• Elastomers and Composites
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• v.22 no.3
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• pp.204-212
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• 1987

The purpose of this study is to investigate the reinforced effect between MGF treated silane coupling agents and rubber matrix under the configuration chemical bonds, also the effect of triazine thiol compounds. For this study, vulcanizates were prepared with fifteen different compounding formulas. Their vulcanization characteristics, physical properties were examined by means of the ODR(Oscillating Dist Rheometer), the tensile tester, the benzene swelling test. The results of this study obtained are as follows: 1. In the ODR test, the MA vulcanizate was the fastest one in terms of having reached to optimum cure time($t_{90}$) and, with the same formula, when MGF vulcanizates, the shortest optimum cure times has appeared. 2. The SA, SC vulcanizates were the best the other in the physical properties such as 100%modulus, 200%modulus, 300%modulus, tensile strength. The SB vulcanizate, with higher density of crosslinking than other vulcanizates. The vulcanizates, which were filled with MGF treated with silane coupling agents we were the higher density of crosslinking than vulcanizates filled with MGF only. 3. In aging properties, the silica vulcanizates appeared to be better than the other vulcanizates. The aging Properties of treated MGF vulcanizates were similar to the silica vulcanizates. The(CR+APS+silica) and(CR+APS+MCF) were easily crosslinked by exposure to the air, and the physical properties have been improved.

• Composites Research
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• v.18 no.4
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• pp.27-34
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• 2005

Salt water spray and immersion tests were experimentally conducted for over 6 months to investigate the durability of glass fabric/phenolic composites under salt water environment. Mechanical properties such as tensile properties, flexural properties, and shear properties were evaluated and thermal analysis properties such as storage shear modulus, loss shear moduls, and tan 6 were obtained through a DMA. A change in chemical structures was analyzed through a FTIR. According to the results, mechanical properties and thermal analysis properties were sensitive to salt water environment and these properties began to degrade in increasing in exposure times. However, tensile and flexural moduli started to decrease and then slightly increase as increasing in exposure times due to plasticization and crosslinking in matrix as well as physical swelling in composites. Beyond a certain exposure times, these properties began to decrease as further increasing in exposure times. Also the shape and location of peaks in FTIR curves were insensitive to exposure times, but the intensity of peaks would be. finally we found that the durability of glass fabric/phenolic composites were affected on salt water immersion environment rather than salt water spray environment.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.124-128
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• 1999

The photochemistry of the derivatives of o-nitrobenzylcarboxyl esters or benzylsulfonyl derivatives has been well studied separately. But little attempt has been made to combine the fruits these two studies. Being photochemically active, benzylsulphonyl and intro groups should influence the reactivity of each other's, especially when the excited states are fully mixed due to the proximity of their location. The questions which should be clearly answered are; what kind of effect will be excerted to the other group, and whether these two functional groups are coupled in the course of the reaction. To answer the questions raised above, wer have synthesized two sulfonyl esters and four amides from the newly available starting material, 2-nitro-${\alpha}$-toluenesulfonyl chloride. The products identified from the exploratory solution photochemistry were cyclohexanol, phenol, cyclohexylamine, and sulfur dioxide. The results are not much different from the products originally anticipated. It has been temporarily concluded that there is little interaction between the benzyl sulfonyl group and ortho-nitro chromophore. The fact that a base (an amine) has been photochemically generated in solution photochemistry was further confirmed by and utilized in the solid phase quantitative photochemistry done on the film, so as to carry out the photochemical epoxide cure.

• Polymer(Korea)
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• v.34 no.3
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• pp.202-209
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• 2010

Aromatic copolyamides were prepared and their applicability to proton exchange membrane wasstudied. The copolymer contains thermally stable and mechanically strong poly(m-phenylene isophthalamide) segments, and easily processable and good film forming polysulfone segments. For the copolymer, amineterminated sulfonated ether sulfone monomer, m-phenylene diamine, and isophthaloyl chloride were reacted, and the obtained copolymer was transformed into crosslinkable prepolymer by the reaction with acryloyl chloride. The prepolymer was thermally cured and converted into proton exchange membranes for fuel cell application. Each reaction step and the molecular characteristics of precursor copolymers were monitored and confirmed by $^1H$ NMR, FTIR, and titration. The performance of the membranes was measured in terms of water uptake, proton conductivity, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with the increase of sulfonated ether sulfone segment content. Membrane containing 30 mol% sulfonic acid sulfone segment showed 1.57 meq/g IEC value. Water uptake was limited less than 44 wt% and the highest proton conductivity up to $3.93{\times}10^{-2}S/cm$ ($25^{\circ}C$, RH= 100%) was observed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.2
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• pp.82-89
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• 2007

Glass-ceramics were fabricated by heat-treating a glass at $700^{\circ}C$/10hr which was obtained by melting a glass frit mixed with $40{\sim}80 wt%$ EAF dust at $1300^{\circ}C$/1hr. Dependence of crystal phase and bonding state change upon a compositional change and heat treatment condition were studied and the results was connected to the toxic characterization leaching procedure (TCLP) test data to investigate a chemical durability of the specimens. Increasing dust in a glass shifted the peak around $1000cm^{-1}$ to the lower frequency which was composed of two vibration peaks for the nonbridging oxygen at $960cm^{-1}$ and the bridging oxygen at $1050{\sim}1060cm^{-1}$. Also, the $B_2O_3$ structure of boroxol ring changed to a tetrhedral-, trigonal- and di-borate with dust addition. The Fe-O peaks in the glass-ceramics were observed which is consitent with XRD results of spinel formation. The surface of glass after TCLP test was severely cracked while there was no cracks on a glass-ceramics after TCLP test so the chemical durability of the glass-ceramics is superior than that of glass. The leaching concentration of Fe for the glass-ceramics containing EAF dust 80 wt% is 1/15 times lower than that of glass. The Zn leaching concentration fur the glass-ceramics containing dust < 70 wt% was higher than that of glass but its trend was reversed for the specimen of dust content > 80 wt% which could be concluded as correlated with occurrence of willemite phase.

• Journal of the Korean Chemical Society
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• v.62 no.1
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• pp.24-29
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• 2018

Despite the great potential for the versatile applications in food industry and medical area, chitosan as a biocompatible cationic polysaccharide has suffered from the limited solubility under physiological condition. Herein, we demonstrated the electrostatic formation of chitosan-based polyplex particles, counterbalanced by polyacrylate as an anionic polyelectrolyte. The resulting polyplex exhibited pH- and composition-dependent changes in their surface charges as measured by zeta potential, which can be employed to provide the interparticle repulsive forces for enhanced colloidal stability in homogeneous solution. Subsequently, amide coupling between the acrylates and glucosamine residues of chitosan inside the polyplex further generated the hydrogel particles, which showed the temperature-sensitive swelling property. This aspect can be attributed to the partial formation of acryl amide residues, which have been generally known to possess the lower critical solution temperature (LCST).

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.81-87
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• 1999

Poly-acrylonitrile (PAN) based carbon fibers were stabilized under various tensions in the presence of air at about $200^{\circ}C$ and sequentially carbonized under some different gas environments in the range of 700 to $1500^{\circ}C$. The prepared carbon fibers were used for rechargeable lithium ion battery anode to investigate preparation parameters effects on electrochemical characteristics. It was found that the tension during stabilization, carbonization temperature and gas atmospheres affect the carbon fiber properties such as conductivity, mechanical strength, surface morphology and diffusion coefficient of lithium ion, which are closely related to the on electrolchemical properties as well as the charge/discharge characteristics.

• Journal of Sericultural and Entomological Science
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• v.20 no.1
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• pp.15-23
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• 1978

This studies have been carried out for several years to develop more better urea resin treating process on silk textiles which may be better crease resist without harming on the textile touch feeling. Specially, this paper payed attention to minimize the necessary formaldehyde content to be condensed with urea and created a new processing method which is named as Homo Metalic Urea Resin found to be better than urea resin process. The obtained results are as followings. 1. The prepared urea resin was found to be smell-less because of minimized formaldehyde content is the least than any other reports carried out before than this. 2. A new type of urea resin has been created by using uric 2incchloride and formaldehyde which is named as Homo Metalic Urea Resin. This processing method may carry both weighing process and urea resin process. 3. Crease resistance, stiffness and bulkiness were increased through such resin treats. Homo metalic urea resin process showed better results than the urea resin process. 4. Spun silk or low twisted silk have shown better crease resistance than raw silk or high twisted silk upon the both resin treats. 5. Both treat methods were found to be good economical feasibility upon the silk finishing process. 6. Tenacity and elongation of silk fibers were found to decrease some what because of grafting or weighing results. 7. Wooly silk has been also created with specific urea resin process. Such silk could be obtained by formaldehyde gas treat with urea soaken silk in a chamber, which induced to form scale on the surface of silk fibers.

• KSBB Journal
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• v.11 no.5
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• pp.606-612
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• 1996

A specific ammino auid in a mixture can be crystallized inside an ion exchange column when displacer concentration is high enough to concentrate the amino acid in a pure band beyond its solubility limit. Glutamic acid formpd a discrete crystal layer in a cation exchanger column by operating displacement development mode and using a high concentration of displacer NaOH. The glutamic acid crystal formed was eluded from the column with the effluent stream and collected in a fraction collector. When 1.0 M of NaOH was used as a displacer, more than 60% of the loaded glutamic acid was recovered as crystal. The continuous crystallization and dissolution of crystal occurred, resulting in apparent movement of the crystal along the column without clogging or pressure increase. NaOH was proved a better displacer than NaCl because hydroxide ions neutralized hydrogen ions released from the resin and thus reduced the number of hydrogen ion competing with sodium ion for re-adsorption. The displacement development process coupled with crystallization provided higher concentration and recovery of glutamic acrid than conventional chromatography.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.300-306
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• 1989

Physico-chemical changes caused by salting Korean radish cubes (for Kakdugi) with sodium chloride solution were investigated. Two-centimter cubes of Korean radish were soaked in saline solution of 5, 10, 15, 20 and 25 percent concentration. Optimum salinity, 3% as determined by taste, was reached in six hours at 5% strength, two hours in 10%, one hour at 15% and within one hour at concentration of 15% plus. Radish cubes salted in 5, 10. 15, 20 and 25% sodium chloride solution in a cube/solution weight ratio of 1:1 decreased in volume from 7.6 to 11.2% after one hour, and from 11.2 to 17.9% after six hours. Decrease in moisture content was from 83.0 to 75.9% in one hour and from 74.5 to 68.5% after six hours. $Potassium\;ion(K^+)$, $calcium\;ion(Ca^{2+})$ and $magnesium\;ion(Mg^{2+})$ content was significantly decreased by salting, but $sodium\;ion(Na^+)$ content greatly increased. In addition, salting caused firmness of the cubes to decrease, and cell shapes to shrink by plasmolysis.