Planar,Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

Porous, silicon carbonitride‐based ceramic support structures for potential membrane and catalysis applications were generated from a preceramic polysilazane precursor in combination with spherical, ultrahigh‐molecular weight polyethylene microparticles through a sacrificial filler approach. A screening evaluation was used for the determination of the impact of both porogen content and porogen size on pore structure, strength, and permeability characteristics of planar specimens. By optimizing both the composition as well as cross‐linking parameters, maximum characteristic biaxial flexural strengths of 65 MPa and porosities of 42% were achieved. The evolution of an interconnected, open‐pore network during thermal porogen removal and conversion of the preceramic polymer led to air permeabilities in the order of 10^?14 m². The materials were further exposed to long‐term heat treatments to demonstrate the stability of properties after 100 h at 800°C in oxidizing, inert, and reducing environments. The determined performance, in combination with the versatile preparation method, illustrates the feasibility of this processing approach for the generation of porous ceramic support structures for applications at elevated temperatures in a variety of fields, including membrane and catalysis science.     

Confirmation of the Dominant Defect Mechanism in Amorphous In–Zn–O Through the Application of In Situ Brouwer Analysis

The dominant point defect mechanism of amorphous (a‐) indium zinc oxide (IZO) was probed through in situ electrical characterization of sputtered a‐IZO thin films in response to changes in oxygen partial pressure (pO) at 300C. The results yielded a power law dependence of conductivity (σ) versus pO of ～?1/6. This experimental method, known as Brouwer analysis, confirms doubly‐charged oxygen vacancies as the dominant defect species in a‐IZO. The success of this study suggests that Brouwer analysis is a viable method for studying the defect mechanisms of amorphous oxides.     

Partikelform und Porosität von biogenen Pyrolysekoksen

Char particles from pyrolyzed biomass vary in particle size and shape. On average, the particles are more elongated the larger their size. The average size‐specific elongation is almost alike for all investigated samples, i.e. independent from their source material and process. The particle collectives cannot be characterized accurately with classical particle size distributions, which assume spherical particle shape. Accounting for their shape, they can be described more accurately with particle size distributions that are based on an ellipsoid model. The high bulk porosity is mainly attributed to the spaces between particles.     

Oil‐spill cleanup: The influence of acetylated curaua fibers on the oil‐removal capability of magnetic composites

A magnetic resin based on cardanol, furfural, and curaua fibers was prepared and characterized. The material could be used in oil‐spill cleanup processes, because of its aromatic/aliphatic balance. The resin was prepared through bulk polycondensation of cardanol and furfural in the presence of curaua fibers and maghemite nanoparticles. Hydrophobicity of the curaua fibers was improved by acetylation, increasing the oil‐absorbing capability of the composites. The obtained magnetic composites were studied by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. Degree of cure, magnetic force, and oil‐removal capability tests were also performed. The results show that the composites possess an elevated cure degree in addition to a considerable magnetic force. The materials exhibit a good oil removal capability in the presence of a magnetic field, which is improved by the use of acetylated curaua. In the best case, the composite filled with maghemite and curaua can remove 12 parts of oil from water. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41732.     

Measurement of Helium Leakage Rates through Closures of Dangerous Goods Packagings for the Assessment of Potentially Explosive Mixtures in Freight Containers

The objective was to find out whether an explosive atmosphere can be created in a freight container by gaseous leakage flow of vapour‐air‐mixture through leaks in the closures of dangerous goods packagings filled with hazardous liquids. Because of high temperatures during intercontinental carriage, there is a gauge pressure in the free vapour phase inside the packagings which can cause a gaseous leakage flow. Two different methods were applied: Helium limit leakage rates for 23 quantitatively important hazardous liquids concerning their lower explosion limit (LEL) were calculated for a worst case transport scenario (Method 1). Helium leakage rates of five closure types of dangerous goods packagings with volumes of approximately 6 l were measured using the pressure technique by accumulation (Method 2). All types of closures of steel packagings were uncritical. The maximum measured leakage was 33% of the limit leakage rate. The leakage rates of screw closures of plastic jerricans can exceed the LEL if there are production‐related patterns such as non‐concentricity of the closures and flashes on the neck. Especially for plastic packagings it is important to minimize gaseous leakage flow, because an explosive atmosphere can also be reached by permeation of the individual filling substance or by a combination of both effects. For the assessment of potentially explosive mixtures in freight containers, both mass transfer mechanisms have to be taken into account. Copyright © 2015 John Wiley & Sons, Ltd.