Institute of Solid State Physics

WS18SS19WS19SS20WS20SS21WS21      Guidelines for Master Students

Micromechanics of lignocellulosic fibers
Caterina Czibula
Institut für Biobasierte Produkte und Papiertechnik
11:15 - 12:15 Wednesday 15 December 2021 PH01150

Separating wood into its smallest fragments ‒ lignocellulosic fibers (LCFs) ‒ and treating them, leads to products like paper and paperboard which are connected to our everyday needs. An LCF has a complex hierarchical structure, which consists of several layers and anisotropic properties. With 1-5 millimeter in length and a diameter of tens of micrometer, handling of single LCFs is not easy. These characteristics result in a lack of available experimental methods which can provide a detailed characterization of the fibers’ mechanical and structural properties. Since LCFs are the key component of many products, knowledge of their mechanical behavior is essential for improvements. Furthermore, modeling of fiber networks has gained importance and with increasing complexity of the models, the demand for experimental data that accurately represent the fiber’s behavior is rising.
Here, the limits of mechanical techniques for the testing of single LCFs like tensile testing and nanoindentation will be shortly discussed and Brillouin light scattering microspectroscopy (BLSM) as an optical, non-contact method will be introduced. BLSM is based on the inelastic scattering of light and applied in materials science since the 70ies. The method is based on laser light interacting with acoustic phonons, which causes a frequency shift of the Brillouin scattering peaks that can be related to the elastic properties. By differing the scattering geometry, BLSM enables the measurement of the full set of elastic constants in all three dimensions which is crucial for anisotropic materials like LCFs.