• Membrane Journal
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• v.20 no.1
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• pp.76-86
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• 2010

This study investigated the effect of 2-butoxyethanol (BE) as a nonsolvent additive, relative humidity and air contact time on the structure formation of microfiltration membranes, permeation and morphology properties in phase inversion process. The membranes were prepared by using polyethersulfone (PES)/Dimethyl formamide (DMF)/p-toluenesulfonic acid (TSA)/Polyvinylpyrrolidone (PVP)/BE casting solution and water coagulant. Casting solutions containing various concentration of BE were exposed to a water vapor, under 60 and 80% of relative humidity for 40 and 90 sec, which would be absorbed on. The correlations between the membrane permeation properties and surface/inner structures of membrane were investigated. The characterization of membranes was carried out by a capillary flow porometer, a FE-SEM and a water permeation test apparatus. The surface structure of PES membranes was affected by the exposure time as well as the relative humidity strongly. Furthermore, the addition of BE helped control surface and inner structure at certain humidity and exposure time.

• Membrane Journal
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• v.19 no.1
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• pp.25-33
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• 2009

PES (polyethersulfone) membranes with highly enhanced their asymmetry were prepared by phase inversion process. The membranes were prepared by using PES/DMF (N,N-dimethylformamide)/TSA (p-toluenesulfonic acid)/PVP (polyvinylpyrrolidone) casting solution and water coagulant. The pre-coagulation of membrane surface which was induced by an addition of TSA as a demixing agent and PVP as a swelling polymer in the PES solution and humid exposure time, played a crucial role in determining morphological properties and the PWP (pure water permeation) performance. The PES solution was coated on polyester film under condition of 80% humidity for a while ($72{\sim}144$ sec) before immersing in a coagulation bath. The characterization of membranes was carried out by a capillary flow porometer, a FE-SEM and a permeation test apparatus. As the thickness of the smallest pore size layer (SPL) decreased, the asymmetry of membrane increased under conditions of 20 wt% of TSA and 10 wt% of PVP in 11 wt% of PES solution during longer humid contact time. As a result, the membranes showed a remarkable increase of PWP.

• Journal of the Korean Wood Science and Technology
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• v.46 no.6
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• pp.703-712
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• 2018

The sound absorption property, hand feel, air permeability and pore size of 25 kinds of traditional Korean natural wallpapers (Hanji) were measured and analyzed in this study. The sound absorption rate of Hanji became larger with increasing of frequency beginning from 3.2 kHz, reached 2 times in frequency range of nearby 4 kHz. The sound absorption rate of Hanji was increased as the permeability was lowered and the pore size was decreased. The sound absorption property of Hanji wallpaper could be improved by manufacturing process such as super calendering process.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.166-169
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• 2004

Microfiltration membranes were prepared from aromatic polyethersulfone (PES) polymer, using aprotic solvent (N-methyl-2-pyrrolidone, NMP) and non-solvent additive (2-methoxy ethanol, 2-ME) by the phase inversion co-process of the vapor-induced phase inversion (VIPI) and the nonsolvent-induced phase inversion (NIPI). According to the change of the additive amount, the solvent amount and the relative humidity, membrane characterization was studied. The non-solvent additive in casting solution played an important role in membrane morphology. During the vapor-induced phase inversion, the relative humidity led to water sorption on the surface of casting dope at which pore formation was generated. The prepared membranes were characterized by scanning electron microscope observations, measurements of capillary flow porometer and pure water flux (PWP). Also the thermodynamic and kinetic properties of membrane-forming system were studied through coagulation value, light transmittance and viscosity.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.8-20
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• 2019

This study was conducted to analyze the pore structure of Yellow poplar. Cross-sectional surfaces of heartwood and sapwood of Yellow poplar (Liriodendron tulipifera) were observed by SEM, and the true density of the heartwood, intermediate wood and sapwood were measured by gas pycnometery, while gas permeability and pore size of heartwood, intermediate wood and sapwood were measured by capillary flow porometery. The pores were classified as through pore, blind pore and closed pore. It was determined that the permeability was increased due to the content and size of through pore being increased although the total porosity of specimen showed slight difference from pith to bark. The content of through pore porosity was 33.754 % of heartwood and 47.810 % of sapwood, showed an increasing trend from pith to bark, however, those for the blind pore porosity and closed pore porosity were 27.890 % and 19.492 % for heartwood and 19.447 % and 4.660 % for sapwood, showed a decreasing trend from pith to bark. The max pore size of specimens was increased by about 5 times from $5.927{\mu}m$ to $31.334{\mu}m$, and mean flow pore size was increased by about 315 times from $0.397{\mu}m$ to $12.437{\mu}m$ from pith to bark.

• Membrane Journal
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• v.27 no.2
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• pp.199-204
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• 2017

In this study, a study was carried out for the separation of metal ions in lignin extract discharged from the pulp process. alumina powders were mixed with DMAc (N, N-dimethylacetamide) solvent and PESf (Polyethersulfone) polymer, PVP (polyvinylpyrrolidone) dispersant was added and slip casting method was used to prepare the membrane. The membrane was measured for pore size through a CFP (Capillary Flow Porometer) device and the surface and cross-section of the membrane were observed through a FE-SEM (Field Emission Scanning Electron Microscope). The flux was calculated by measuring the filtered weight per hour using a separation experiment device. Pore size measurements were performed under increasing pressure from 0 psi to 30 psi. The pore size of the membrane was $0.4{\mu}m$ and the flux decreased from the initial flux value of $6.36kg{\cdot}m^{-2}{\cdot}h^{-1}$ to $1.98kg{\cdot}m^{-2}{\cdot}h^{-1}$ due to the fouling of the membrane. After the permeation experiment, membrane contaminants were removed by simple washing. Separation experiments showed that Na contained in the initial lignin extract was reduced by 69%, Fe was removed by 87%, K by 95%, Ca by 93% and Mg by 96%.

• Journal of Powder Materials
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• v.22 no.2
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• pp.87-92
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• 2015

Metallic porous materials have many interesting combinations of physical and geometrical properties with very low specific weight or high gas permeability. In this study, highly porous Cu foam is successfully fabricated by a slurry coating process. The Cu foam is fabricated specifically by changing the coating amount and the type of polyurethane foam used as a template. The processing parameters and pore characteristics are observed to identify the key parameters of the slurry coating process and the optimized morphological properties of the Cu foam. The pore characteristics of Cu foam are investigated by scanning electron micrographs and micro-CT analyzer, and air permeability of the Cu foam is measured by capillary flow porometer. We confirmed that the characteristics of Cu foam can be easily controlled in the slurry coating process by changing the microstructure, porosity, pore size, strut thickness, and the cell size. It can be considered that the fabricated Cu foams show tremendous promise for industrial application.

• Journal of Powder Materials
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• v.22 no.2
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• pp.100-104
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• 2015

The porous metals are known as relatively excellent characteristic such as large surface area, light, lower heat capacity, high toughness and permeability. The Fe-Cr-Al alloys have high corrosion resistance, heat resistance and chemical stability for high temperature applications. And then many researches are developed the Fe-Cr-Al porous metals for exhaust gas filter, hydrogen reformer catalyst support and chemical filter. In this study, the Fe-Cr-Al porous metals are developed with Fe-22Cr-6Al(wt) powder using powder compaction method. The mean size of Fe-22Cr-6Al(wt) powders is about $42.69{\mu}m$. In order to control pore size and porosity, Fe-Cr-Al powders are sintered at $1200{\sim}1450^{\circ}C$ and different sintering maintenance as 1~4 hours. The powders are pressed on disk shapes of 3 mm thickness using uniaxial press machine and sintered in high vacuum condition. The pore properties are evaluated using capillary flow porometer. As sintering temperature increased, relative density is increased from 73% to 96% and porosity, pore size are decreased from 27 to 3.3%, from 3.1 to $1.8{\mu}m$ respectively. When the sintering time is increased, the relative density is also increased from 76.5% to 84.7% and porosity, pore size are decreased from 23.5% to 15.3%, from 2.7 to $2.08{\mu}m$ respectively.