• Journal of Integrative Natural Science
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• v.7 no.1
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• pp.5-10
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• 2014

A study that copolymerized Ag nanoparticle and furfuryl isocyanate with the crosslinking agent EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), MA (methacrylic acid) and the initiating agent AIBN (azobisisobutyronitrile) is presented. Measurement of the physical characteristics of the produced macromolecule showed that the water content is 32.08~32.67%, refractive index 1.446~1.448, visible light transparency 83.2~67.6%, contact angle $68.2{\sim}83.5^{\circ}$ and tensile strength 0.541~0.755 kgf. It is also demonstrated that the addition of Ag nanoparticles is associated with the reduction of UV-B transmittance and increase in tensile strength. The results show that the produced copolymer can be used as a material for ophthalmic lenses with durability and UV-blocking properties.

• Polymer(Korea)
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• v.27 no.3
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• pp.195-200
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• 2003

Alginate is a natural ionic polymer including numerous anionic groups and can be actuated by the ionic group under the electric field. The crosslinked alginate films were fabricated with CaCl$_2$. The thermal, mechanical and electroresponse properties of the films were investigated by thermogravimetric analysis, tensile and bending tests. The initial degradation and tensile strength increased according to the degree of crosslinking. Also, the swelling ratio of the films increased with decreasing degree of crosslinking and increasing pH due to free volume and electrostatic repulsion. The films actuated by an electric stimulus exhibited gentle and flexible action like a pendulum. In the electric field, the electric stimuli such as the applied voltage, ionic strength and kind of electrolyte solution had an effect on the electroresponse of the films. Alginate films with 5 wt% crosslinking agent showed the highest bending angle and reversible bending behavior. When the ionic strength of NaCl and KCl electrolyte solution was 0.1 M, the films showed the highest electroresponse. The bending behavior of the films increased with the applied voltage.

• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.263-268
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• 2009

Superporous Hydrogels (SPHs) have been extensively investigated for various biomedical applications due to their fast swelling and superabsorbent properties. In this study, glycol chitosan that is one of most abundant natural polymers was used as a cross-linking agent instead of bisacrylamide (BIS), which is a broadly used crosslinking agent for preparation of SPHs. Glycol chitosan was modified to have reactive vinyl groups by chemical conjugation with glycidyl methacrylate (GMA). The vinyl group-containing glycol chitosan (GC-GMA) was characterized by FT-IR and $^1H$-NMR measurements. SPHs have been prepared in various synthetic conditions to establish the optimum synthetic process for making superporous structure, where the inner pores are interconnected to each other to form a open channel structure. Various SPHs with different GC-GMA contents have been successfully prepared and have been observed to show faster swelling properties than other conventional SPHs. From the study on the swelling behavior of SPHs, the GC-GMA content is considered to be an important factor for controlling their swelling properties.

• Archives of Pharmacal Research
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• v.19 no.3
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• pp.191-196
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• 1996

Bizelesin is a promising novel anticancer agent which is known to alkylate N3 of adenine to induce DNA interstrand cross-links (ISC) with in $5^I-TAATTA\; and\; 5^I-TAAAAAA$. We have investigated the base specificity for DNA ISC induced by bizelesin using oligomers containing the cross-linkable sequence $5^I-TAATTA\; and\; 5^I-TAAAAAA$. in which "N" was either A, C, G, or T. An analysis of denaturing polyacrylamide gel showed that bizelesin is able to induce DNA ISC in the duplex oligomer containing sequences $5^I-TAATTA\; and\; 5^I-TAAAAAA$. The formation of interstrand crosslinking did not occur in the sequences $5^I-TAATTA\; and\; 5^I-TAAAAAA$. DNA strand cleavage assay to determine the cross-linking site within $5^I-TAATTA$sequence showed that bizelesin alkylates guanine. These results demonstrate that bizelesin is able to induce DNA ISC at guanine but not at cytosine or thymine. In addition, guanine adducts have been found to be susceptible to DNA strand cleavage by exposure to hot piperidine. The extent of DNA strand cleavage, however, was not 100% efficient in either neutral pH buffer or hot piperidine.

• Journal of Integrative Natural Science
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• v.11 no.1
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• pp.1-8
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• 2018

HEMA, AA, MMA, and EGDMA as crosslinking agent and AIBN as an initiator, and 2,4-dihydroxybenzophenone, 2-ethylhexyl-trans-4-methoxy-cinnamate, 2-hydroxy-4-(methacryloyloxy)benzophenone as additives at 0.1-1.0% ratios were used to manufacture hydrophilic ophthalmic lenses through thermal polymerization before their physical properties were measured. The results showed that the samples containing of 2,4-dihydroxybenzophenone and 2-ethylhexyl-trans-4-methoxy-cinnamate resulted in a decrease of the UV blocking performance after high-pressure sterilization whereas the sample containing 2-hydroxy-4-(methacryloyloxy)benzophenone showed no change in the UV blocking performance. It is judged that this is induced by presence or absence of an acyl functional group in benzophenone.

• Fashion & Textile Research Journal
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• v.10 no.4
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• pp.544-551
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• 2008

In this study, the colorants of Amur cork tree were extracted with boiling water. Chitosan crosslinked cotton fabrics have been dyed with aqueous extract of Amur cork tree and their dyeabilities on the fabrics were studied. Additionally the fastness to washing and light were also investigated. Cotton fabrics were treated with a crosslinking agent epichlorohydrin in the presence of chitosan to provide the cotton fabrics the dyeing properties of natural dye(Amur cork tree) by the chemical linking of chitosan to the cellulose structure. This process was applied by means of the conventional mercerizing process. The chitosan finishing and durable press finishing of the cotton fabrics occurred simultaneously in the mercerization bath. On the surface color change, the fabric of no-chitosan finished and no-mordanted has greenish yellow. The more crosslinked chitosan on cotton fabrics has the more turned down greenish on the surface color, as increasing the concentration of chitosan, greenish color turn down to the yellow close the 90o hue angle. In all sorts of fabrics, dyeability(K/S) is slightly affected by the number of manufacturing process and the concentration of chitosan. But only mercerized cotton fabric has higher dyeability (K/S) than mordant treated cotton fabrics. Wash fastness has little different results by each condition, but almost similar values. Light fastness was improved with chitosan treatment on cotton fabric.

• Fashion & Textile Research Journal
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• v.12 no.3
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• pp.381-388
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• 2010

The purpose of this study was investigate the dyeing property on chitosan crosslinked cotton fabric with cochineal at variable conditions. Chitosan crosslinked cotton fabrics were manufactured by crosslinking agent epichlorohydrin in the presence of chitosan. Chitosan crosslinked cotton fabrics dyed using cochineal were post-mordanted using Al, Fe and Cu. The dyeability(K/S) of chitosan crosslinked cotton fabrics were measured by computer color matching. Additionally the fastness to washing and light were also investigated. The dye-uptake of chitosan crosslinked cotton fabrics increased with the dyeing time. The saturated dyeing time was about 20minutes at $60^{\circ}C$. The dyeability(K/S) was remarkably increased with increasing content of crosslinked chitosan because of having a amine group of chitosan. Chitosan crosslinked cotton fabrics were dyed yellowish red by non and Fe mordanting, blueish red by Al and Cu mordanting, respectively. The washing and light fastness were increased by mordanting, especially Cu and Fe mordanting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1678-1686
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• 2021

In this study, we prepared phosphorous flame-retarding coating solutions by mixing triphosphate (3 phosphonate), phytic acid (6 phosphonate), or ammonium polyphosphate (10 phosphonate) with boric acid as a crosslinking agent and acryl resin binder. Prepared phosphorous flame-retarding coating solutions were coated onto non-woven fabrics, respectively, to obtain high flame-retarding effects. These prepared flame-retardant non-woven fabrics were evaluated using smoke density standard test (ASTM E662), limit oxygen index standard test (ISO E622), and vertical burning standard test (UL 94). Their flame-retarding effects were affected by the number of phosphonate groups. Regardless of natural or synthetic binder resins, their effects showed the following order: ammonium polyphosphate > phytic acid > triphosphate. Natural hydrocarbon compounds were also examined to determine the possible retardancy of binder resins. Results showed that natural hydrocarbon binder resins could be used for preparing fire-retardant nonwoven fabrics.

• Elastomers and Composites
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• v.47 no.1
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• pp.23-29
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. As silane (TESPT) concentration increased from 2 to 12% (2, 4, 6, 8, 10, 12%), the ${\alpha}_F$ value increased at the same silica concentration (10, 20, 30, and 40 phr). It seemed the sulfur atoms in TESPT acted as a crosslinking agent in the compound. As silica concentration increased from 10 to 40 phr, the ${\alpha}_F$ value increased at the same silane concentration due to increased silica-silica interaction.