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Boehmite nanoparticles show great potential in improving mechanical properties of fiber reinforced polymers. In order to predict the properties of nanocomposites, knowledge about the material parameters of the constituent phases, including the boehmite particles, is crucial. In this study, the mechanical behavior of boehmite is investigated using Atomic Force Microscopy (AFM) experiments and Molecular Dynamic Finite Element Method (MDFEM) simulations. Young’s modulus of the perfect crystalline boehmite nanoparticles is derived from numerical AFM simulations. Results of AFM experiments on boehmite nanoparticles deviate significantly. Possible causes are identified by experiments on complementary types of boehmite, that is, geological and hydrothermally synthesized samples, and further simulations of imperfect crystals and combined boehmite/epoxy models. Under certain circumstances, the mechanical behavior of boehmite was found to be dominated by inelastic effects that are discussed in detail in the present work.The studies are substantiated with accompanying X-ray diffraction and Raman experiments.
We have studied the mechanism of hydrogen storage in the aluminium based metal–organic framework CAU-1 or [Al4(OH)2 OCH3)4(O2C-C6H3NH2-CO2)3] using a complementary multidisciplinary approach of volumetric gas sorption analysis, in situ neutron diffraction and spectroscopy and ab initio calculations. The structure of CAU-1 forms two different types of microporous cages: (i) an octahedral cage with a diameter of about 10 Å and (ii) a tetrahedral cage with a diameter of about 5 Å. Though all metal sites of CAU-1 are fully coordinated, the material exhibits relatively high storage capacities, reaching 4 wt% at a temperature of 70 K. Our results reveal that hydrogen sorption is dominantly driven by cooperative guest–guest interactions and interactions between guest hydrogen molecules and organic linkers. The adsorption of hydrogen on the organic linkers leads to the contraction of the host framework structure and as a result to changes in the electronic potential surface inside the pores. This, in turn, leads to cooperative rearrangement of the molecules inside the pores and to the formation of additionally occupied positions, increasing hydrogen uptake. At the final stage we observe the formation of solid amorphous hydrogen inside the pores.