For the first time, the three-dimensional (3D) internal structure of naturally produced Didymosphenia geminata frustules were nondestructively visualized at sub-100 nm resolution. The well-optimized hierarchical structures of these natural organisms provide insight that is needed to design novel, environmentally friendly functional materials. Diatoms, which are widely distributed in freshwater, seawater and wet soils, are well known for their intricate, siliceous cell walls called ‘frustules’. Each type of diatom has a specific morphology with various pores, ribs, minute spines, marginal ridges and elevations. In this paper, the visualization is performed using nondestructive nano X-ray computed tomography (nano-XCT). Arbitrary cross-sections through the frustules, which can be extracted from the nano-XCT 3D data set for each direction, are validated via the destructive focused ion beam (FIB) cross-sectioning of regions of interest (ROIs) and subsequent observation by scanning electron microscopy (SEM). These 3D data are essential for understanding the functionality and potential applications of diatom cells.

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This study investigates the possible enhancement of flame resistance in powder-epoxy resin/glass fabric composites. For this purpose, the halogen-free flame retardants containing phosphorous, nitrogen and aluminium were used. The total content of the fillers did not exceed 25 wt%. The laminates assessed for flame retardancy were designed specifically to be used as components of seats in public transport. Thermal resistance of the laminates and the surfaces of partially burned composites were also examined using thermogravimetric and scanning electron microscopy/energy-dispersive x-ray spectroscopy analyses, respectively. On the basis of the obtained results, it was found that the highest flame resistance (V-0 class, minimum oxygen concentration = 35.5% and maximum average rate of heat emission = 38.5 kW/m2 at an incident heat flux of 50 kW/m2) was identified in the laminates with matrix comprising 15 wt% aluminium diethyl phosphinate and 10 wt% melamine polyphosphate. In turn, the laminates with the matrix containing ammonium polyphosphate as the main component achieved only the V-1 flammability class.

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Synthesis and characterization of composite shear thickening fluids (STFs) containing carbon nanofillers are presented. Shear thickening fluids have attracted particular scientific and technological interest due to their unique ability to abruptly increase viscosity in the case of a sudden impact. The fluids have been developed as a potential component of products with high energy absorbing efficiency. This study reports on the rheological behavior, stability, and microstructure of the STFs modified with the following carbon nanofillers: multi-walled carbon nanotubes, reduced graphene oxide, graphene oxide, and carbon black. In the current experiment, the basic STF was made as a suspension of silica particles with a diameter of 500 nm in polypropylene glycol and with a molar mass of 2000 g/mol. The STF was modified with carbon nanofillers in the following proportions: 0.05, 0.15, and 0.25 vol.%. The addition of the carbon nanofillers modified the rheological behavior and impact absorption ability; for the STF containing 0.25 vol.% of carbon nanotubes, an increase of force absorption up to 12% was observed.