• Membrane and Water Treatment
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• v.14 no.4
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• pp.175-180
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• 2023

Mixed matrix membranes (MMMs) can be a promising alternative for the solution of dye removal from coloured effluents. Polymeric membranes are widely used due to their good film-forming ability, flexibility, separation properties, and cost. However, they have low mechanical, chemical, and thermal resistances. Moreover, the fouling of polymeric membranes is high because of their hydrophobic nature. Hence, there is an increasing interest in organic-inorganic hybrid membranes as a new-generation membrane material. It has been shown that carbon nanotubes have the potential to increase the material properties of polymers with their low density, high strength, hardness, and exceptional aspect ratio. In this work, carbon nanotubes blended MMMs were prepared and methyl orange removal efficiency of them was investigated. Compared to the bare membranes, MMMs showed not only increased hydrophilicity, water content, and pure water flux but also increased methyl orange rejection and flux recovery

• Textile Coloration and Finishing
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• v.17 no.1
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• pp.7-13
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• 2005

Continuous and intense UV irradiation on PTT film using two types of UV bulbs at different irradiation power level was carried out to modify surface characteristics of the film including zeta potential, wettability, surface energy, and dyeability. ESCA analysis of the irradiated film showed higher O/C ratio than the untreated film indicating photooxidation of outer surface layer. ATR analysis showed that the ester bonds were broken and some new groups were produced such as carboxylic acid, phenolic hydroxy, and other esters, implying that ester bonds of PTT was responsible for the observed photooxidation effect. The surface of the treated PTT film became more hydrophilic and wettable to water, coupled with increased surface energy. Polar component of the surface energy increased and nonpolar component decreased with increasing irradiation energy. The treatment also decreased zeta potential of the modified surface and nanoscale roughness increased with increasing irradiation. The dyeability of the treated films to catonic dyes was significantly improved by electrostatic and polar interaction between dye molecules and the anionic film surface. The UV irradiation seems to be a viable polymer surface modification technology, which has advantages such as no vacuum requirement and continuous process unlike plasma treatment.

• Polymer(Korea)
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• v.34 no.1
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• pp.58-62
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• 2010

The acrylic monomers were graft-polymerized to starch as matrix polymer by emulsion polymerization. Viscosity and particle size of the emulsion were increased with starch contents due to interaction with water and particle swelling toward the water phase by hydroxy group of starch. Chemical stability of the emulsion was also increased with enhancement of starch, but water and alkali resistance were reduced with increasing starch contents because of the increasement of hyrophilicity. Opacity of the starch-acrylic emulsion compound containing calcium carbonate was decreased with contents of starch by its intrinsic color. The film of starch-acrylic polymer showed more clear appearance with increasing starch contents owing to enhancement of amorphous state.

• Journal of the Korean Society of Clothing and Textiles
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• v.14 no.1 s.33
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• pp.13-19
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• 1990

The water-vapor sorption isotherms of viscose rayon and of modified viscose rayon were studied to elucidate the change of sorptivity by the DMDHEU resin finish. To determine the sorption isotherms, moisture regains of the samples were measured at various humidities. The sorption isotherms were determined by the BET and GAB multilayer adsorption theories. The adsorption isotherm of the starting rayon was Brunauer Type II while with increasing resin content those of the DMDHEU-treated rayon became progressively more like Type IV. The DMDHEU-treated samples appeared to be hydrophilic due to the hydrophilicity of DMDHEU although moisture regains at higher humidities markedly decreased because of an impediment in swelling by crosslinkings. The $W_{m}$ value and surface area of crosslinked samples increased with increasing resin content. VR-R-6 which was the most heavily crosslinked viscose rayon had the highest $W_{m}$ and surface area values among all the samples. Relative sorption hysteresis was decreased as humidity increased for all samples. The untreated viscose rayon appeared to have a higher value than the DMDHEU-treated rayon.

• Journal of the Korean Society of Clothing and Textiles
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• v.8 no.1
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• pp.39-45
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• 1984

The effects of Temperature on the removal of triglyceride were studied with soaps having various chain lengths of alkyl group. Cellophane, polyester film and alkali-treated polyester film were soiled with tripalmitin, tagged with 0" and detergency was evaluated by analysing the tripalmitine on the fabric before and after washing by means of liquid scintillation counting. The results were as following: 1) Triglyceride was completely removed from cellophane in distilled water without surfactant at any temperature, because of the hydrophillic nature of cellulose. The detergency of triglyceride from polyester film fully depended on the state of tripalmitin. The detergency of alkali treated polyester film was better than that of untreated polyester film at lower temperature due to increased hydrophillcity, but worse at higher temperature due to the diffusion of molten tripalmitin into the grooves, formed by alkali treatment. 2) The detergency from polyester film was increased with elevating temperature and after reaching some optimum detergencies, the detergencies were rather decreased with increasing temperature. The temperatures of optimum detergency were shifted to higher with increasing chain length of alkyl group. 3) When the soiled film was baked at $60^{\circ}C$ and $70^{\circ}C$ for 20 min, the detergency vs. temperature was much the same as the case of without-baking. These results indicate that the detergency of triglyceride was largely correlated with the suspending power of surfactants at low temperature and with state of soil and hydrophilicity of substrates with elevating temperature.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.33-38
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• 2009

Poly(vinyl acetate) films containing benzophenone were photocrosslinked by continuous UV irradiation.UV irradiation of PVAc film containing 5% benzophenone induced bulk crosslinking of the polymer indicated by 84.1% of gel fraction after ethyl acetate extraction. The crosslinking was attributed to the recombination of tertiary polymer radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of benzophenone. Also the UV irradiation resulted in scission of ester linkage and photooxidation of PVAc surface, which was verified by ATR and zeta potential analysis, implying that the PVAc surface became more polar and hydrophilic. The zeta potential proportionally increased from +4.5mV to -26.8 mV with increasing UV irradiation. Also the surface energy of the PVAc film increased with higher UV irradiation upto 56.5 $mJ/m^2$ by the enhanced Lewis acid/base component with larger contribution of Lewis acid parameter. Accordingly the crosslinked PVAc showed higher thermal stability with increasing UV energy.

• Computers and Concrete
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• v.23 no.5
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• pp.351-359
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• 2019

In this study, the calcium hydroxide, an inherent product of cement hydration, was treated using biomimetic carbonation method of incorporating stearic acid to generate the hydrophobic calcium carbonate on concrete surface. Carbonation reaction was carried out at various $CO_2$ pressure and temperatures and utilizing the Scanning Electron Microscope (SEM), chloride-ion penetration test apparatus, and compression test machine to investigate the hydrophobicity, durability, and mechanical properties of the synthesized products. Experimental results indicate that the calcium stearate may change the surface property of concrete from hydrophilicity to hydrophobicity. Increasing reaction temperature can change the particles from irregular shapes to needle-rod structures with increased shear stress and thus favorable to hydrophobicity and microhardness. The contact angle against water for the concrete surface was found to increase with increasing $CO_2$ pressure and temperature, and reached to an optimum value at around $90^{\circ}C$. The maximum static water contact angle of 128.7 degree was obtained at the $CO_2$ pressure of 2 atm and temperature of $90^{\circ}C$. It was also found that biomimetic carbonation increased the permeability, acid resistance and chloride-ion permeability of the concrete material. These unique results demonstrate that the needle-rod structures of $CaCO_3$ synthetized on concrete surface could enhance hydrophobicity, durability, and mechanical properties of concrete.

• Membrane Journal
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• v.30 no.5
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• pp.293-306
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• 2020

Increasing harmful effects of climate change, such as its effect on water scarcity, has led to a focus on developing effective water purification methods to obtain pure water. Additionally, rising levels of water pollution is increasing levels of environmental degradation, calling for sources of water treatment to remove contaminants. To purify water, osmotic processes across a semipermeable membrane can take place, and recent studies are showing that incorporating nanoparticles, including carbon quantum dots (CQDs), graphene carbon dots (GQDs), and graphene oxide quantum dots (GOQDs) are making thin film composite (TFC) membranes more effective by increasing water flux while maintaining similar levels of salt rejection, increasing the hydrophilicity of the membrane surface, showing bactericidal properties, exhibiting antifouling properties to prevent accumulation of bacteria or other microorganisms from reducing the effectiveness of the membrane, and more. In the review, the synthesis process, applications, functionality, properties, and the role of several types of quantum dots are discussed in the composite membrane for water purification.

• Polymer(Korea)
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• v.27 no.5
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• pp.449-457
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• 2003

The purposes of this work were the producing of a biodegradable poly($\varepsilon$-caprolactone) (PCL) / poly(ethylene oxide) (PEO) microcapsule and the analyzing of form and features for the manufacturing conditions which could be observed in a prospective drug delivery systems through drug release. The effects of emulsifier, emulsifier concentration, and stirring rate for the diameter and form of the microcapsules were observed using image analyzer and scanning electron microscope. The role of interfacial adhesion between PCL/PEO and drug was determined by contact angle measurements, and the drug release test of the microcapsules was characterized by UV/vis. spectra. As a result, the microcapsules were made in spherical fonns with a mean particle size of 170 nm∼68 $\mu$m. And the work of adhesion between water and PCL/PEO increased with increasing the content of PEO, probably due to the increased the hydrophilicity. It was also found that the drug release rate from the microcapsules significantly increased with increasing the content of PEO, which could be also attributed to the increasing of the hydrophilic groups or the degree of adhesion force at interfaces.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.87-93
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• 2004

Recently, with the development of bio-technology the interests in the micro-fluidic devices for analysis in the fields of biology and medical science have been steadily increasing. Although polymer is considered as one of the best materials for micro-fluidic devices. glass or silicon molds fabricated by photo-lithographic technique have been commonly used. However, it is generally perceived that the conventional photolithographic technique has the limitation for fabricating micro-channels for micro-fluidic devices. In this work, the possibility of fabrication of micro-fluidic channels on PDMS by using the mechano-chemical process and the effect of surface states on the fluid flow were investigated. Experimental results revealed that PDMS mold fabricated by the mechano-chemical process could be used effectively to replicate micro-fluidic channels with high reproducibility and dimensional accuracy. It was also found that the fluid flow generation and flow speed were largely affected by the hydrophilicity and the surface roughness of the micro-channel surfaces.