Ultra-lightweight cellulose aerogels can be obtained in three steps: (1) preparation of a cellulose solution in molten N-methylmorpholine-N-oxide monohydrate (NMMO·H2O) at 110–120°C and casting of the viscous mass into moulds; (2) extraction of the solidified castings with ethanol to initiate cellulose aggregation and to remove NMMO·H2O so that the fragile, fine-porous texture of cellulose II is largely retained; and (3) drying of the lyogel using supercritical carbon dioxide (scCO2). According to this approach, cellulosic aerogels were prepared from eight commercial cellulosic materials and pulps and analysed for selected chemical, physicochemical and mechanical parameters. The results reveal that all aerogels obtained from 3% cellulose containing NMMO·H2O melts had a largely uniform mesoporous structure with an average pore size of ∼9–12 nm, surface area of 190–310 m2 g-1, and specific density of 0.046–0.069 g cm-3, but rather low mechanical stability expressed as compressive yield strain of 2.9–5.5%. All samples showed viscoelastic behaviour, with Young's modulus ranging from ∼5 to 10 N mm-2. Doubling the cellulose content in the NMMO·H2O melt from 3% to 6% increased Young's modulus by one order of magnitude. Shrinkage of the fragile cellulose bodies during scCO2 drying was still considerable and is subject to further investigations. Influencing parameters such as scCO2 pressure, cellulose content, regenerating solvent and the number of regenerating baths were optimised.

Single carbon fibers are deformed in bending by forming loops with varying radius. Position-resolved x-ray diffraction patterns from the bent fibers are collected from the tension to the compression region with a synchrotron radiation nanobeam of 100 nm size from a waveguide structure. A strain redistribution with a shift of the neutral axis is observed. A significant increase of the misorientation of the graphene sheets in the compression region shows that intense buckling of the nanosized carbon crystallites is the physical origin of different tensile and compressive properties.

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Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

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Simultaneous small‐angle scattering and wide‐angle diffraction using a synchrotron radiation microbeam was applied for the first time to investigate single carbon fibers in a position‐resolved way. Taking into account the exact X‐ray beam profile and examining the fibers in two scattering geometries allowed a discrimination between different models for the internal arrangement of carbon layers and pores. For a fiber based on polyacrylnitrile the carbon layers were randomly oriented within the fiber cross section, whereas in a mesophase‐pitch based fiber the layers were arranged in a radial structure.