• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1297-1303
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• 2012

In this paper, the standard procedures for measuring the moisture sorption properties of thin polymeric materials such as polyethylene terephthalate (PET) by using the thermo-gravimetric method to characterize the moisture diffusion in the polymer are presented, and the sorption properties are quantified. The moisture diffusivity and solubility are characterized to investigate the effect of temperature and humidity on the moisture sorption properties according to the Arrhenius equation. The validation of the obtained sorption properties using thermogravimetry is discussed with the measured permeability based on Fickian diffusion. The nonlinear behavior of the concentration dependent moisture diffusion is investigated experimentally, and the nonlinearity is characterized numerically for the case of having an interface with an inorganic material such as a metal. The Fickian/Non-Fickian model based on the obtained moisture sorption properties is compared and discussed.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2696-2698
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• 2004

Iontophoresis를 이용한 경피전달용 약물 패치를 제작하기 위해 고분자의 종류, 전류크기, 시간에 따른 약물방출 결과를 발표한다. 고분자 Hydroxy Propyl Methyl Cellulose(HPMC), Hydroxy Propyl Cellulose(HPC), Hydroxy Ethyl Cellulose(HEC)에 각각 국소마취제-Lidocaine을 넣어 시료를 제작하였다. 약물 방출은 Drug Delivery Cell(DDC)위에 Ag/AgCl 전극 (anode), Pt wire 전극(cathode)을 각각 설치하여 전압인가에 따른 이온 유동으로부터 시간에 따른 전압/전류변화 및 약물농도를 고찰하였다. 전압 15V 인가 시 고분자 막과 전해질 사이에 흐르는 전류 1.0mA는 15분간 유지되지만, Ag/AgCl 전극의 산화작용으로 인해 전류는 서서히 감소하며 26분 후 거의 흐르지 않았다. 따라서 안정적인 전류로 유지되는 시간을 15분으로 최적화하였다. 고분자 중 HPMC 막을 사용하여 약물방출 실험을 한 경우 UV 분석결과 파장 262.26nm에서 최대 흡광도 0.238이었고, 가장 높은 약물농도가 나타났다. 이러한 HPMC의 약물방출 실험결과 비교적 높은 전류 1.0mA일 때 약물 방출량이 많았고, 동일한 전류 0.4mA를 장시간 흐르게 하였을 경우, 농도가 축적되므로 치료 가능한 안정적인 특성임을 확인하였다.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.255-259
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• 2006

Ultrafine fibers having approximately 800 nm diameter were prepared by an electrospinning method from cellulose acetate. Cellulose acetate dissolved in acetone solutions were electrospun at various conditions. The cellulose polymer solutions of various concentrations were applied under different voltages, flow rates, and tip-to-collector distances (TCD). The diameter of fibers depended on the electrospinning parameters such as its viscosity. The fibers were not formed from the polymer solutions less than 12.0 cP viscosity. The minimum diameter was 800 nm at 12.5 wt% of polymer concentration, 12 kV of voltage, $100{\mu}L/min$ of flow rate, and 7.5 cm TCD.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.147-151
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• 2014

In many polymer processing operations, the diffusion of small molecules in polymeric materials plays an important role. The fundamental physical property required to design and optimize processing operations is the mutual diffusion coefficient. To investigate the transport properties of polymer/solvent systems at infinite dilution, capillary column inverse gas chromatography (CCIGC) is often employed. In this study, diffusion and partition coefficients of cyclic solvents in styrene/butadiene/styrene (SBS) block copolymer were measured over a wide temperature range using the CCIGC technique.

• Polymer(Korea)
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• v.29 no.4
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• pp.392-398
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• 2005

Self-assembled multilayer thin films of poly(ethylene-alt-maleic anhydride) (PEMAh) and poly(4-vinyl pyridine) (P4VP) were fabricated by layer-by-layer (LbL) sequential adsorption. Fourier transform infrared (FT-IR) spectroscopic analysis of the self-assembled PEMAh/P4VP multilayer films confirms that the driving forces for the multilayer buildup are the intermolecular hydrogen bonding and electrostatic interactions. The linear increase of absorption peak of P4VP at 256 nm with increasing number of PEMAh/P4VP bilayers indicates that the multilayer buildup is an uniform assembling process. We also investigate the effects of polyelectrolyte concenhation variation of the dipping solution and pH variation of the PEMAh solution on the multilayer film formation. Thickness. adsorbed polyelectrolyte mass and surface roughness of the multilayer films were measured by UV-visible spectroscopy, quartz crystal microbalance (QCM), and atomic force microscopy (AFM), respectively.

• Polymer(Korea)
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• v.24 no.3
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• pp.287-298
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• 2000

In preparing micron-sized monodisperse polystyrene beads by dispersion polymerization, the conversion, and the particle size and its distribution were affected by the reaction temperature, concentration of the monomer, solvent and initiator, molecular weight and concentration of the steric stabilizer, amount of oxygen existing in the reactor, and an appropriate combination of these starting materials. Ethanol as a dispersing agent, styrene as a monomer, PVP as a steric stabilizer, AIBN as an initiator, DVB as a cross-linking agent and toluene as a co-solvent were the basic materials for the synthesis. The reaction rate and the conversion were increased with the reaction temperature and the amount of DVB from 1 to 4%, and the conversion was saturated after 10 hours of the reaction time. The optimum reaction recipe for the preparation of the monodisperse PS beads was 25% styrene monomer, 0.5% DVB, 25% toluene, 10-15% PVP, and 2 and 4% AIBN, thereby, 3.9~4 ${\mu}{\textrm}{m}$ and 3.4~9.3 ${\mu}{\textrm}{m}$ of polystyrene beads, respectively, were successfully synthesized.

• Membrane Journal
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• v.3 no.3
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• pp.117-125
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• 1993

The CA reverse osmosis membranes were prepared and were studied the effects of parameters in membrane performance. The dope solutions were composed of polymer, formamide, acetone and 2-methoxyethanol. And it was prepared flat type membranes. The membranes were measured flux and rejection. The experimental factors such as polymer concentration, additive type, solvent evporation period, annealing temperture, and applied pressure were changed to investigate the effects of these on the membranes. And the transport parameters were also calculated at reverse osmosis medel for prepared membranes.

• Elastomers and Composites
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• v.37 no.4
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• pp.211-216
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• 2002

The polymer-polymer interaction parameter, x 23t, of the styrene-butadiene polymer (SBR) and ethylene-propylene-diene terpolymer (EPDM) was investigated by observing the phase behavior of the ternary system of SBR/EPDM/solvent. The solvent used in this study was benzene acting as a good solvent for SBR but as a poor solvent for EPDM. Ternary solutions with various concentrations and mixing ratios of the two component polymers were separated into two phases by temperature change The cloud point curves (CPC) showed that the differerence of solvent affinities toward each polymer and the repulsive interaction between two polymers considerably affect the shape of CPC near 15℃. In the temperature range of 5℃ ~ 25℃, incompatible behaviours arised from both the difference of mixing ratios and concentration were clearly observed. Also the phase separation temperature greatly influenced on the composition of each separated phase. The calculated x 23t values from Flory-Huggins theory were in the range of 0.6301 ~ 1.0775, which suggest that the SBR/EPDM systems are incompatible.

• Proceedings of the Korean Fiber Society Conference
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• 1988.06a
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• pp.24-24
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• 1988

• Polymer(Korea)
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• v.37 no.5
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• pp.553-556
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• 2013

Chlorine dioxide gas has an excellent ability for sterilization and deodorization, and is harmless to humans. However, it is very unstable and explosive as it is highly concentrated, thus its use in the air clean fields has been limited. Therefore, there is need to control chlorine dioxide gas at a low concentration for a long time. Chlorine dioxide gas could be produced slowly and sustainedly since the release of acetic acid from the polymer hydrogels delayed the reaction between acetic acid and sodium chlorite. In addition, as the amount of both acetic acid sodium chlorite loaded within the hydrogel and on the membrane increased, respectively, the generation amount of chlorine dioxide gas increased. The result shows that the use of polymer hydrogels has the potential to control the generation of chlorine dioxide gas.