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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 29, Issue 6 - Dec 2005
Volume 29, Issue 5 - Sep 2005
Volume 29, Issue 4 - Jul 2005
Volume 29, Issue 3 - May 2005
Volume 29, Issue 2 - Mar 2005
Volume 29, Issue 1 - Jan 2005
Selecting the target year
Energy Transfer and Device Performance in Polymer Based Electrophosphorescent Light Emitting Diodes and Effect of Ligand Modification in the Optical and Electrical Properties of Phosphorescent Dyes
Lee Chang-Lyoul ; Das R. R. ; Noh Young-Yong ; Kim Jang-Joo ;
Polymer Korea, volume 29, issue 2, 2005, Pages 107~121
Electrophosphorescent light emitting diodes (LEDs) using phosphorescent dyes as triplet emitter, which incorporate a heavy metal atom to mix singlet and triplet states by the strong spin-orbit coupling, can achieve the theoretically
internal quantum efficiency. In this paper, we report on the performance and the energy transfer mechanism of polymer based highly efficient electrophosphorescent LEDs. The effect of phase separation and aggregation to the energy transfer between polymer hosts and phosphorescent guests and performance of polymer electrophosphorescent LEDs were investigated. Finally, the effect of introducing substitute group and ligand modification of phosphorescent dyes on optical and electrical properties are reported.
Effect of MCM-41 Preparation Methods on the Kinetics of Catalytic Pyrolysis of Linear Low Density Polyethylene
Park Young-Kwon ; Kim Joo-Sik ; Jeon Jong-Ki ; Lim Jung Eun ; Kim Ji Man ; Yoo Kyung-Seun ;
Polymer Korea, volume 29, issue 2, 2005, Pages 122~126
The effect of Al-MCM-41 preparation methods on the catalytic degradation of linear low density polyethylene (LLDPE) was investigated. Al-MCM-41 catalysts were synthesized by direct method (Al-MCM-41-D) and post treatment method (Al-MCM-41-P) and their characteristics were elucidated by XRD, BET,
MAS NMR. TGA kinetic analysis showed that the catalytic activation energies of Al-MCM-41-D and Al-MCM-41-P were 191.54 and 114.26 kJ/mol, respectively. The higher catalytic activity of Al-MCM-41-P would be attributed to its smaller pore size as well as higher number of acid sites that are accessible.
Enhancement of Compatibility and Toughening of Commingled Packaging Film Wastes
Jeon Byeong-Hwan ; Yoon Hogyu ; Hwang Seung-Sang ; Kim Jungahn ; Hong Soon-Man ;
Polymer Korea, volume 29, issue 2, 2005, Pages 127~134
The relationships among mechanical properties, rheological properties, and morphology by reactive extrusion based on commingled pckaging film wastes contains polypropylene (PP) pckaging film system [PP/polyethylene (PE)/aluminum (Al)/poly(ethylene terephthalate) (PET)] and Nylon packaging film system[Nylon/PE/linear-low density polyethylene (LLDPE)] were investigated to improve the compatibility and toughness of these wastes using various compatibilizers such as ethylene vinylacetate (EVA), styrene-ethylene/butylene-styrene triblock copolymer (SEBS), styrene-ethylene/butylene-styrene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride (PP-g-MA) , polyethylene-graft-acrylic acid (PE-g-AA) and polypropylene-graft-acrylic acid (PP-g-AA). Compared with simple melt blend system, the blends showed improvement of about
increase in physical properties when SEBS and EVA were added. However, SEBS-g-MA thermoplastic elastomer which is highly reactive with amine terminal group of nylon, resulted in about
increase in impact strength. This compatibilization effect resulted from the increase of interfacial adhesion and the reduction of domain size of dispersed phase in PP/Nylon blend system.
Preparation of PEG-Folate-graft-Polyethylenimine as a Gene Carrier
Seo Dong Hoan ; Kim Seon Hwa ; Khang GilSon ; Chi Sang Cheol ; Shin Byung Cheol ; Kim Moon Suk ;
Polymer Korea, volume 29, issue 2, 2005, Pages 135~139
In this study, poly(ethylene imine) (PEI) modified by methoxypoly(ethylene glycol) (mPEG) and folate as a gene carrier was synthesized to decrease cytotoxicity and to improve in vivo targeting. mPEG was modified by glutaric anhydride (GA) to endow carboxylic end group, followed by the activation reaction with EDC (N-ethyl-N'-(3-dimethyl-aminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide). The activated carboxylic end group of mPEG was reacted with the amines of PEI to give mPEG graft PEI. The mPEG-folate-graft-PEI was synthesized by the reaction of mPEG-PEI with folate pre-activated by EDC/NHS. The obtained copolymers were characterized by
and FT-IR. Gel retardation assay and fluorescence measurement indicated that DNA formed the complexes with the synthesized copolymers above N/P charge ratio 2. The size of complexes was ranging from 100 nm to 300 m. In conclusion, we confirmed that the synthesized copolymer have the possibility as a DNA carrier.
Effects of Polyol Types and Hard Segment Contents on the Crystallization of Thermoplastic Polyurethanes
Kim Sung Geun ; Li Ming Ji ; Ramesan M. T. ; Lee Dae Soo ;
Polymer Korea, volume 29, issue 2, 2005, Pages 140~145
Effects of the polyol type and the hard segment content of thermoplastic polyurethane (TPU) on the crystallization of hard segments in TPUs were studied employing differential scanning calorimetry. Diols used for the preparation of TPUs were poly(tetramethylene ether glycol) (PTMEG), poly(propylene glycol) (PPG), polycaprolactone (PCL), poly(butylene adipate) (PBA) the molecular weights of which were 2000 and the hard segments contents of TPUs were
. We found that crystallization of hard segments in TPUs were observed at higher temperatures and became faster with increasing hard segment contents of TPUs. The crystallization rate of TPU was also affected by the types of polyols used for the preparation of TPUs. It is postulated that lower miscibility of soft segments and hard segments results in higher crystallization rate and increase of cooling crystallization temperatures due to better hydrogen bending between hard segments in melts.
Fabrication of Microstructures Using Double Contour Scanning (DCS) Method by Two-Photon Polymerization
Park Sang Hu ; Lim Tae Woo ; Lee Sang Ho ; Yang Dong-Yol ; Kong Hong Jin ; Lee Kwang-Sup ;
Polymer Korea, volume 29, issue 2, 2005, Pages 146~150
A nano-stereolithouaphy (NSL) apparatus has been developed for fabrication of microstructures with the resolution of 150 nanometers. In the NSL process, a complicated 3D structure can be fabricated by building layer by layer, so it does not require any sacrificial layer or any supporting structure. A laminated layer was fabricated by means of solidifying liquid-state monomers using two-photon absorption (TPA) which was induced by a femtosecond laser. When the fabrication of a 3D laminated structure was finished, unsolidified liquid-stage resins were removed to develop the fabricated structure by dropping several droplets of solvent, then the polymerized structure was only left on the glass substrate. A microstructure is fabricated by vector scanning method to save the fabrication time. The shell thickness of a structure is very thin within 200 nm, when it is fabricated by a single contour scanning (SCS) path. So, a fabricated structure can be deformed easily in the developing process. In this work, a double contour scanning (DCS) method was proposed to reinforce the strength of a shell typed structure, and a microcup was fabricated to show the usefulness of the developed NSL system and the DCS method.
Effect of Acid-Base Characteristics of Carbon Black Surfaces on Mechanical Behaviors of EPDM Matrix Composites
Park Soo-Jin ; Kang Jin-Young ; Hong Sung-Kwon ;
Polymer Korea, volume 29, issue 2, 2005, Pages 151~155
The effect of acid-base treatments of carbon blacks (CBs) was investigated in the mechanical properties of CBs/rubber composites. The surface characteristics of the CBs were determined by the pH, acid-base values, and surface energetics. Their mechanical properties of the composites were also evaluated by the crosslink density
and tearing energy (T). As an experimental result, acidically treated CBs led to the increase of the specific component
, resulting in decreasing the mechanical properties of the composites. However, basically treated CBs showed a higher value of the dispersive component
than that of the untreated or acidically treated CBs. It was also found that the interaction of the CBs-rubber was improved, resulting in the improvement of the crosslink density and mechanical properties of the composites. It was then remarked that the acid-base characteristics of the CB surfaces made an important role in improving the physical properties of the rubber matrix composites.
Preparation and Properties of Poly(organosiloxane) Rubber Nanocomposite Containing Ultrafine Nickel Ferrite Powder
Kang Doo Whan ; Lee Kweon Soo ;
Polymer Korea, volume 29, issue 2, 2005, Pages 156~160
poly (dimethyl-methylphenyl) siloxane prepolymer (VPMPS ) was prepared by the equilibrium polymerization of octamethylcyclotetrasiloxane
, and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane (MVS). And also, of
poly(dimethyl-methyl)siloxane prepolymer (HPDMS) as end blocker was prepared from octamethylcyclotetrasiloxane
, and 1,1,3,3-tetramethyldisiloxane (MS). Nickel ferrite nanoparticles having spinel magnetic material was prepared by the sol-gel method using PAA as a chelating agent. Poly(organosiloxane) rubber nanocomposite containing silica and nickel ferrite ultrafine powder modified with 1,3-divinyltetramethyldisilazane (VMS) was prepared by compounding VPMPS, HPDMS, and catalyst in high speed dissolver. The mechanical properties, heat dissipating away characteristics, and volume resistivities for POX-30 and POX-50 were measured.
Preparation and Thermal Conductivity of Poly(organosiloxane) Rubber Composite with Low Hardness
Kang Doo Whan ; Yeo Hak Gue ;
Polymer Korea, volume 29, issue 2, 2005, Pages 161~165
poly(dimethyl-methylphenyl) siloxane propelymer (VPMPS ) was prepared by the equilibrium polymerization of octamethylcyclotetrasiloxane
, and 1,1,3,3-tetramethyl-1,3-divinylsiloxane (MVS) as end-blocker. And also,
poly(dimethyl-methyltrifluoropropyl)siloxane prepolymer (HPDMFS) was prepared from
, and 1,1,3,3-tetramethyldisiloxane. Poly(organosiloxane) rubber composite containing high thermal conductive filler was prepared by compounding VPMPS, HPDMFS, spherical alumina, and catalyst in high speed dissolver. The crosslinking density of poly (organosiloxane) composite was measured by oscillation rheometer. Poly(organosiloxane) composites of TC-POXR-2 and TC-POXR-4 prepared by controlling average diameters of thermal conductive filler, spherical alumina according to Horsfield's packing model were shown to 1.13 W/mK for TC-POXR-2 and 1.19 W/mK for TC-POXR-4.
Influence of Thermal Aging on the Properties of EPDM/Silicone Rubber Blends
Chung Yu-Kyoung ; Lee Sung-Goo ; Cho Bong Rae ; Choi Kil-Yeong ;
Polymer Korea, volume 29, issue 2, 2005, Pages 166~171
EPDM (ethylene propylene diene monomer)/silicone rubber blends were prepared and the influence of a compatibilizer and thermal aging on the properties of the blends was investigated. The blends of which the compositions were varied in the range of 90/10 through
were melt mixed by using a Brabender Plasticoder (internal mixer) and were vulcanized by a hot press. The morphology of the vulcanized EPDM/SR blends was examined by scanning electron microscopy (SEM). After the thermal Aging for 24, 48, 96 hrs at
in an air oven, hardness, tensile strength, elongation and contact angle of the blends were investigated. From the result of the morphology, it was confirmed that the domain size of the blends containing the compatibilizer was reduced. As the increase of the thermal aging time, hardness and tensile strength of the blends decreased but elongation and contact angle increased.
Synthesis and Properties of Water Dispersion Polyurethane Containing Fluorine
Lee Jung Eun ; Kim Hyung Joong ;
Polymer Korea, volume 29, issue 2, 2005, Pages 172~176
Environmentally friendly water dispersion polyurethanes containing fluorine were prepared with a fluorinated polyol having
. In order to control the fluorine contents of the synthesized polyurethanes polytetramethylene glycol (PTMG2000) and
were mixed at assigned ratios and reacted with isophorone diisocyanate (IPDI) as a diisocyanate used. Introducing hydrophilic anion to the polymer chain was achieved by applying dimethyl propionic acid (DMPA). The ionic groups were neutralized with triethyl amine (TEA) before dispersion into water. Chain extension was executed by adding ethylene diamine at the final stage. Mechanical properties of the polymers showed that modulus increased with increasing
content. Surface energy values obtained from contact angle measurement decreased with increasing
content up to
. We expect that the synthesized polyurethanes present reliable effect from the fluorine atoms incorporated even at a small amount of
Synthesis and Properties of Polyurethane/Clay Nanocomposites Containing Siloxane Segment
Lee Jung Eun ; Kim Hyung Joong ;
Polymer Korea, volume 29, issue 2, 2005, Pages 177~182
Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol,
. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in
solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of
Thermomechanical Characteristics of Poly(vinyl alcohol)/Chitosan Films and Its Blend Hydrogels
Park Jun Seo ; Park Jang Woo ; Kim Byung Ho ;
Polymer Korea, volume 29, issue 2, 2005, Pages 183~189
Films of poly(vinyl alcohol)(PVA)/chitosan blends and its blend hydrogels were prepared by the solution casting method. The state of miscibility of the blends and blend hydrogels were examined over the entire composition range by differential scanning carorimetry (DSC), thermogravimetry (TGA), and dynamic mechanical analysis (DMA). DSC analysis shows the depression of melting point of PVA in the blends and the decrease of crystallization temperature of PVA in the blends were observed with increasing chitosan content in the blends. TGA analysis indicates that chitosan was thermally more stable than PVA and the thermal stability of PVA in the blends was higher than that of pure PVA, due to some interactions between two component polymers in the blend. The glass transition temperature
of the chitosan and of PVA, measured by DMA, were at 160 and
, respectively. The
of the blends was changed with the content of chitosan in the blends. The results of thermal and viscoelastic analysis indicate some miscibility between component polymers in the blend exists. Moisture and cross linking in the blend and blend hydrogel, which strongly change thermal and physical properties of hydrophilic polymers, affected the miscibility of chitosan and PVA to a small extent.
Polyester Nanocomposite Fibers with Organoclay; Thermo-Mechanical Properties and Morphology of PBT, PET, and PTT
Kim Sung Jong ; Mun Mu Kyung ; Chang Jin-Hae ;
Polymer Korea, volume 29, issue 2, 2005, Pages 190~197
Nanocomposites of three different polyesters with dodecyltriphenylphosphonium-montmorillonite
as an organoclay are compared with their thermal properties, mechanical properties, and morphologies. Poly (butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and poly(trimethylene terephthalate) (PTT) were used as matrix polymers in the fabrication of polyester nanocomposite fibers. The variations of their properties with organoclay content in the polymer matrix and draw ratio (DR) are discussed. Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nano-scale, although some clay particles are agglomerated. We also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the polyester nanocomposite fibers. Even polymers with low organoclay contents $(<5\;wt\%)$ were found to exhibit much higher strength and modulus values than pure polyester fibers. In the cases of all polyester hybrid fibers, the values of the tensile mechanical properties were found to decrease linearly with increasing DR. However, the initial tensile modulus of the PTT hybrid fibers were found to be independent of DR.
Preparation of Poly(L-lactic acid) Scaffolds by Melt Extrusion Foaming
Lee Jong Rok ; Kang Ho-Jong ;
Polymer Korea, volume 29, issue 2, 2005, Pages 198~203
Melt extrusion foaming process for the preparation of poly(L-lactic acid) (PLLA) scaffolds was carried out and the effects of foaming conditions on the pore structure of PLLA scaffolds and their mechanical properties were investigated. The porosity and mechanical properties of fabricated scaffolds were compared with the scaffolds obtained from the salt leaching method as well. It was found that the optimum pore structure was achieved when the PLLA melt was kept in extruder for the maximum decomposition time of blowing agent. In order to maintain the proper scaffolds structure, the blowing agent content should be less than
. It can be concluded that melt extrusion foaming process allows for the production of scaffold having higher mechanical properties with reasonable pore size and open cell structure for hard tissue regeneration even though it has less porosity than scaffolds made by salt leaching process.
Synthesis and Property of Colorless Polyimide and Its Nanocomposite for Plastic Display Substrate
Ma Seung Lac ; Kim Yong Seok ; Lee Jae Heung ; Kim Jung Su ; Kim Insun ; Won Jong Chan ;
Polymer Korea, volume 29, issue 2, 2005, Pages 204~210
We describe a colorless, transparent polyimide films for plastic display substrate which should have heat resistance, roll-to-roll processability and low CTE (coefficient of thermal expansion) property. Colorless polyimides were synthesized from 3,3',4,4'-oxydiphthalic anhydride (ODPA) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and diamines such as sulfonyldianiline, aminophenoxybenzene (TPE-p, TPE-q, TPE-r) and bis[4-(3-aminophen oxy)phenyl] sulfone (m-BAPS). Their optical properties were measured by UV spectrophotometer, colormeter and hazemeter. We prepared polyimide/organophilic layered silicate nanocomposite to improve dimension stability. These colorless polyimide films showed UV transmittance by the level upper
, at 440 nm and excellent optical property having the value under yellow index (YI)=7. In addition, polyimide nanocomposite films also showed an improvement of CTE value as decreased according to the amount of layered silicate contents.
Effect of Phosphorous-Based Flame Retardants on the Weight, Diameter, and Thermal Stability after Stabilization Processes of Rayon Fibers for Carbon Fibers
Yoon Sung Bong ; Cho Donghwan ; Park Jong Kyoo ;
Polymer Korea, volume 29, issue 2, 2005, Pages 211~215
Stabilization process is absolutely necessary to convert the precursor fibers into chemically, physically, thermally and structurally stable carbon fibers. Especially, it is critically important for rayon fibers experiencing severe weight loss and thermal shrinkage occurring at the stabilization stage below
. The stabilization of rayon fibers strongly depends not only on stabilization temperature but also on heating rate, chemical pre-treatment, atmosphere, and so on. In the present study, the weight loss, fiber diameter change occurred in the furnace during the stabilization process for rayon fibers produced with various heating rates and in the absence and presence of phosphorous-based flame retardants and the thermal stability of the stabilized fibers were investigated. The result indicates that the weight, diameter and thermal stability of the rayon fibers are significantly affected by the type and amount of the flame retardant used. It is also suggested that the pre-treatment of rayon fibers with a concentration lower than
of phosphoric acid is most desirable for further carbonization process of stabilized rayon fibers.
A Study on the Preparation and Characterization of Gel Polymer Electrolyte from Poly(ethylene glycol) Diacrylate in Sonic Liquid
Shin Bora ; Cho Mi Suk ; Kim Dukjoon ; Sim Sang Jun ; Kim Ji-Heung ; Lee Dong Hyun ; Nam Jae-Do ; Lee Youngkwan ;
Polymer Korea, volume 29, issue 2, 2005, Pages 216~220
A new type of polymer gel electrolyte was prepared from poly(ethylene glycol) diacrylate(PEGDA) and 1-butyl-3-methylimidazolium bis((trifluorornethyl) sulfonyl) amide
ionic liquid. The effect of the ionic liquid on ionic conductivity of the gel polymer electrolyte was investigated. It was observed that the gel polymer electrolyte having the ionic liquid exhibited higher ionic conductivity
as well as electrochemical stability than that using organic solvent.