittent behavior to the abrupt change of the microfibril angle at the interface between the S1 and S2 cell wall layer and propose that the resultant increase in toughness is a driving force for the natural adaptation of the layered structure. Additionally, we will investigate pine sap wood that has been heat-treated or modified with a methylol resin. The treated wood has higher resistance against fungi but reduced bending and tensile strength relative to untreated wood. Here, the goal is to understand the reasons for the poorer mechanical properties on the basis of the crack behavior.

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