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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 35, Issue 6 - Nov 2011
Volume 35, Issue 5 - Sep 2011
Volume 35, Issue 4 - Jul 2011
Volume 35, Issue 3 - May 2011
Volume 35, Issue 2 - Mar 2011
Volume 35, Issue 1 - Jan 2011
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Measurement of Residual Stress Using Photoelasticity and Computer Simulation of Optical Characteristics in a Transparent Injection Molded Article
Hong, Jin-Soo ; Park, Seo-Ri ; Lyu, Min-Young ;
Polymer Korea, volume 35, issue 1, 2011, Pages 1~6
Pressurized high temperature plastic resin flows into the cavity of mold and is solidified in injection molding process. Residual stress is being developed in injection molded part because of high temperature variations and high pressure. Developed residual stress relaxes as time goes. Consequently this makes part deformed and deteriorates quality of product. A measurement method of residual stress for injection molded transparent articles has been investigated using photoelasticity. Light, a composite of electromagnetic waves, is purified into a single wave by a polarized film. When this wave passes through the specimen, birefringence is developed according to the level of residual stress in the specimen and color fringed pattern appears after the second polarized film. Residual stress in the injection molded transparent flat a part has been measured quantitatively using the color fringed pattern. Optical characteristics have been a part also predicted by computer simulation and compared with experimental results.
Effect of PLGA/Silk Fibroin Hybrid Film on Attachment and Proliferation of Schwann Cells
Kim, Hye-Lin ; Yoo, Han-Na ; Park, Hyun-Jin ; Kim, Yong-Gi ; Lee, Dong-Won ; Kang, Young-Sun ; Khang, Gil-Son ;
Polymer Korea, volume 35, issue 1, 2011, Pages 7~12
Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable synthetic polymer with acceptable mechanical strength and well-controlled degradation rate. Also, it can be easily fabricated into many shapes. Silk fibroin contains powerful bioactive molecules. We fabricated natural/synthetic hybrid films using 0, 10, 20, 40 and 80 wt% of silk fibroin. Schwann cells (SCs) were seeded on PLGA/silk fibroin hybrid films and confirmed the effects of adhesion and proliferation on SCs according to the content of silk fibroin. In this study, we confirmed PLGA/silk fibroin hybrid film containing 40% and 80% of silk fibroin interrupted adhesion and proliferation of SCs. Films containing 10% and 20% of silk, however, provided suitable environment for growth and proliferation of SCs. These results suggest that silk fibroin provides suitables surface to neural cells and its proper content provides proper culture conditions to improve cell adhesion and proliferation.
Preparation and Characterization of Polyvinylpyrrolidone/
-Carrageenan/Hexanediol Hydrogel by Gamma-ray Irradiation
Han, Il-Soo ; Lim, Youn-Mook ; Gwon, Hui-Jeong ; Park, Jong-Seok ; Nho, Young-Chang ;
Polymer Korea, volume 35, issue 1, 2011, Pages 13~16
In this study, the hydrogels composed of polyvinylpyrrolidone (PVP),
), and 1,2-hexanediol (HD) were prepared by
-ray irradiation. The radiation dose was 25 kGy and the concentration of
was 3 wt%. The physical properties of the hydrogels were investigated as a function of the concentrations of PVP and HD. The gel content and the tensile strength increased with increasing PVP concentration due to the crosslinking between the pyrrolidone molecules and decreased with increasing HD concentration. The degree of swelling was inversely proportional to the gel content because the highly crosslinked hydrogels had a tighter structure, hence reducing their water absorption. The antibacterial tests indicated that the hydrogels containing HD had antibacterial activity.
Properties of PP/MWCNT Nanocomposite Using Pellet-Shaped MWCNT
Jeong, Dong-Seok ; Nam, Byeong-Uk ;
Polymer Korea, volume 35, issue 1, 2011, Pages 17~22
Polypropylene/multi-walled carbon nanotube(PP/MWCNT) composites along with various MWCNT contents up to 20 wt% were prepared by a twin screw extruder. Nanocomposites having 20 wt% MWCNT as a master batch(M/B) were diluted with PP by way of melt compounding. The electrical/thermal conductivity, morphology, thermal/viscoelastic/mechanical properties were investigated with the variation of MWCNT contents. Also, we compared some properties between 1-step PP/MWCNT and the diluted PP/MWCNT composites. The percolation threshold of electrical and thermal conductivity was measured at about 3 wt% MWCNT. And conductivity of diluted PP/MWCNT composites were superior to those of PP/MWCNT composites. The non-isothermal crystallization temperature and thermal decomposition temperature appeared at higher temperatures with increasing MWCNT contents. Morphology showed that length of MWCNT in diluted PP/MWCNT composites was shortened by twice melt blending, which contributed to improve the tensile strength of PP/MWCNT composites.
Effect of Chemical Composition, Molecular Weight, Carbon Black Concentration and Temperature on the Flow Behavior of Styrene/Butyl Methacrylate Homo- and Co-polymer Particles
Park, Moon-Soo ; Moon, Ji-Yeon ;
Polymer Korea, volume 35, issue 1, 2011, Pages 23~29
We measured shear viscosity of polymeric particles, prepared by suspension polymerization with hydrophobic silica as a stabilizer at
, by a capillary rheometer. Shear viscosity displayed a non-Newtonian behavior with an increase in weight average molecular weight. Measurement of shear viscosity at 170 and
with copoly(styrene/butyl methacrylate) (co-PSB) particles by varying the ratio between styrene (St) and butyl methacrylate (BMA) showed that shear viscosity was a function of molecular weight, temperature and compositional ratio. When the ratio was 7/3, 5/5 and 3/7, shear viscosity slightly reduced with an increase in BMA concentration despite similar weight average molecular weights. We found that shear viscosity of copolymers with BMA concentrations exceeding 70% displayed a sharp reduction at high shear rates. It is speculated that increased PBMA chain length contributes to enhanced flowability of copolymers. When carbon black was incorporated into co-PSB, shear viscosity progressively increased with increasing carbon black concentration. The increase in shear viscosity, however, was less pronounced compared to the cases of molecular weight increase.
Thermal Behavior and Abrasion Properties of Glass Fiber Reinforced Nylon 12 Crosslinked by Electron Beam Irradiation
Shin, Bum-Sik ; Jeun, Joon-Pyo ; Kim, Hyun-Bin ; Kang, Phil-Hyun ;
Polymer Korea, volume 35, issue 1, 2011, Pages 30~34
In this study, the effects of the electron beam irradiation on the thermal behavior and the abrasion properties of the glass fiber reinforced nylon 12 was investigated. The electron beam irradiation was carried out over a range of irradiation dose from 100 to 600 kGy with additive crosslinking agents such as triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) and trimethylolpropane trimethacrylate (TMPTMA) for enhancing the crosslinking effects. The gel contents were increased dramatically above 200 kGy. It was verified that the degree of crosslinking depends on the radiation dose. The decreases of the melting temperature and the area of endothermic peak were observed as increasing the absorbed dose in the results of DSC analysis. The enhanced thermal stability was confirmed by the increases of decomposition temperature by electron beam irradiation. Furthermore, the negative deviations of the abrasion loss and the abrasion coefficients confirmed the improvement of the abrasion properties of irradiated nylon 12, as evidenced by SEM observation on the abrasion surfaces. The addition of the crosslinking agents to nylon 12 during effectively improved the thermal behavior and the abrasion properties of nylon 12 by the electron beam irradiation.
Influence of Activation of Mesoporous Carbon on Electrochemical Behaviors of Pt-Ru Nanoparticle Catalysts for PEMFCs
Kim, Byung-Ju ; Park, Soo-Jin ;
Polymer Korea, volume 35, issue 1, 2011, Pages 35~39
In this work, mesoporous carbons (CMK-3) were prepared by a conventional templating method using mesoporous silica (SBA-15) for using catalyst supports in polymer electrolyte membrane fuel cells (PEMFCs). The CMK-3 were chemically activated to obtain high surface area and small pore diameter with different potassium hydroxide (KOH) amounts, i.e., 0, 1, 3, and 4 g as an activating agent. And then Pt-Ru was deposited onto activated CMK-3 (K-CMK-3) by a chemical reduction method. The characteristics of Pt-Ru catalysts deposited onto K-CMK-3 were determined by surface area and pore size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and inductive coupled plasma-mass spectrometry (ICP-MS). The electrochemical properties of Pt-Ru/K-CMK-3 catalysts were also analyzed by cyclic voltammetry (CV). From the results, the K3g-CMK-3 carbon supports activated with 3 g KOH showed the highest specific surface areas. In addition, the K3g-CMK-3 led to uniform dispersion of Pt-Ru onto K-CMK-3, resulted in the enhancement of elelctro-catalystic activity of Pt-Ru catalysts.
Synthesis, Characterization and Haemocompatibility of Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers
Ren, Ping ; Wu, Yi-Bo ; Guo, Wen-Ii ; Li, Shu-Xin ; Mao, Jing ; Xiao, Fei ; Li, Kang ;
Polymer Korea, volume 35, issue 1, 2011, Pages 40~46
The synthesis of well-defined poly(styrene-b-isobutylene-b-styrene) (SIBS) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) with styrene (St) using 1,4-di(2-chloro-2-propyl) benzene (DCC) /
/2,6-di-tert-butylpyridine(DtBP) as an initiating system in methyl chloride (
)/methylcyclohexane(MeChx) (50/50 v/v) solvent mixture at
. The triblock copolymers exhibited excellent thermoplastic and elastomeric characteristics. Tensile strengths and Shore hardness increased with increasing polystyrene (PS) content, while elongation at break decreased. The blood-compatibility of SIBS was assessed by SEM observation of the platelet adhesion, blood clotting time and haemolysis ratio. The haemolysis ratios were below 5% which met the medical materials standard. The platelet adhesion test further indicated that SIBS block copolymers had a good blood compatibility.
Influence of Fluoro-illite on Flame Retardant Property of Epoxy Complex
Yu, Hye-Ryeon ; Jeong, Eui-Gyung ; Kim, Jin-Hoon ; Lee, Young-Seak ;
Polymer Korea, volume 35, issue 1, 2011, Pages 47~51
In this study, illite, an environmental friendly, low cost, and high aspect ratio additive, was used to improve flame retardant property of epoxy and it was fluorinated to enhance dispersion of hydrophilic illite in hydrophobic epoxy by introducing hydrophobic functional groups. Fluorination of illite enhanced illite dispersion ill epoxy solution before curing and that in the complex after curing. These enhanced dispersions were attributed to the increased affinity of illite to hydrophobic epoxy solution induced by fluorination of illite and the increased intercalation of epoxy polymer or exfoliation of illite by epoxy curing. Hence, limited oxygen index(LOI) of fluorinated illite/epoxy complex increased by 24%, compared to that of epoxy, suggesting that the preparation of fluorinated illite/epoxy complex increased their flame retardant properties.
Synthesis and Characterization of Poly(L-lactide)(L-PLA), Poly(D-lactide)(D-PLA) and Stereocomplex-poly(lactide)(PLA)
Kim, Ji-Hyun ; JeGal, Jong-Geon ; Song, Bong-Keun ; Shin, Chae-Ho ;
Polymer Korea, volume 35, issue 1, 2011, Pages 52~59
L-PLA or D-PLA was synthesized in bulk at
by ring opening polymerization(ROP) of L-lactide or D-lactide as a monomer using tin(II) octoate and lauryl alcohol as a catalyst and an initiator with changing the amounts of catalyst(0.25~1.0 wt%) and initiator(0.l~0.5 wt%). And stereocomplex-PLA was prepared by L-PLA/D-PLA having a wide range of molecular weight(30000~90000 g/mol) and L-PLA/D-PLA blends having different mixing ratio (
). The melting temperature. thermal degradation temperature and thermal stability of stereocomplex-PLA were higher than those of homopolymers(L-PLA, D-PLA). We supposed that these improvements arose from a strong interaction between L-PLA and D-PLA. The improved mechanical properties and changes in morphology of LPLA/D-PLA blends were compared to those of homopolymers(L-PLA, D-PLA).
Quantitative Dispersion Evaluation of Carbon Nanotubes Reinforced Polymer Nano-composites
Lee, Sang-Bok ; Jeong, Bo-Hwa ; Yi, Jin-Woo ; Lee, Won-Oh ; Um, Moon-Kwang ;
Polymer Korea, volume 35, issue 1, 2011, Pages 60~65
In order to maximize the performance of polymer nano-composites, it is essential to understand an effect of a dispersion state on material properties as well as to achieve highly dispersed composites. In this work, a simple quantitative approach to evaluate the degree of dispersion was suggested for carbon nanotube (CNT) embedded polymer nano-composites. Through UV-visible spectroscopy analysis, the transmittance of nano-composites was measured at various dispersion states and it was found that the transmittance reduced as the dispersion state of CNT improved. Based on the results, an effective concentration factor for quantitative evaluation of dispersion state was introduced into the Beer-Lambert transmittance law. The proposed method and parameter to evaluate the degree of dispersion were verified by analyzing the transmittances at different dispersion states of CNT, concentrations of CNT and sample thicknesses.
Synthesis of Hyper Crosslinked Polymer Particle Having Hydroxyl Group
Jeon, Hyo-Jin ; Kim, Dong-Ok ; Park, Jea-Sung ; Kim, Jong-Sik ; Kim, Dong-Wook ; Jung, Mi-Sun ; Shin, Seong-Whan ; Lee, Sang-Wook ;
Polymer Korea, volume 35, issue 1, 2011, Pages 66~71
With the synthesis of hyper crosslinked polymer particle (HCPP), having microporous structure with hydroxyl functional group, synthesized via polymerization reaction consists of three stepssuspension polymerization, hyper crosslinking by Friedel-Craft catalysis and hydrolysis reaction, the effects of the ratio of each monomer, hyper crosslinking conditions and
supercritical drying on the variations of surface morphology, pore size & distribution and BET surface area of HCPP have been investigated. It was observed that the formation of surface crack or fracture of HCPP was intimately related with the degree of hyper crosslinking reaction between microphase separated domains. And the value of BET surface area of HCPP increased with the increase of reaction temperature, time and the amounts of solvent used in hyper crosslinking step. Moreover,
supercritical drying was proven to be a very effective method for removing stabilizer, unreacted monomers and oligomers from HCPP but needed to add methanol as a co-solvent for efficient removing of residual catalyst.
The Crosslinking Characteristic of Poly(vinyl alcohol) by Natural Dye
Kim, Gwan-Hoon ; Kim, Hyo-Gap ; Kang, Ho-Jong ;
Polymer Korea, volume 35, issue 1, 2011, Pages 72~76
The physical properties of crosslinked poly(vinyl alcohol)(PVA) by natural dyes as crosslinking agents were investigated and a comparison was made with chemically crosslinked PVA by Polycup 172. It was found that natural anthocyanin and crocin made possible to crosslink PVA physically through the hydrogen bonding of OH in both PVA and natural dyes in the present with NaCl as a catalyst. The water swellability dramatically decreased and the physical crosslinking led to decreasing of crystallinity of PVA. The lowering of thermal stability was noticed in the physically crosslinked PVA compared to chemically crosslinked PVA due to its lower crosslink density. However even natural dyes have polysaccharides in their chain, their thermal stability was higher than uncrosslinked PVA.
Effects of Structure of the Bridge on Polymerization Behavior of Dinuclear Constrained Geometry Catalysts and Properties of Ethylene-Styrene Copolymers
Pham, Nhat Thanh ; Nguyen, Thi Dieu Huyen ; Thanh, Nguyen Thi Le ; Noh, Seok-Kyun ;
Polymer Korea, volume 35, issue 1, 2011, Pages 77~86
Polymerization properties of six dinuclear constrained geometry catalysts (DCGC) were investigated. The different length bridges of three catalysts were para-phenyl (Catalyst 1), para-xylyl (Catalyst 2), and para-diethylene phenyl (Catalyst 6). The other three DCGC have the same para-xylyl bridge with the different substituents at the phenyl ring of the bridge. The selected substituents were isopropyl (Catalyst 3), n-hexyl (Cataylst 4), and n-octyl (Catalyst 5), It was found that the longer catalyst not only exhibited a greater activity but also prepared a higher molecular weight copolymer. The catalyst 3 having a bulky isopropyl substituent revealed the lower activity but formed the highest molecular weight polymer comparing with the other alkyl substituted DCGCs. These results were able to be understood on the basis of the electronic and steric characteristics of the bridge. This study confirms that the control of the bridge structure of DCGC may contribute to control the microstructure of polymers.
Synthesis of Fluorene-containing Photosensitive Polymer and Its Application to the Carbon Black-based Photoresist for LCD Color-Filter
Kim, Joo-Sung ; Park, Kyung-Je ; Lee, Dong-Guen ; Bae, Jin-Young ;
Polymer Korea, volume 35, issue 1, 2011, Pages 87~93
We developed a fluorene-containing multifunctional binder polymer for LCD color filter resist, and employing the binder polymer, carbon black based black photoresist (CBR) was prepared in order to apply it to the black matrix (BM). To obtain the multifunction of the binder polymer, we synthesized bisphenol fluorene epoxy acrylate-containing unsaturated polyester and identified the binder polymer structure with
NMR, GPC and FTIR. The corresponding BFEA-polyester binder polymer was compared with the commercially available acryl binder toward the application to the CBR. From the BM lithography test, we found that the synthesized BFEA-polyester binder had better photocrosslinking capability and alkali solubility. In addition, the newly developed binder gave a good process margin, good resolution and adhesion property on a glass substrate.
Preparation and Swelling Behavior of Stimuli-responsive PHEMA Hybrid Gels
Ahn, Jung-Hyun ; Jeon, Young-Sil ; Chung, Dong-June ; Kim, Ji-Heung ;
Polymer Korea, volume 35, issue 1, 2011, Pages 94~98
Poly(2-hydroxyethyl methacrylate), PHEMA, hybrid gels containing Pluronic and acrylic acid (AAc) were prepared as new biocompatible and stimuli-responsive hydrogels by photo-polymerization technique. The prepared hybrid gel showed reversible, temperature-responsive swelling behavior due to the presence of Pluronic component, which underwent sol-gel transition at an elevated temperature to cause gel shrinkage. The hydrogel also exhibited increased swelling degrees and pH-sensitivity due to the AAc component with ionizable carboxylic acid groups. The microporous gel morphology and its changes upon stimuli was observed by scanning electron microscopy.