• Membrane Journal
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• v.26 no.6
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• pp.458-462
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• 2016

Saline water electrolysis, known as chlor-alkali (CA) membrane process, is an electrochemical process to generate valued chemicals such as chlorine, hydrogen and sodium hydroxide with high purities higher than 99%, using an electrolytic cell composed of cation exchange membrane, anode and cathode. It is necessary to reduce energy consumption per a unit chemical production. This issue can be solved by decreasing intrinsic resistance of the membrane and the electrodes and/or by reducing their interfacial resistance. In this study, the electron radiation grafting of a $Na^+$ ion-selective polymer was conducted onto a hydrocarbon sulfonated ionomer membrane with high chemical resistance. This approach was effective in improving electrochemical efficiency via the synergistic effect of relatively fast $Na^+$ ion conduction and reduced interfacial resistance.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1525-1529
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• 2013

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the nucleophilic substitution reactions of 2-pyridyl thionobenzoate (5b) with alkali-metal ethoxides (EtOM, $M^+=Li^+$, $Na^+$, $K^+$, and 18-crown-6-ether complexed $K^+$) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. $[EtOM]_o$ curve upward regardless of the nature of the $M^+$ ions, while those of $k_{obsd}/[EtO^-]_{eq}$ vs. $[EtO^-]_{eq}$ are linear with a positive intercept. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the ion-paired EtOM is more reactive than the dissociated $EtO^-$, and $M^+$ ions catalyze the reactions in the order $K^+$ < $Na^+$ < $Li^+$ < 18C6-complexed $K^+$. The plot of log $k_{EtOM}$ vs. $1/r_{Stokes}$ results in an excellent linear correlation, indicating that the reactions are catalyzed by the solvated $M^+$ ions but not by the bare $M^+$ ions. The reactions of 5b with EtOM have been concluded to proceed through a six-membered cyclic TS, in which the solvated $M^+$ ions increase the electrophilicity of the reaction center and the nucleofugality of the leaving group.

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.14-22
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• 2021

The objective of this study was to investigate the effect of alkali-washing with different sodium hydroxide concentrations on the chemical compositions of steam-treated Betung bamboo strand. Strands were subjected to steam treatment at 126 ℃ for 1 h under 0.14 MPa pressure and followed by washing with 1-5% sodium hydroxide solution for 30 sec. The alteration of structural and non-structural chemical components content of bamboo strands was evaluated. Steam and washing treatments with various concentrations of sodium hydroxide solution considerably reduced the extractive content of bamboo strands, and the cell wall chemical components of the strand in the small degree. FTIR analysis showed noticeable changes in peaks related to hemicellulose and lignin. The relative crystallinity increased significantly after steam and washing treatment with sodium hydroxide up to 3% concentration. SEM Images showed smooth and clean strands surface after washing with 3% sodium hydroxide.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.528-536
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• 2020

In this study, high strength mortar and normal strength mortar using waste glass sand were evaluated. The main parameters studied were mechanical properties, alkali-silica reaction(ASR) and residual mechanical properties after ASR. As a result of this experiment, it was found that the increase in strength of the mortar has a limitation in improving the slip of the waste glass sand(GS), and rather, it causes a larger ASR. However, the possibility of improving the slip of GS was confirmed by the temporary increase of initial residal compressive and flexural strength of the mortar containing GS after the ASR. Therefore, to improve the slip of GS, the additional research is required, such as modification of the surface of GS and the incorporation of a binder which can increase the strength and makes matrix compact.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.5 s.142
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• pp.671-679
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• 2005

Chitosan is the affinitive finishing agent and gives susceptible effect in textile finishing. In order to examine the modification of polyester fabric treated with chitosan, we observed the characteristic of polyester fabric surface and measured its physical properties. For the purpose of confirming the adhesion of cationic material, we made a comparative study on anionic acid dye. The fabric was treated with crosslinking agent after chitosan finishing. Glutardialdehyde as crosslinking agent was used to improve the fixation rate of chitosan on the polyester fabric. And the US value was increased according to increasing of chitosan concentration. As the concentration of crosslinking agent was increased, whiteness index of the fabric chitosan treated was increased. Moisture regain of the fabric treated with $1\%$ chitosan was doubled and that treated with $2\%$ chitosan was tripled comparing with original fabric. Tensile strength of the chitosan treated fabric had been an increase of $10\%$ compared with alkali treated fabric and crease resistance decreased regardless of chitosan concentration.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.861-868
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• 2020

The use of polyphenol extracts from radiata pine (Pinus radiata) bark as raw materials for bio-foams was investigated along with the optimal NaOH extraction conditions. The targeted yield of alkaline extracts was 60%, and the targeted pH was 11 to 12. The radiata pine bark was composed of 70% of a 1% NaOH extract, which contained mainly polyphenols, such as proanthocyanidin (PA). As the particle size of the bark decreased, the yield of the 1% NaOH extracts increased from 57 to 87%. A range of NaOH concentrations, liquor ratios, and extraction times were explored to establish an economic polyphenol extraction method. More than 60% of the alkaline extract was extracted, and the pH of the extract was approximately 12 when the optimum extraction conditions were employed, i.e., a liquor to bark ratio of 5:1, a NaOH dosage of 17 to 18% based on the bark weight, and a 1 h extraction time. Following neutralization of the alkaline extract, structural analysis indicated severe structural changes in the PA during the alkaline extraction. Because the alkaline extract was barely soluble in the solvent used for the structural analyses, it is assumed that chemical modification is required to increase the solubility of the alkaline extract for the production of bio-foams.

• Korean Journal of Food Science and Technology
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• v.23 no.6
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• pp.759-763
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• 1991

The dynamic rheological properties of the dope and the hydrated disperson of the soyprotein, as a starting material of soyprotein fiber, were studied to investigate their viscoelastic properties. The increase of protein concentration in the both cases of the dope and the dispersion resulted in the establishment of intermolecular reaction of the protein. With the addition of alkali solution to the dispersion, the dope shows the characteristics of very lightly cross-linked high molecular weight polymer. In constrast, the dispersion shows the properties of an amorphorous polymer. The effects of chemical modification of the dispersion on the dynamic properties were also investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.473-474
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• 2010

This high pressure synchrotron X-ray diffraction study examined the change of bulk modulus of C-S-H(I), core material creating strength in alkali-activated slag cement as well as structural model of C-S-H, mainly attributed to Al-substitution for Si, which occurs at the bridging tetrahedral sites in dreierketten silicate chains in the nanostructure of C-S-H(I). This study presents that Al-substitution in C-S-H(I) does not affect the bulk modulus of C-S-H(I), which is surprising because many researchers have expected that Al-substitution should induce some critical change in mechanical properties of C-S-H(I).

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.24.1-24.1
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• 2010

In practical operation, the exposed surfaces may get dirty thus degrade the performance of devices. So the combination of self cleaning and antireflection is very desirable for use in outdoor photovoltaic and displaying devices, self cleaning windows and car windshields. For the purpose of self cleaning, the surface needs to be either superhydrophobic or superhydrophilic. However, in practice AR in the visible region and self cleaning are a pair of competitive properties. To satisfy the requirements for superhydrophobic or superhydrophilic surfaces, high surface roughness is required. But it usually cause severely light scattering. Photo-responsive coatings (TiO2, ZnO etc.) can lead to superhydrophilic. However, the refractive indices are high. Thus for porous structure, controlling pore size in the underwavelength scale to reduce the light scattering is very crucial for highly transparent and self cleaning antireflection coating. Herein, we demonstrate a simple method to make high performance broadband antireflection layer on the glass surface, by "carving" the surface by hot alkali solution. Etched glass has superhydrophilic surface. By chemical modification, it turns to superhydrophobic. Enhanced transparency (up to 97%) in a broad wavelength range was obtained by short time etching. Also antifogging effect has been demonstrated, which may offer advantage for devices working at high humidity environment or underwater. Compositional dependence of the properties was observed by comparing three different commercially available glasses.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.94-102
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• 2014

The physical and chemical properties of recycled fibers from mixed waste paper are more and more deteriorated because of unknown history of recycling times. In order to improve the mechanical properties of liner paper, the recycled fibers from wasted cotton clothes were used in papermaking process, and their applicabilities were evaluated in several points of fiber modification. Thus, two kinds of fiberizing methods from waste cotton clothes were considered by using rotary sandpaper and grinder mill. Finally, the rotary sandpaper method was relatively desirable in preserving longer fiber length and fibrillated fiber surface. The recycled cotton fibers by swelling treatment with NaOH and bleaching with reductive chemicals were mixed with OCC fibers, and the handsheets were prepared to basis weight of $80g/m^2$ and evaluated the mechanical properties of paper. The fibrous properties showed outstanding results in freeness and WRV improvements by alkali treatment and high brightness by reductive bleaching treatment. The physical and mechanical properties of sheet by mixing OCC fibers and recycled cotton fibers were also highly improved in tensile, burst strength and specially folding resistance.