Papers by Keyword: Nano-Porous Materials

Abstract: The purpose of this study was to investigate the sound proof properties of the double layer acryl plates with various packing materials inside. The acryl plates were filled with vacuum pressure ranged from-20 to-80 kPa, fumed silica as nanoporous materials, and HCFC (hydrochloro-fluorocarbon) as inert gas. The sound pressure level passed though panels was measured to compare soundproof performance. All other panel showed better performance from 500-1000 Hz than air layer panel. For the vacuum layer panel, panel with-80 kPa showed the best performance among other vacuum layer panel throughout all range of frequency. It is found that the more nanomaterial filled in panel, the lower sound proof performance. When it comes to panel filled with inert gas, the sound proof performance improved when it has greater pressure of gas.

Abstract: Through the finite element method, the elastic modulus and Poisson ratio out of plane of the honeycomb nanoporous materials are obtained. In the end, the values are contrasted with the scale values. Results show that the values are same to the scale values.

Abstract: Within a micromechanical framework, the effect of surface energy is taken into account to explore the size-dependent yield criterion of nanoporous materials under complex stress states. A theoretical picture of the yield behavior on an octahedral plane is illustrated as functions of the surface properties and void size. The prominent size dependence of the yield criterion of nanoporous materials highlights the importance of the surface effect in analyzing the strength of nanostructured materials. The results demonstrate a fundamental framework to extend continuum strength theories to the nanoscale with substantial surface effect, which may be useful for evaluating the mechanical integrity of nanostructured materials.

Abstract: The application of interference microscopy (IFM) and infrared microscopy (IRM) to monitor the evolution of the concentration of guest molecules in nanoporous host materials opens a new field of diffusion research in condensed matter. It combines the methodical virtues of the profiling methods of solid-state diffusion studies with the benefit of the mobility enhancement in fluids. We are going to illustrate the rich options of diffusion studies provided by this novel experimental approach.

Abstract: A new method of analysis of PALS spectra of porous materials is proposed. The model considers both the thermalization process of positronium inside the pores and the pore size distribution. The new model is fitted to spectra of mesoporous silica MCM-41 and MSF. The resulting parameters are compared with parameters obtained from fitting the “conventional” models, i.e. a sum of exponential components with discrete or/and distributed lifetimes.

Abstract: Electrochemical processing is a cost effective and low-temperature approach suitable for the fabrication of certain unique nanostructures that are difficult to obtain by other methods. Here we report on the synthesis of nanowires and nanoporous structures with the intention to control the magnetic properties of conventional materials. Nanowires with variable sizes (diameter 15 nm - microns, and length up to 100 microns) have been fabricated by template assisted electrodeposition. Utilizing a combined alloy electrodeposition and electrochemical dealloying approach, porous nanostructures with controlled pore size and porosity have also been synthesized. Magnetization, Curie temperature, coercivity, saturation field, and remnant magnetization of these magnetic nanostructures exhibit much wider tunibility compared to bulk and thin film samples.

Abstract: Oxygen radicals occlusion / release behavior of nanoporous aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4), synthesized under different condition was examined by the temperature programmed reduction (TPR) in an atmosphere of hydrogen in the temperature range of 200-1000°C and temperature programmed oxidation (TPO) measurement at 800°C. From the TPR results of Ca12Al14O33 (X=0) and Ca12Al10Si4O35 (X=4), it was found that there were three oxygen release peaks, denoted as α, β and γ, on each sample and the peaks appeared in the temperature range 300-420°C, 420-600°C, and 600-750°C, respectively. The oxygen contents of α and γ of samples were almost the same. However, the oxygen content of β in the sample with x = 4 was much larger, almost double, compared to that in x = 0. From the TPR, TPO results and catalytic performance, it was concluded that the oxygen content of β peak strongly influenced the catalytic activity of the nanoporous aluminosilicate in the propylene combustion.