• Proceedings of the Korean Environmental Sciences Society Conference
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• 2017.10a
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• pp.213-213
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• 2017

• Journal of Pharmaceutical Investigation
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• v.40 no.3
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• pp.167-173
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• 2010

Repeated oral administration of hydrochlorothiazide, a loop diuretic, due to transient high blood levels, may cause adverse effects such as gastric disturbance, nausea, high blood sugar, and hyper lipidemia. Transdermal administration could avoid some of these systemic side effects and gastric disorders. We have developed a matrix using ethylene-vinyl acetate (EVA), a heat-processible and flexible material, for transdermal delivery of hydrochlorothiazide. Drug solubility was highest at 40% PEG-400 volume fraction. Drug release increased as concentration increased with a linear relationship between the release rate and the square root of loading dose. Increasing temperature increased drug release from the EVA matrix. The activation energy, measured from the slope of log P versus 1000/T, was 11.9 kcal/mol for a 2.5% loading dose from EVA matrix. Diethyl phthalate had the highest plasticizing effects on the release of hydrochlorothiazide. To increase the skin permeation of hydrochlorothiazide from the EVA matrix, enhancers such as the saturated fatty acids, the unsaturated fatty acids, and the non-ionic surfactants were added to the EVA matrix, and skin permeation was evaluated using a modified Keshary-Chien diffusion cell fitted with intact excised rat skin. Polyoxyethylene 23-lauryl ether showed the highest enhancing effects. In conclusion, transdermal delivery of hydrochlorothiazide could be improved from an EVA matrix containing plasticizer and permeation enhancer.

• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.281-289
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• 1996

In our previous work, we have studied the effect of lactose and sodium alginate (SA) on the rate of release of 5-fluorouracil (5-FU) from ethylene-vinyl acetate (EVA) matrix. These hydrophilic additives promoted the rate of 5-FU release and the increase in rate was larger when SA was used. Both additives showed better ability to increase the rate than 5-FU itself. In this paper, we extended our study to another hydrophilic additive, Carbopol 940 (CP). Compared to SA or lactose, CP increased the rate of 5-FU release markedly. Release rate increased as the loading amount and the pH of the release medium increased. After release experiment, matrix volume increased up to 15 times of that before release experiment, depending on the amount of CP dispersed in the matrix and the pH of the release medium. On the other hand, the volume of the matrix containing lactose or SA decreased. The weight changes of the dry matrix before and after release experiment imply that CP is not released out of the matrix, to the contrary of lactose and SA. Scanning electron microscope study clearly showed that large cavities and pores are generated on the surface and the inside of the matrix. These results indicate that the mechanism by which CP increases the release rate is quite different from that of monomeric additives such as lactose or SA.

• Resources Recycling
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• v.20 no.6
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• pp.50-55
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• 2011

Using ultrasonic irradiation, the separation and recovery of PV cell, made of silicon wafer, from PV module was carried out through selective decomposition of EVA used as an interlaminated binder. The ultrasonic cleaner of bath-type (Output: 130 W, Frequency: 40 kHz) was used as an ultrasonic apparatus in this research. With the fixed distance of 2 cm, from ultrasonic generator to PV cell, the experiment of EVA decomposition was performed in various organic solvents such as Toluene, Trichloroethylene, O-dichlorobenzene, Benzene. And also their concentrations and temperature was changed to survey the optimum conditions. However EVA can be decomposed perfectly at $55^{\circ}C$ within 160 min in 5 M of all kinds of solvent, PV cell may be recovered with being damaged or broken severely. This damage may be resulted from the swelling of EVA in the process of decomposition. Whereas, at the condition of 5 M at $65^{\circ}C$, PV cell can be recovered with the state of minor damage or crack. This implies that the decomposition rate of EVA increases with an increase of temperature, thereby EVA can be decomposed before the swelling of EVA layer. Conclusively, it is possible for PV cell to be recovered within 40 min, at $65^{\circ}C$ in 5 M, with less damage.

• Journal of Korea Foresty Energy
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• v.18 no.2
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• pp.55-61
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• 1999

This study was carried out to investigate the influence of viscoelastic properties(or chemical composition) of a series of ethylen-viny1 acetate copolymers on impact noise and vibration damping of wood/polymer/wood sandwich composites. The impact noise and vibration damping of composites were very sensitive to the state of molecular motion of polymer. The noise and vibration damping of composites were maximum when the polymer was under the glass transition(vinylacetate 55~75%) at the test-temperature, and minimum rubbery state(vinyl-acetate 47~20%) or glassy state(vinylacetate 100~87%). The polymer under glass transition reduced the impact noise by 6~12 dB.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.427-434
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• 1994

The retention behaviors of poly(ethylene-co-vinyl acetate)s have been studied by thermal field-flow fractionation(ThFFF) with respect to effective separation and characterization of thermal diffusion coefficients($D_{\tau}$) as one of the physicochemical properties of polymers. The eight copolymers are different in vinyl acetate composition ranging from 25% to 70% and in molecular weight ranging from 110,000 to 285,000. The carrier solvents are THF, toluene and chlorobenzene which have different viscosities and thermal conductivities. It is shown that the retention of a copolymer is dependent on the type of the carrier, the molecular weight and chemical composition of the copolymer. The results show that the retention of a copolymer increases when either vinyl acetate composition or the molecular weight increase. $D_{\tau}$ values measured by experiments vary from 1.36∼5.97 $\cm^2/(s.K)$ depending on the copolymer composition and the type of the carrier solvent. These values increase $(r^2{\geq}0.928)$ with increase of weight % of vinyl acetate. THF is found to be the proper carrier solvent for separation of copolymers employed in this study due to the fact that a $D_{\tau}$ value greatly changes with variation of copolymer composition. From the above results, ThFFF can be used for separation of copolymers with similar molecular sizes but different compositions.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.117-124
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• 2011

We demonstrate a new surface modification of high-voltage lithium cobalt oxide ($LiCoO_2$) cathode active materials for lithium-ion batteries. This approach is based on exploitation of a polarity-tuned gel polymer electrolyte (GPE) coating. Herein, two contrast polymers having different polarity are chosen: polyimide (PI) synthesized from thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid (as a polar GPE) and ethylene-vinyl acetate copolymer (EVA) containing 12 wt% vinyl acetate repeating unit (as a less polar GPE). The strong affinity of polyamic acid for $LiCoO_2$ allows the resulting PI coating layer to present a highly-continuous surface film of nanometer thickness. On the other hand, the less polar EVA coating layer is poorly deposited onto the $LiCoO_2$, resulting in a locally agglomerated morphology with relatively high thickness. Based on the characterization of GPE coating layers, their structural difference on the electrochemical performance and thermal stability of high-voltage (herein, 4.4 V) $LiCoO_2$ is thoroughly investigated. In comparison to the EVA coating layer, the PI coating layer is effective in preventing the direct exposure of $LiCoO_2$ to liquid electrolyte, which thus plays a viable role in improving the high-voltage cell performance and mitigating the interfacial exothermic reaction between the charged $LiCoO_2$ and liquid electrolytes.

• Macromolecular Research
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• v.11 no.4
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• pp.260-266
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• 2003

Ethylene vinyl acetate (EVA)/clay nanocomposites were synthesized by blending a solution of ethylene vinyl acetate copolymer containing 12% vinyl acetate abbreviated as EVA-12 in toluene and dispersion of dodecyl ammonium ion intercalated montmorillonite (l2Me-MMT) in N,N-dimethyl acetamide (DMAc). X-ray patterns of sodium montmorillonite ($Na^+$-MMT) and 12Me-MMT exhibited $d_{001}$ peak at $2{\theta}=7.4^{\circ}$ and $2{\theta}=5.6^{\circ}$ respectively; that is, the interlayer spacing of MMT increased by about 0.39 nm due to intercalation of dodecyl ammonium ions. The XRD trace of EVA showed no peak in the angular range of $3-10^{\circ}(2{\theta})$. In the XRD patterns of EVA/clay hybrids with clay content up to 6 wt% the basal reflection peak of 12Me-MMT was absent. leading to the formation of delaminated configuration of the composites. When the 12Me-MMT content was 8 wt% in the EVA-12 matrix, the hybrid revealed a peak at about $2{\theta}=5.6^{\circ}$, owing to the aggregation of aluminosilicate layers. Transmission electron microscopic photograph exhibited that an average size of 12-15 nm clay layers were randomly and homogeneously dispersed in the polymer matrix, which led to the formation of nanocomposite with delaminated configuration. The formation of delaminated nanocomposites was manifested through the enhancement of mechanical properties and thermal stability, e.g. tensile strength of an hybrid containing only 2 wt% 12Me-MMT was enhanced by about 36% as compared with neat EVA-12.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1667-1670
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• 1999

In this paper, We are studied the electrical properties of thin film mixed with LLDPE and EVA, and the specimen is selected as Low Linear Density Polyethylene and Ethylene Vinyl Acetate produced by mixture ratio of 50:50, 60:40, 70:30 and 80:20. (thickness $100[{\mu}m],\;70[{\mu}m],\;50[{\mu}m],\;30[{\mu}m]$). As the electrical properties. one is electrical conduction characteristics of the due to mixture ratio of linear low density polyethylene (LLDPE) and ethylene vinyl acetate(EVA), the other is AC breakdown of specimens due to variation of the thickness. From the result of XRD, it is confirmed that specimen of 80 : 20 and virgin LLDPE have high peaks at $2\theta=21.4[^{\circ}]$ and the peak by the contribution of amorphous at $2{\theta}=19.5[^{\circ}]$ is constant with no relation to mixture ratio, but virgin EVA is somewhat lower.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.786-794
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• 1994

The strength and durability of polymer-cement mortars were investigated. The specimens of polymer-cement mortar were prepared by using styrene-butadiene rubber(SBR) latex, ethylene-vinyl acetate(EVA) emulsion and polyacrylic ester(PAE) emulsion with various polymer-cement ratios(5, 10, 15, 20wt%). For the evaluation of durability of polymer-cement mortars, freezing-thawing, acid resistance and heat resistance tests were conducted. With an increase of polymer-cement ratio, the frost resistance of polymer-cement mortars was greatly improved, but acid and heat resistance were deteriorated. The compressive and flexural strengths of SBR polymer-cement mortars were improved with an increase of polymer-cement ratio, whereas those of EVA and PAE polymer-cement mortars reached maximum value at polymer-cement ratio of 10wt%.