• Elastomers and Composites
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• v.47 no.1
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• pp.54-64
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• 2012

Acrylonitrile was introduced in the emulsion SBR to increase compatibility between silica and rubber. AN-SBR/silica compounds showed faster vulcanization time and higher delta torque values than SBR 1721/silica compounds because interaction between nitrile group of AN-SBR and silanol group on the silica surface could make hydrogen bond that prevented adsorption of the accelerator on the silica surface, which improved the vulcanization reaction efficiency and enhanced the degree of crosslinking. AN-SBR/silica compound showed higher values in minimum torque than SBR 1721/silica compound during the vulcanization because AN-SBR has higher molecular weight than SBR 1721 in the raw material. When PEG was added to the SBR 1721 and AN-SBR compounds, vulcanization time was faster than SBR 1721 and AN-SBR compounds without PEG because PEG has a large number of ether linkages which show high compatibility with silanol group on the silica surface that prevented the adsorption of the accelerator and the ingredients on the silica surface, which improved the vulcanization reaction efficiency. In the mechanical properties, AN-SBR compounds showed higher modulus values at 100%, 300% than SBR 1721 compounds because interaction between nitrile group of AN-SBR and silanol group on the silica surface enhanced the degree of crosslinking. In the dynamic properties, AN-SBR compounds showed lower tan ${\delta}$ values at $0^{\circ}C$ than SBR 1721 compounds in accordance with the $T_g$ values. AN-SBR compounds showed lower tan ${\delta}$ values at $60^{\circ}C$ than SBR 1721 compounds because interaction between acrylonitrile and silica caused strong filler-rubber interaction that induced low energy dissipation by the filler-filler interaction.

• Membrane Journal
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• v.18 no.3
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• pp.234-240
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• 2008

This work demonstrates the preparation of proton conducting crosslinked polymer electrolyte membranes by blending polystrene-b-poly(hydroxyethyl acrylate) (PS-b-PHEA) and poly(vinyl alcohol) (PVA) at 1 : 1 wt ratio. The PHEA block of the diblock copolymer was crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of membrane and -COOH of SA, as confirmed by FT-IR spectroscopy. Ion exchange capacity (IEC) continuously increased from 0.14 to 0.91 meq/g with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. In contrast, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane also exhibited a maximum proton conductivity of 0.024 S/cm at 20.0 wt% of SA concentration. The maximum behavior of water uptake and proton conductivity is considered to be due to competitive effect between the increase of ionic sites and the crosslinking reaction according to the SA concentration.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.802-812
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• 2016

Silicone foam is very useful as flame resistant material for many industrial areas such as high performance gasketing, thermal shielding, vibration mounts, and press pads. A silicone foam was prepared through simultaneous crosslinking and foaming by hydrogen condensation reaction of a vinyl-containing polysiloxane (V-silicone) and a hydroxyl-containing polysiloxane (OH-silicone) with hydride containing polysiloxane (H-silicone) in the presence of platinum catalyst and imorganic filler at room temperature. This is more convenient process for silicone foam manufacturing than the conventional separated crosslinking and foaming systems. Funtionalized silicones we used in this experiment were consisted with a V-silicone containing 1,0 meq/g of vinyl groups and a viscosity of 20 Pa-s, an OH-silicone with 0.4 meq/g of hydroxyl groups and a viscosity from 50 Pa-s, and an H-silicone containing 7.5 meq/g of hydride groups and a viscosity of 0.06 Pa.s. The effects of compositions of functionalized silicones and additives, such as catalyst and filler on the structure and mechanical properties of silicone foam were studied. 0.5 wt% of Pt catalyst was enough to accelerate the foaming rate of silicone resins. The addition of OH-silicone with lower viscosity accelerates the initial foaming rate and decreases the foam density, but the addition of V-silicone with lower viscosity reduces the tensile strength as well as the elongation. The final foam density, tensile strength, and elogation of silicone foam prepared under the SF-3 condition increase maximum to $0.58g/cm^3$, $3,51kg_f/cm^2$, and 176 %, repectively. We found out the filler alumina also played an important role to improve the mechanical properties of silicone foams in our foaming system.

• Journal of the Korean Applied Science and Technology
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• v.20 no.1
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• pp.8-19
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• 2003

Environmental friendly acrylics/urea high-solid paints (BEHCU) were prepared through the curing reaction of acrylics resin(BEHC) containing 70wt% of solids content and butylated urea curing agent. BEHC was synthesized by addition copolymerization of caprolactone acrylate(CLA), 2-hydroxypropyl methacrylate(2-HPMA), ethyl methacrylate, and n-butyl acrylate. The addition polymerization of these monomers, especially including flexible CLA monomer and 2-HPMA monomer with OH funtional group, under appropriate reaction conditions resulted in polymers with controlled glass transition temperature($T_g$) and crosslinking density. The molecular weight($M_w$) of these polymers(BEHCs) was 2940${\sim}$3240 and polydispersity ($M_w/M_n$) was in the range of 1.61${\sim}$1.72. The viscosity and the molecular weight of these acrylic resins increased with increasing $T_g$. The coated films were prepared using curing reaction between BEHC resin and butylated urea curing agent at 100$^{\circ}C$ for 30 minutes. Our experimental resulted showed that enhancement of the coating properties such as adhesion, flexibility, impact resistance, water resistance, and abrasion resistance could be expected through introducing CLA component in acrylic resin for the high-solid content acrylics/urea coatings.

• The Journal of Korean Physical Therapy
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• v.12 no.2
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• pp.191-201
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• 2000

This study was investigated the effects of a direct current and ultrasound on transdermal transport of dexamethasone into the rabbits which had contusion in the thigh. Each group was treated under the tallowing conditions. 1. EXP group I : $10\%$ dexamethasone ointment and ultrasound 2. EXP group II : $1\%$aqueous solution of dexamethasone and iontophoresis 3. EXP group III : the application of $10\%$ dexamethasone ointment 4. Control group : No treatment The degree of anti-inflammation was evaluated by the naked eye, the change in girth of thigh, and a light microscope. The results were as follows. 1.8y the naked eye. an inflammation sign was seen in all groups and especially. symptoms of redness. heat swelling were prominent in EXP group I. 2. In comparision in the change of girth of thigh, only EXP group II showed no significant change. Therefore, it meant that there was effective anti-inflammatory reaction in EXP group II. 3. The infiltration of inflammation cells, the degree of swelling, and the degree of crosslinking of connective tissues were evaluated with a light microscope. As a result, EXP group II showed the most effective anti-inflammatory reaction. And, in order of EXP group III, control group, the effect of anti-inflammation reaction was decreased. 4. EXP group I showed more intensive inflammation than control group.

• Polymer(Korea)
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• v.35 no.5
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• pp.488-492
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• 2011

Three isocyanatopropyldimethoxysilylpolydimethylsiloxanes(IDMSi-PDMS) were synthesised from the reaction of isocyanatopropyltrimethoxysilane with monohydroxyl group termainated PDMS having different molecular weight($M_n$=5000, 10000, and 20000). Then PDMS modified polyurethane hybrid elastomer(PSMPH) were prepared from the reaction of IDMSi-PDMS with ${\alpha}$, ${\omega}$-hydroxyl group terminated polyurethane. PSMPH sealant was prepared by compounding PSMPH elastomer with additives such as plasticizer, adhesion promoter, crosslinking agent, vicosity increasing agent, inorganic filler, and catalyst at room temperature under nitrogen atmosphere. The methoxy group in the PSMPH sealant should be crosslinked with the hydroxyl group in the building stone or moisture by typical sol-gel reaction. The adhesive strength of the sealant having PDMS of $M_n$=5000 showed 40.28 kg of maxium load and 20.14 kg of break load. The shrinkage rate of the sealant having PDMS of $M_n$=20000 was 5.7% as the best result. Also, their skin over time, slump, oil content after 8 days under oil soaked paper and alkaline resistance characteristics show good results.

• Polymer(Korea)
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• v.29 no.1
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• pp.1-7
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• 2005

Interpenetrating polymer network (PN) is a mixture of network polymers. The characteristics of IPN material is the control of morphology during the IPN synthesis. By controlling the relative kinetics of chemical reaction (as well as gellation) and phase separation, the morphology of IPN can be controlled to obtain materials with nano-scale domain and also the co-continuous phase. Other important advantage is the fact that the morphology is permanent due to the presence of the physical interlocking between the networks. The combination of hydrophilic polyurethane and hydrophobic polystyrene in IPN form provides enhanced blood compatibility due to the co-existence of the hydrophilic and hydrophobic domains in nano-scale on the surface. The reaction temperature, reaction pressure and the degree of crosslinking were varied during the IPN synthesis and the morphology and blood compatibility of the resulting IPN materials were studied.

• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.163-167
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• 2021

In the present work, we studied a method for the synthesis of uniform gold-peptide hierarchical superstructures using tyrosine rich peptide, Tyr-Tyr-Leu-Tyr-Tyr (YYLYY). Peptide nanoparticles self-assembled by dityrosine bonds were synthesized through the photo-crosslinking reaction of the peptide, and gold-peptide hybrid nanoparticles were synthesized using biomineralization properties of tyrosine in a green synthetic manner. The synthesized gold-peptide hybrid nanoparticles were then characterized by transmission electron microscopy, scanning electron microscopy, dynamic light scattering, UV-vis spectroscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, the catalytic activity of gold-peptide hybrid nanoparticles was confirmed by the reduction reaction of methylene blue where the catalytic reaction rate constant was 13.4 × 10-3 s-1.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.406-414
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• 2010

A novel polyacrylamide grafted hydrous ferric oxide adsorbent composite has been synthesized by using glow discharge electrolysis plasma. To optimize the synthesis conditions, the following parameters were examined in detail: applied power, discharge time, post polymerization temperature, post polymerization time, amount of crosslinking agent and hydrous ferric oxide gel added and so on. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The removal percentage of the adsorbent in Pb(II) solution was examined and the data obtained showed that the adsorbent composite has a high capacity for lead ion. For the use in wastewater treatment, the thermodynamic and kinetic of Pb(II)-capture were also studied. Results indicated that the adsorption reaction was a spontaneous and an endothermic process, and it seems to be obeyed a pseudo-secondorder rate model. Moreover, the adsorption isotherm of Pb(II)-capture is following the Langmuir and Freundlich isotherm models.

• Journal of environmental and Sanitary engineering
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• v.21 no.4 s.62
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• pp.49-60
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• 2006

The ion exchange resins have been synthesized from chlormethyl styrene - 1,4 - divinylbenzene(DVB) with 1%, 2%, 4% and 8%-crosslinking and 1-aza-18-crown-6 macrocyclic ligand by copolymerization method. Content of chlorine in styrene-DVB copolymer was decreased as crosslink increased and it is because as crosslink increased 1%, 2%, 4% and 8% DVB content increased and crosslink density increased and cavity was reduced. Functional group of resin almost disappeared as C-C1 peak around $700cm^{-1}$ was substituted with 1-aza-18-C-6 macrocyclic ligand and new peak of C-N around $1020cm^{-1}$ appeared, so it was confirmed that styrene-DVB copolymer and ligand were compounded. As crosslink increased in the analysis of element contents, it resulted in the reduction of nitrogen content and it is because as crosslink increased, it led to the reduction of chlorine content in the process of substitution reaction and it affected macrocyclic ligand substituted. Thermo analysis curve of functional synthetic resin decomposed three part of 1-aza-18-C-6, styrene, and DVB. Form of functional synthetic resin showed distortion of its particles as macrocyclic ligand was introduced to styrene-DVB copolymer and hydrogen of ligand caused substitution with chlorine element of styrene molecule.