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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Polymer Society of Korea
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Volume & Issues
Volume 33, Issue 6 - Nov 2009
Volume 33, Issue 5 - Sep 2009
Volume 33, Issue 4 - Jul 2009
Volume 33, Issue 3 - May 2009
Volume 33, Issue 2 - Mar 2009
Volume 33, Issue 1 - Jan 2009
Selecting the target year
Effect of Dispersant Contents on the Dispersity of Conductive Carbon-black and Properties of Screen-printed Source-drain Electrodes for OTFTs
Lee, Mi-Young ; Bae, Kyung-Eun ; Kim, Seong-Hyun ; Lim, Sang-Chul ; Nam, Su-Yong ;
Polymer Korea, volume 33, issue 5, 2009, Pages 397~406
We have fabricated source-drain electrodes for OTFTs using a screen-printing technique with carbon-black pastes as conductive paste. And effects of dispersants contents (SOP 10-40%) on the dispersity of carbon-black pastes and characteristics of screen-printed source-drain electrodes for OTFTs using two types of dispersants (DB-2150, DB-9077) were investigated. As contents of both dispersants were increased the dispersity of carbon-black mill-bases was improved, whereas the carbon-black pastes exhibited different dispersion characteristics. For the case of DB-2150, the dispersity of the pastes was improved with increasing dispersant content and the storage modulus G' in their rheology characteristics were reduced. But, for the DB-9077, the storage modulus G' of pastes were increased with dispersant content due to the flocculated network structure formed by interactions among carbon-black powders and dispersants. But, since this flocculated network structure of the pastes using DB-9077 resulted in the conduction path of carbon-black structures, the conductivities of screen-printed electrodes and mobilities of the OTFTs with them were better than those using pastes with DB-2150.
Enhanced Efficiency of Organic Electroluminescence Diode Using PEDOT-PSS/NPD-
Hole Injection/Transport Layers
Park, Kyeong-Nam ; Kang, Hak-Su ; Senthilkumar, Natarajan ; Park, Dae-Won ; Choe, Young-Son ;
Polymer Korea, volume 33, issue 5, 2009, Pages 407~412
Vacuum deposited N,N-di-1-naphthyl-N,N-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD) as a hole transporting (HTL) materials in OLEDs was placed on PEDOT-PSS, a hole injection layer (HIL). PEDOT-PSS was spin-coated on to the ITO glass.
(10 wt%) film was formed via co-evaporation process and the morphology of NPD-
films was investigated using XRD and AFM. The J - V, L - V and current efficiency of multi -layered devices were characterized. According to XRD results, the deposited
thin film was partially crystalline, but NPD-
film was observed not to be crystalline, which indicates that
molecules are uniformly dispersed in the NPD film. By using
film as a HTL, the current density and luminance of multi-layered ITO/PEDOT-PSS/NPD-
/LiF/Al device were significantly increased by about 80% and its efficiency was improved by about 25% in this study.
Improvement of Brightness in UV Curing Type Prism Sheet by Using Aromatic Groups
Kim, Dong-Ryoul ; Kim, Hyung-Il ;
Polymer Korea, volume 33, issue 5, 2009, Pages 413~419
As the refractive index of the prism layer becomes higher, the optical performance of the prism sheet gets better and the efficiency of the LCD backlight unit is improved. In order to increase the refractive index of the prism layer, the ultraviolet curing type resins were prepared by mixing high refractive index materials containing aromatic groups and the multi-functional reactive diluents. By using 9,9-bis [4-(2-acryloyloxyethoxy)phenyl] fluorene, the refractive index of the prism layer was increased up to 1.58 and the brightness of the backlight unit was improved. Since the light source used in the backlight unit caused the yellowing in the prism sheet and deteriorated the brightness accordingly, the hindered amine light stabilizer was used to improve the yellowing resistance successfully.
Microwave Absorbing Characteristics of Epoxy Composites Containing Carbon Black and Carbon Fibers
Lv, Xiao ; Yang, Shenglin ; Jin, Junhong ; Zhang, Liang ; Li, Guang ; Jiang, Jianming ;
Polymer Korea, volume 33, issue 5, 2009, Pages 420~428
In this study, the composites containing carbon black (CB) or carbon fibers were prepared, and the microwave absorbing properties and the absorption mechanism of them were investigated and discussed in the frequency range of 2-18 GHz, respectively. The optimum mass fraction of CB has been found as 6%, and the carbon fibers were discovered to absorb radar wave either under parallel or vertical polarization, the suitable gap distance between each bundle of which was 5 mm. According to the results of the single constitute absorber samples, the structured composites with the two kinds of absorbers combination were fabricated and studied at 2-18 GHz. The top layer absorbers affect the absorption performance a lot; the maximum reflection loss of composites with CB as top layer absorbers was -31.8 dB with the frequency range of 2.4 GHz below -10 dB, and the other type with CFs as the top layer absorbers obtained the reflection loss peak value of -31.4 dB with 2 GHz below-10 dB.
Preparation of Antibacterial Nanofibrous PMMA Nonwoven Fabrics
Kim, Chang-Nam ; Xing, Zhi-Cai ; Baek, Jin-Young ; Bae, Hyun-Su ; Kang, Inn-Kyu ;
Polymer Korea, volume 33, issue 5, 2009, Pages 429~434
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.
Non-isothermal TGA Analysis on Thermal Degradation Kinetics of Modified-NR Rubber Composites
Oh, Jeong-Seok ; Lee, Joon-Mann ; Ahn, Won-Sool ;
Polymer Korea, volume 33, issue 5, 2009, Pages 435~440
Thermal degradation behavior of CR (chloroprene) -modified NR (natural rubber) compounds, having different sulfur/accelerator compositions, was studied by non-isothermal TGA method. Data were analyzed using both Kissinger and Flynn-Wall-Ozawa analysis to assess the activation energies. Activation energy obtained from Kissinger analysis was
kJ/mol for all samples, showing little effect of sulfur/accelerator composition changes in the samples. On the other hand, activation energy from Flynn-Wall-Ozawa analysis exhibited much variations with conversion, showing average value of
kJ/mol. From the results, it was considered that whole thermal degradation processes of the samples were composed of complex multiple step processes, of which reaction mechanisms were different from each other.
Effect of P(MAA-co-PEGMA) Hydrogel Compositions and Loading pH on the Loading Efficiency of Cosmetic Active Agents
Lee, Eun-Mi ; Kim, Kyu-Sik ; Kim, Bum-Sang ;
Polymer Korea, volume 33, issue 5, 2009, Pages 441~445
In order to develop an intelligent delivery system for cosmetic active agents (e.g., arbutin, ascorbic acid, and adenosine), pH-responsive P(MAA-co-PEGMA) hydrogel particles having an average size of approx.
and spherical shape were synthesized via dispersion photopolymerization. There was a drastic change in the swelling ratio of P (MAA-co-PEGMA) hydro gels at a pH 5, which is the
of the hydrogel. To determine the factors that have an effect on the loading of cosmetic active agents into the hydrogel, the loading efficiency of the active agents was investigated at various MAA and EG compositions of the hydrogel and the loading pH conditions. When the MAA contents in the hydrogel decreased, the loading efficiency of the active agents increased. In loading experiments with different pH conditions, the active agents showed higher loading efficiency into the hydrogel at the pH where the hydrogel was at the swollen state than at the pH where the electrostatic repulsion was minimized.
Mechanical Property Behaviors of Polyethylene Pipe due to Thermal-Degradation
Weon, Jong-Il ; Choi, Kil-Yeong ;
Polymer Korea, volume 33, issue 5, 2009, Pages 446~451
Reliability evaluations of linear low density polyethylene (LLDPE) pipe with respect of thermal exposure time have been investigated in accordance with RS M 0042, which is a reliability standard for polymer pipe. As the thermal exposure time is prolonged, a progressive increase, until 250 days, in tensile strength and a slight increase in hardness are observed, while a proportional decrease in elongation at break is showed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density, chain scission and the decrease in chain mobility, due to thermal oxidation as the exposure time increases. Long term hydrostatic pressure test result implies the existence of transition point from ductile to brittle fracture. Oxidation induction time (OIT) test is employed to monitor the thermo-oxidative degradation of LLDPE pipe. This result shows that after the exposure time is 250 days, the depletion of antioxidants added in LLDPE pipe occurs. An empirical equation as function of exposure time, under
thermal-degradation condition, is proposed to assess the remaining amount of antioxidants owing to thermo-oxidative degradation. Fourier transform infrared spectroscopy results show the increase of carbonyl (-C=O) and hydroxyl (O-H) function groups on the surface of thermally exposed LLDPE pipe. This result suggests that the hydrocarbon groups locally undergo the oxidation on the LLDPE surface due to thermal-degradation.
Preparation of Core/Shell Nanoparticles Using Poly(3,4-ethylenedioxythiophene) and Multi-Walled Carbon Nanotube Nanocomposites via an Atom Transfer Radical Polymerization
Joo, Young-Tae ; Jin, Seon-Mi ; Kim, Yang-Soo ;
Polymer Korea, volume 33, issue 5, 2009, Pages 452~457
Hybrid nanomaterials consisting of multi-walled carbon nanotube(MWNT) and/or PEDOT of conductive polymer were prepared in this study. In the presence of catalyst and ligand, the MWNT-Br compound prepared by the successive surface treatment reaction was mixed with MMA to initiate the atom transfer radical polymerization process. PMMA was covalently linked to the surface of MWNT for the formation of MWNT/PMMA nanocomposites. The EDOT and oxidant were added in the aqueous emulsion of PS produced via a miniemulsion polymerization process and then it proceeded to carry out the oxidative chemical polymerization of EDOT for the preparation of PEDOT/PS nanoparticles with the core-shell structure. The aqueous dispersion of PEDOT:poly(styrene sulfonate) (PSS) was mixed with the silica particles treated with a silane compound and thus PEDOT:PSS-clad silica nanoparticles were prepared by the surface chemistry reaction. The hybrid nanomaterials were analyzed by using TEM, FE-SEM, TGA, EDX, UV, and FT-IR.
Synthesis of Polystyrene-b-Poly(ethylene oxide)-b-Polylactide Copolymers via Sequential Anionic and Ring-Opening Polymerizations
Song, Jie ; Cho, Byoung-Ki ;
Polymer Korea, volume 33, issue 5, 2009, Pages 458~462
We have synthesized ABC linear triblock copolymers, i.e., polystyrene-b-poly(ethylene oxide)-b-polylactide, via sequential anionic and ring-opening polymerizations. In the first anionic polymerization step, styrene was polymerized in cyclohexane using sec-butyllithium as the initiator. Poly (styryl) lithium was hydroxylated by the addition of ethylene oxide, and the subsequent protonation with methanolic HCl. In the second anionic polymerization step, potassium naphthalenide was used to deprotonate the hydroxyl group of the PS to generate the macroinitiator of PS-
. Polymerization of ethylene oxide was performed in THF and terminated with methanolic HCl. In the ring-opening polymerization step, the PS-b-PEO-
macroinitiator was prepared from an
/pyridine system in THF, and the polymerization of lactide was performed at
. The resulting block copolymers showed well-defined molecular weights and narrow molecular weight distributions as revealed by
- NMR spectroscopy and gel permeation chromatography (GPC).
Micron-Sized Hollow Plastic Pigment
Choi, Gwang-Sik ; Kim, Yang-Soo ; Jung, Hoon-Sang ; Jang, Seo-Won ; Kim, Nam-Seon ;
Polymer Korea, volume 33, issue 5, 2009, Pages 463~468
Syntheses of monodisperse and micron-sized hollow plastic pigment (HPP) were carried out through the core-shell reaction. The effects of the reaction parameters, such as the particle size, molecular weight, the swelling time, agitation rate, and the solid contect were investigated. This micron-sized HPP could be made by using the alkali soluble core with at least bigger than 200 nm size. To obtain a higher opacity ratio, the swelling time and molecular weight of the core should be controlled. The agitation rate affected the particle's morphology. To prevent the shell destruction, the agitation rate must be sufficiently low in case of the syntheses of micron-sized HPP. In this study, micron-sized HPP exhibiting the high hiding power and narrow particle distribution could be obtained.
Preparation and Characterization of Biodegradable Superporous Hydrogels
Yuk, Kun-Young ; Choi, You-Mee ; Park, Jeong-Sook ; Kim, So-Yeon ; Park, Ki-Nam ; Huh, Kang-Moo ;
Polymer Korea, volume 33, issue 5, 2009, Pages 469~476
In this study, biodegradable superporous hydrogels(SPHs) with fast swelling and superabsorbent properties were prepared using biodegradable crosslinkers and their physicochemical properties were characterized. A biodegradable crosslinker (PLA-PEG-PLA DA) was synthesized by a ring opening polymerization of D,L-lactide (LA) using hydrophilic poly(ethylene glycol) as a macroinitiator, followed by diacrylation of the end groups for the introduction of polymerizable vinyl groups. Various kinds of hydrogels with different chemical compositions were prepared and characterized in terms of swelling ratio, swelling kinetics, and biodegradation properties. The synthetic results were confirmed by
-NMR, FT-IR and GPC measurements, and the porous structures of the prepared SPHs and their porosities were identified by a scanning electron microscope and mercury porosimetry, respectively. The physicochemical properties of SPHs could be controlled by varying their chemical compositions and their cytotoxicity were found to be very low by MTT assay.
Suspension Polymerization with Hydrophobic Silica as a Stabilizer III. Poly(butyl methacrylate) Composite Particles Containing Carbon Black
Moon, Ji-Yeon ; Park, Moon-Soo ;
Polymer Korea, volume 33, issue 5, 2009, Pages 477~484
Suspension polymerization with hydrophobic silica as a stabilizer and AIBN as an initiator was conducted to synthesize PBMA particles and PBMA composite particles containing carbon black. Surface modification of silica particles by controlling pH revealed that 90% of them functioned as stabilizer and 10% were incorporated into PBMA particles. While stabilizer concentration had no impact on reaction kinetics and particle diameter, an increase in stabilizer concentration displayed an increase in molecular weights when it exceeded 1.67 wt%. An increase in initiator concentration and reaction temperature decreased molecular weights in close agreement with the theoretical equation. An increase in carbon black concentration from 1 to 7 wt%, relative to the monomer, showed a progressive decrease in reaction conversion. As carbon black was increased from 3 to 5 wt%, glass transition showed a
increase. The presence of carbon black was confirmed by TEM while its concentration was measured by TGA.
Small-Angle Neutron Scattering Study of the Structure of Micelles Formed by a Polystyrene-Poly(ethylene oxide) Diblock Copolymer in Aqueous Solution
Kang, Byoung-Yook ; Choi, Mi-Ju ; Hwang, Kyu-Hee ; Lee, Kwang-Hee ; Jin, Byoung-Suk ;
Polymer Korea, volume 33, issue 5, 2009, Pages 485~489
The temperature dependence of the structure of micelles formed by a deuterated polystyrene-poly(ethylene oxide) diblock copolymer (dPS-PEO) in heavy water were investigated with small-angle neutron scattering (SANS). SANS data were analyzed using the hard-sphere structure factor in combination with the form factor of a core-shell model. The micelle aggregation number and corona radius were obtained from the fits to the SANS data. The micelle aggregation numbers varied with temperature from 229 at
to 240 at
, with a corresponding increase in the core radius. However, the shell thickness of micelles decreased with increasing temperature from 6.2 to 5.8 nm. These structural changes of micelles might be ascribed to the decrease in the hydration volume per hydrophilic group in the corona because of the increase in hydrophobicity of the PEO block with increasing temperature.
Reactive Compatibilization of Amorphous Poly-
-olefins/Amorphous Polyamide Blends
Yun, Deok-Woo ; Choi, Mi-Ju ; Hwang, Kyu-Hee ; Kim, Geon-Seok ; Lee, Kwang-Hee ;
Polymer Korea, volume 33, issue 5, 2009, Pages 490~495
The reactive compatibilization of amorphous poly-
-olefins (APAO)/amorphous polyamide (aPA) blends was carried out using two kinds of reactive compatibilizers such as maleated polypropylene and ethylene-glycidyl methacrylate-methyl acrylate copolymer. The grafting reaction rates between aPA and the compatibilizers were examined using FT-IR, SEM and rheometer. The effect of the reactive compatibilization on the mechanical property of the blends was investigated with a universal testing machine. The adhesion strength of the blends including a hydrocarbon tackifier resin, C9 was also measured.
Study on Electro-optic Characteristics of the Optically Compensated Bend Liquid Crystal Display Using UV Curable Monomer
Lim, Young-Jin ; Jeon, Eun-Jeong ; Kwon, Dong-Won ; Kim, Jeong-Hwan ; Jeong, Kwang-Un ; Lee, Myong-Hoon ; Lee, Seung-Hee ;
Polymer Korea, volume 33, issue 5, 2009, Pages 496~500
Optically compensated bend liquid crystal display (OCB-LCD) has many application fields owing to its fast response time and wide viewing angle. However, in order to operate the OCB-LCD in bend state, this device needs quick transitions from the initial splay state to bend state. Unlike conventional approach using transient high voltage for the transition, the OCB-LCD with high surface tilt angle, which was achieved by polymerization of UV curable reactive mesogen monomer under certain voltage, was manufactured and the cell showed bend state initially. Electro-optic and electrical characteristics of the cell were analyzed. The cell shows a fast response time owing to high surface pretilt angle and very low residual DC less than 0.1 V although another polymer layer is formed above polymer alignment layers.
Analysis on Thermal Degradation of Poly(
-glutamic acid) Sodium Salt by means of Light Scattering and Viscometry
Park, Il-Hyun ; Eom, Hyo-Sang ; Kwon, Hyo-Lee ;
Polymer Korea, volume 33, issue 5, 2009, Pages 501~508
The thermal degradation experiment of sodium salt of poly (
-glutamic acid) (PGGNa) has been carried out in both its solid phase and solution phase at the range of
and their molecular weight decreasing effect was analyzed as a function of time by means of viscometry and light scattering. Based on the solid phase degradation results, it was supposed that the bond scission rate in a polymer chain kept constant and that the bond scission was occurred on a randomly located position in a polymer chain. For the degradation in solution phase, it was also found that all data at various temperatures were dropped on a single master curve when the reduced time
was used in the plot of the reciprocal intrinsic viscosity (or molecular weight). This degradation curve in solution phase could be expressed as the sum of a single exponential and a linear equation and especially, the single exponential character appeared only at the beginning stage. The activation energy was measured as
kJ/mol in this study and agreed with the literature values.
Effect of Lithium Bromide on Chitosan/Fibroin Blend
Kim, Hong-Sung ; Park, Sang-Min ; Yoon, Sang-Jun ; Hwang, Dae-Youn ; Jung, Young-Jin ;
Polymer Korea, volume 33, issue 5, 2009, Pages 509~513
For examining an effect of lithium bromide on structure and property of chitosan/fibroin blend, we investigated the structural characteristic of chitosan/fibroin blend films using solution with lithium bromide which was removed during a casting. The chitosan/fibroin blend formed a complex with the dissolved bromine/lithium ions. The crystalline phase of the complex was found in the blend film at LiBr concentration of 0.6 mol/L. The degree of crystallization was decreased with increasing the concentration of LiBr. The hydrated crystalline phase of chitosan was formed in the blend film that lithium bromide was removed in the process of casting by neutralization and osmotic action. The crystallinity of this film was increased largely as compared with that of the film without lithium bromide. The complexed blend film formed hydrogel absorbing plenty of water.