• Textile Coloration and Finishing
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• v.18 no.2 s.87
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• pp.1-7
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• 2006

In order to prepare PAN nano fiber web, PAN/DMF solution was prepared and electrospun. The diameter of fiber was depended on the polymer concentration (7.5-15wt%) and the applied voltage (10-16kV). The average diameter of fiber increased with an increase of the polymer concentration and decreased with the applied voltage. At 7.5wt% concentration, many beads were found. So, we prepared a nano PAN fiber by electrospinning at concentration of 10wt% and 16kV. PAN fibers were reduced with litium aluminium hydride and the dyeability to acid dye was checked. The reduced nano PAN fiber showed much better dyeability compared with the reduced ordinary PAN fiber. It was considered that the increase of specific surface area have an important role in dyeing with acid dye.

• Membrane Journal
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• v.17 no.1
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• pp.37-43
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• 2007

The effect of anionic and cationic exchange polymer layer on the chronopotentiometry (CP) and current voltage curves (I-V) of charged composite membrane are investigated. Also, the ion transport near the interface between electrolyte and ionic exchange polymer membranes (anionic and cationic ones) and charged mosaic polymer composite membrane is studied. The results show that both anionic and cationic polymer exchange membranes exhibit lower voltage drop over range of applied current density and possess favorable industrial application potentials, especially at low KCl concentration. While the charged mosaic polymer composite membrane didn't show any current-voltage change, irrespective to the type and the concentration of used electrolyte. CP and I-V measurements are effectively used to give some fundamental understanding for ion transport behavior of ion exchange polymer membrane near the interlace.

• Polymer(Korea)
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• v.33 no.5
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• pp.429-434
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• 2009

In this study, electro spinning conditions for PMMA were studied. Namely, the ratio of DMF and THF and its maximum concentration were examined. Conductivity of the polymer solution containing silver nanoparticles and its effect on fiber diameter were also studied. As the results, the maximum concentration for the electro spinning of PMMA was found at 18 wt%, and the ratio of DMF/THF was 7:3. The diameter of nanofibers obtained was 100-400 nm when the PMMA solution containing 1000 ppm silver was electrospun. It was found, from TEM results, that silver nanoparticles were distributed on the edge of fibers and the resulting nanofiber mats showed a good antibacterial activity.

• Polymer(Korea)
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• v.29 no.1
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• pp.41-47
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• 2005

The transesterification of dimethyl terephthalate (DMT) with 1,3-propanediol (PDO) was investigated in the presence of catalyst, titanium (IV) butoxide (TBO), at 175~190 $^{\circ}C$ . The degree of transesterification reaction was measured by the output of methanol which was distilled from the reactor. The amount of methanol increased as the reaction temperature, molar ratio and catalyst concentration increased. The observed overall rate of the transesterification was third order; first order with respect to DMT, PDO, and the concentration of catalyst, respectively. Using calculated rate constants, the activation energy for transesterification was 26.93 kcal/mole. The melting temperature of bis(2-hydroxytrimethyl) terephthalate (BHTMT) was 85.2$^{\circ}C$ and heat of fusion 141.3 J/g.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.74-77
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• 2001

In order to investigate the effect of salinity level on tracking characteristics of polymer insulators for distribution power systems, tracking tests were performed by tracking wheel tester under different salt concentration. In this study, 6 kinds of polymer insulators were tested under 2200 ${\mu}\textrm{s}$/cm and 4000${\mu}\textrm{s}$/cm salinity. The salinity level has a significant effect on the tracking characteristics. Namely, most polymer insulators showed the good tracking resistance in case of low salinity level. But, in case of high salinity level some polymer insulators showed the excessive erosion and tracking. These phenomena may come from the different aging mechanism. It can be concluded that too high salinity level is not desirable in aging test of polymer insulators.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1409-1411
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• 2006

A new rod-like liquid crystalline monomer having divinyl terminal groups was synthesized and polymerized by using thiol-ene UV polymerization technique. High quality thin film with good retardation value was prepared on a rubbed alignment layer without the inert gas purging. The retardation value of the resulting film was controlled by experimental conditions such as spin speed, concentration, and spin time. From the retardation value and thickness measurement, ${\bigtriangleup}n$ was calculated to be 0.169 for the resulting film having thickness of 815.1 nm.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.71-76
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• 2000

This experimental study was conducted to figure out the drag reduction and convective heat transfer in vertical downward two-phase flow with polymer additives. The drag reduction effect were analyzed by using the difference of the pressure drop between the flow with polymer additives and without it. Experimental results show that the pressure drop with polymer additives is less than the pressure drop without polymer in vertical downward two-phase flow. And the convective heat transfer has decreased with increasing the polymer concentration in vertical downward two-phase flow.

• Bulletin of the Korean Chemical Society
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• v.8 no.1
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• pp.19-26
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• 1987

A statistical thermodynamical treatment for polymer adsorption from solution is presented. The canonical partition function for the polymer solution in the presence of a surface or an impermeable interface is formulated on the basis of usual quasi-crystalline lattice model, Bragg-Williams approximation of random mixing, and Pak's simple treatment of liquid. The present theory gives the surface excess ${\Gamma}_{exc}$ and the surface coverage ${\phi}^s_2$ of the polymer as a function of the chain length x, the Flory-Huggins parameter x, the adsorption energy parameter $x_s$, and polymer concentration $v_2$. Present theory is also applicable to the calculation of interfacial tension of polymer solution against water. For the idealized flexible polymer, interfacial tensions according to our theory fit good to the experimental data to the agreeable degrees.

• Journal of Advanced Marine Engineering and Technology
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• v.6 no.2
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• pp.21-41
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• 1982

Viscosity, especially characteristic among various properties of visco-elastic fluids such as high polymer solutions, is affected mainly by temperature and concentration. Hence, it is important for fluid engineering to express, by some equations, how the fluid characteristics vary with the change of temperature and concentration and to analyze them to obtain consistent viscous characteristics. High polymer solutions, synthetic products of modern chemical industry, suggest many interesting investigations because they are typical visco-elastic materials. Experimentation was made to derive some useful fluid characteristic equations of SEPARAN-NP10 (polyacylamide) expressed by n (flow behavior index) and K' (consistency index) when it is given temperature and concentration variation. To measure viscosity, capillary viscometer was adopted and the range of experimentation is 0-2,000 P.P.M. in concentration and 15-55 .deg.C in temperature. The experimental results are summarized as follows: The flow behavior index n 1) has nearly constant results irrespective of temperature variation at same conentration and the results are shown in (Table. 4-4-3) 2) has following equation, regardless of temperature, for the variation of concentration. n=-1.0765*10$^{-4}$ P+0.9915 (P:P.P.M.) The consistency index K' 1) has different results for the variation of temperature at same concentration and the results are given in (Table.4-7-2) 2) has following equation for the variation of concentration at same temperature. log 10$^{4}$K' =6.4785*10$^{-4}$ P-1.0529 (P:P.P.M)

• Polymer(Korea)
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• v.28 no.2
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• pp.154-161
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• 2004

Modified poly(4-vinylpyridine) was obtained by partial quarternization of nitrogen atoms in pyridine rings of poly(4-vinylpyridine) with methyl group. By means of laser light scattering and fluorescence, it was found that this modified polymer chains were aggregated in the aqueous solution and its structure was core-shell type. The hydrophobic parts of the chains were densely condensed in core part and the hydrophilic part of quarternized amino with positive charge formed the shell part. In the mixed system of modified poly(4-vinylpyridine) and anionic surfactant, sodium dodecyl sulfate, it was observed that a critical aggregation concentration existed and that this critical concentration was suddenly decreased above 0.1 M NaCl. The size change of aggregates was also investigated by dynamic light scattering while sodium dodecyl sulfate was added into polymer solution upto the critical aggregation concentration.