• Membrane and Water Treatment
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• v.15 no.1
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• pp.31-39
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• 2024

The flow in a nanopore of filtration membrane is often multiscale and consists of both the adsorbed layer flow and the intermediate continuum fluid flow. There is a controversy on which interface the slippage should occur in the nanopore filtration: On the adsorbed layer-pore wall interface or on the adsorbed layer-continuum fluid interface? What is the difference between these two slippage effects? We address these subjects in the present study by using the multiscale flow equations incorporating the slippage on different interfaces. Based on the limiting shear strength model for the slippage, it was found from the calculation results that for the hydrophobic pore wall the slippage surely occurs on the adsorbed layer-pore wall interface, however for the hydrophilic pore wall, the slippage can occur on either of the two interfaces, dependent on the competition between the interfacial shear strength on the adsorbed layer-pore wall interface and that on the adsorbed layer-continuum fluid interface. Since the slippage on the adsorbed layer-pore wall interface can be designed while that on the adsorbed layer-continuum fluid interface can not, the former slippage can result in the flux through the nanopore much higher than the latter slippage by designing a highly hydrophobic pore wall surface. The obtained results are of significant interest to the design and application of the interfacial slippage in nanoporous filtration membranes for both improving the flux and conserving the energy cost.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1821-1823
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• 1999

Carbon is an attractive material on electro double capacitor which depend on charge storage in the electrode/electrolyte interfacial double layer. Carbonaceous material for double layer capacitor can be obtained from carbon powder, fiber, film and porous carbon sheet. The capacitance of electrodes using an activated carbon was influenced by a filling density of the carbon, thickness and internal resistance of the electrode. In this study. to reduce internal resistance and increase electric conductivity of the electrode. activated carbon/carbon(AC/C) composite electrode was fabricated. The capacitors which have energy densities of 68F/g(at $30^{\circ}C$), 109F/g(at $60^{\circ}C$) and $68F/cm^3$(at $30^{\circ}C$), $111F/cm^3$(at $60^{\circ}C$) were fabricated by using AC/C composite electrodes.

• Polymer(Korea)
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• v.36 no.3
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• pp.338-343
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• 2012

Interfacial properties of commercially available soft contact lens hydrogels were studied to understand thermodynamic phenomena of protein adsorption. Hydrogel particles ($1{\times}1mm^2$) with varying water wettability were exposed to bovine serum albumin solutions for an hour. The remained albumin solutions were analyzed with Bradford assay method. The amount of protein adsorbed to hydrogels increased with protein solution concentrations following Langmuir isotherm. The partition coefficient ($P$) and Gibbs free energy cost of dehydrating the surface region by protein displacement upon adsorption increased with increasing hydrophilicity of contact lens. Understanding of physical chemistry in protein adsorption to contact lens materials enabled elucidating relationships between surface energy and albumin adsorption capacity.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.33-36
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• 2010

Multilayer mirrors are very useful for applications of high energy X-ray. X-rays of high energy require very small thickness, a few nanometers, in the d-spacing of a multilayer mirror. Each layer is composed of a multilayr mirror influences to interfacial roughness or interdiffusion which gives rise to degrade specular reflection. Carbon layer of 1 nm thick in a C/W multilayer mirror of 3.25 nm d-spacing was examined. Carbon as well as tungsten layers were very uniform, and there was no micro-structure in carbon layers. However, interdiffusion between carbon and tungste layers was observed by a transmission electron microscope.

• Polymer(Korea)
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• v.24 no.4
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• pp.499-504
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• 2000

The effect of anodic oxidation on high strength PAN-based carbon fibers has been studied in terms of surface functionality and surface energetics of the fiber surfaces, resulting in improving the mechanical properties of composites. According to FT-IR and XPS measurements, it reveals that the oxygen functional groups on fiber surfaces induced by an anodic oxidation largely influence the surface energetics of fibers or the mechanical interfacial properties of composites, such as the interlaminar shear strength (ILSS) of composites. According to the contact angle measurements based on the wicking rate of a test liquid, it is observed that anodic oxidation does lead to an increase in surface free energy of the carbon fibers, mainly due to the increase of its specific (or polar) component. From the surface energetic point of view, it is found that good wetting plays an important role in improving the degree of adhesion at interfaces between fiber and epoxy resin matrix of the resulting composites. Also, a direct linear relationship is shown between 01s/01s ratio and ILSS or between specific component and ILSS of the composites for this system.

• Polymer(Korea)
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• v.27 no.5
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• pp.484-492
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• 2003

How the characteristics and stability of the rubbing-induced alignment of nematic liquid crystals (LCs) relate to the interfacial characteristics of LC-polyimide has been studied. The characteristics of the LC alignment (such as the LC texture, the pretilt angle, and the anchoring energy) and their thermal stability have been investigated for 5 polyimides synthesized for this work. The work showed that the rubbed polyimide alignment layer induces the strong LC anchoring and that the characteristics and stability of LC alignment are determined by the short-ranged interactions between LC and polyimide molecules at the alignment layer surface. The increased flexibility of the polyimide accelerates thermal imidization, increases the pretilt angle, and improves the alignment stability. It also turned out that fluorination of the polyimide tends to deteriorate the alignment uniformity and stability. No distinct differences in the alignment characteristics were shown for the aromatic- and alicyclic-dianhydride polyimides.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.2
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• pp.70-77
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• 1999

The disturbance of oil-water interface confined between tandem fences caused by a sequence of traveling vortices below the interface is investigated. The traveling vortices are assumed to be those detached from the tip of the fore fence. The potential flow is assumed and the density interface is replaced as a sheet of vortex. The shape of the interface is predicted by tracing a finite number of marker particles placed at the interface. The velocity of the marker particles is determined by the Biot-Savart integral along the vortex sheet plus the contribution from the traveling point vortices. The rate of change of vortex-sheet strength is predicted by using an evolution equation for vorticity. The calculated results obtained for various conditions demonstrate that the large amplitude of interfacial wave following the moving vortek can be generated by the vortices.

• Journal of Adhesion and Interface
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• v.2 no.3
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• pp.1-8
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• 2001

Epoxy composites filled with natural zeolite was prepared to investigate the effects of silane coupling agent, ${\gamma}$-APS (${\gamma}$-aminopropyltriethoxysilane)on the surface free energy, tensile properties and interfacial morphology. The value of Lifshitz-van der Waals component, ${\gamma}{\frac{LW}{SV}}$ for polar was $19.22mJ/m^2$ and increased, while that of Lewis acid-base component, ${\gamma}{\frac{AB}{SV}}$ for polar was $15.27mJ/m^2$ and decreased with the increasing content of ${\gamma}$-APS treatment. It is due that the surface of the zeolite is more coated by hydrophobic of alkyl group than hydrophilic amine or hydroxyl group. The tensile strength and Young's modulus of epoxy system were improved by the treatment with ${\gamma}$-APS due to the strong interface bonding, which was confirmed by SEM.

• Membrane Journal
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• v.33 no.3
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• pp.110-126
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• 2023

In this review, the approaches, properties, and elements involved in the formation of polymeric membranes for various materials are discussed. The present research emphasizes the proficiency in several membrane formation processes such phase inversion, interfacial polymerization, stretching, track etching, and electrospinning. Additionally, the obstacles and applicability of various application manufacturing processes are addressed. Various polymeric membranes are reviewed with regard to significant surface properties such as surface roughness, surface tension, surface charge and surface functional group. Additional enhancements of popular membrane formation processes like phase inversion and interfacial polymerization are required to ensure advancements in membrane efficiency. Analysing the possibilities of modern manufacturing practices like track etching and electrospinning is also crucial.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.303-308
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• 2024

Currently, lithium secondary batteries have been used as medium- or large-sized energy sources such as electric vehicles and energy storage system (ESS) due to their high energy and eco-friendly characteristics. Currently commercialized lithium secondary batteries do not fully meet the demands for high energy density and safety. Many studies on solid electrolytes are being conducted to satisfy these requirements. In order to commercialize a solid electrolyte, it is important to supplement the low ion conductivity and high interface resistance with an electrode compared to the organic liquid electrolyte. Therefore, in this study, oligo(3,4-ethylenedioxythiophene (EDOT)) is added to poly(vinyl alcohol) (PVA), which is a polymer matrix with ion conductivity and sticky characteristics, to decrease the interfacial resistance with the same type of polythiophene (PTh)-based electrode. In addition, the addition of porous silicon dioxide (SiO₂) filler improves lithium salt dissociation ability and increases ionic conductivity. And the electrochemical stability of the solid electrolyte, which has been lowered due to additives, is improved by introducing a cross-linked structure using boric acid (BA).