Nanomechanical Characterization of Functional Cellulosic Fibres

• Applicant: Professor Dr. Robert Stark
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405549611

For the development of functional papers in areas such as electronics, microfluidics or diagnostics it is essential to predict the properties of single fibres after processing and modification. The characteristics of the fibres vary within a fibre and also between the fibres. The objective of this project is thus to characterize functional fibres and fibre joints with respect to their mechanical parameters (flexural stiffness and tensile strength) and the impact of humidity on these parameters with high spatial resolution. This, also the variability of these parameters on individual fibres and between different fibres will be assessed.Because of its excellent spatial and force resolution, the atomic force microscope (AFM) will be the main experimental tool for the characterization of the cellulosic fibres. In addition chemometric mapping will be carried out by using confocal Raman spectroscopy, which will help to directly map polymer coatings. Thus, the distribution of the functional polymer within the fleece and on the fibres will be determined and the impact of the coating on wetting and water uptake and thus the mechanical properties will be assessed. The nanoscale characterization of mechanical properties with the AFM allows one visualize the distribution of the polymer on the fibre surface and bulk near the surface on a very small scale and to verify changes in the mechanical properties such as stiffness with very high sensitivity. Image processing and correlation with light, electron and Raman microscopy yield a detailed picture about the distribution of the polymer in the fleece and its impact on the mechanical properties.A better knowledge of the local mechanical properties and the nanomechanical picture of the water uptake helps to improve the methods and processes for paper making and modification which are used in this consortium and provides input parameters for numerical modelling. As an added value the synergies in this consortium will thus contribute to a more detailed picture of water uptake in functional papers and the impact of humidity on the mechanical properties of the fleece.

• DFG Programme: Research Grants