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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 32, Issue 6 - Nov 2008
Volume 32, Issue 5 - Sep 2008
Volume 32, Issue 4 - Jul 2008
Volume 32, Issue 3 - May 2008
Volume 32, Issue 2 - Mar 2008
Volume 32, Issue 1 - Jan 2008
Selecting the target year
A Study on Emulsion Copolymerization of
-Diacrylate Poly(dimethylsiloxane) Containing Vinyl Ester of Versatic Acid/Vinyl Acetate
Naghash, Hamid Javaherian ; Mallakpour, Shadpour ; Forushani, Parivash Yavari ; Uyanik, Nurseli ;
Polymer Korea, volume 32, issue 2, 2008, Pages 95~102
-diacrylate poly(dimethylsiloxane) (DA-PDMS) containing vinyl ester of versatic acid/vinyl acetate (Veova-10/VAc) was prepared by emulsion copolymerization of (DA-PDMS), Veova-10 (with VAc), and auxiliary agents at
in the presence of ammonium peroxodisulfate (APS) as an initiator. Sodium dodecyl sulfate (SDS) and nonylphenol ethylene oxide-40 units (NP-40) were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FT-IR). Thermal properties of the copolymers were studied by using thermogravimetric analysis(TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of variables such as temperature, agitation speed, surfactant kinds, molecular weights, initiator, and DA-PDMS concentrations on the properties of the silicone-containing Veova-10/VAc emulsions were examined. The calculation of monomer conversion versus time histories indicates that by increasing the DA-PDMS concentration the polymerization rate and the number of polymer particles decrease, respectively.
The Effect of Sodium Alginate of Osmotic Pellet on Drug Release
Youn, Ju-Yong ; Ku, Jeong ; Lee, Soo-Young ; Kim, Moon-Suk ; Lee, Bong ; Khang, Gil-Son ; Lee, Hai-Bang ;
Polymer Korea, volume 32, issue 2, 2008, Pages 103~108
Osmotic pellet, which consisted of water-swellable seed layer, drug layer, and porous membrane layer, has been widely utilized in oral drug delivery system. In this work, we describe the preparation of osmotic pellet with nifedipine as model drug and a mixture of cellulose acetate (CA) and Eudragit RS as membrane layer, and then examined the drug release behavior on the variation of the thickness change of membrane layer (CA and Eudragit RS) and release media. Furthermore, we examined the nifedipine release behavior using sodium alginate as a potential membrane candidate. Osmotic pellet was obtained in the quantitative yield by fluidized bed coater. Osmotic pellet exhibited the round morphology and the size ranging
in SEM. The nifedipine release decreased as the thickness of membrane layer (CA and Eudragit RS) increased. In addition, it observed that there is difference of release amount in between intestinal juice (pH 6.8) and gastric juice (pH 1.2). In the case of osmotic pellet coated with sodium alginate, nifedipine release behavior depended on the crosslinking of sodium alginate layer. In conclusion, we found that various membrane layers could control the release amount of nifedipine.
Effect of 2-D DBP/PLGA Hybrid Films on Attachment and Proliferation of Intervertebral Disc Cells
Ko, Youn-Kyung ; Jeong, Jae-Soo ; Kim, Soon-Hee ; Lim, Ji-Ye ; Rhee, John-M. ; Kim, Moon-Suk ; Lee, Hai-Bang ; Khang, Gil-Son ;
Polymer Korea, volume 32, issue 2, 2008, Pages 109~115
Because demineralized bone particle (DBP) contains various bioactive molecules such as cytokines, it is widely used biomaterials in the field of tissue engineering. In this study, we investigated the effect of 2-dimensional DBP/PLGA hybrid films on adhesion, proliferation and phenotype maintenance of intervertebral disc cells. PLGA films incorporated with different amount (0, 10, 20, 40 and 80 wt%) of DBP were prepared by the solvent evaporation method and characterized by scanning election microscopy (SEM). PLGA film has a flat and smooth surface. According to the increase of content of DBP, the surface of DBP/PLGA film exhibited few agglomerates and increased the roughness of the surface. Annulus fibrosus (AF) and nucleus pulposus (NP) cells were cultured on PLGA and DBP/PLGA film surface, and then examined the cell adhesion and proliferation by the cell count and SEM observation. The result of cell count and SEM observation revealed that 10 and 20% DBP in DBP/PLGA films were superior to adhesion and proliferation of both AF and NP cells. We confirmed that specific gene expression of disc cells on DBP/PLGA film based on the cell count result. Disc cells seeded on 20% DBP/PLGA film expressed the gene of type I and II collagen continuously. Therefore, pertinent content of biomaterials could provide more appropriate condition on adhesion and proliferation of cell. And this results may be used as a basic data for the intervertebral disc regeneration using tissue engineering.
Thermal and Rheological Properties, and Biodegradability of Chemically Modified PLA by Reactive Extrusion
Jang, Woo-Yeul ; Hong, Ki-Heon ; Cho, Baek-Hee ; Jang, Sang-Hee ; Lee, Sang-Il ; Kim, Bong-Shik ; Shin, Boo-Young ;
Polymer Korea, volume 32, issue 2, 2008, Pages 116~124
A commercialized biobased and biodegradable poly(lactic acid)(PLA) containing the functional monomer of glycidyl methacrylate (GMA) was chemically modified using reactive extrusion to enhance its melt strength. Modified PLAs were prepared with various contents of GMA and initiator, and were characterized by observing their gel fraction, thermal properties, melt viscoelasticity and biodegradability. The complex viscosity and storage modulus of chemically modified PLA with the initiator alone was increased by addition of initiator and were more increased in the presence of GMA. There was a optimum content of GMA showing the maximum complex viscosity with the amount of initiator. The biodegradebility of modified PLA was slightly decreased by addition of GMA.
Flame Retardant Synergistic Performance between Cyclic Diphosphonate Ester and Melamine in Polyamide 6
Wang, Xueli ; Jiang, Jianming ; Yang, Shenglin ; Jin, Junhong ; Li, Guang ;
Polymer Korea, volume 32, issue 2, 2008, Pages 125~130
A commercial cyclic diphosphonate ester (TPMP) and melamine (MA) was combined and added to polyamide 6 (PA6) to prepare the fire retardant PA6. An increase of the oxygen index to 28.6 as well as an improvement of the UL-94 classification to V-0 rating was observed. Cone measurements explained the rate of heat release (RHR) decreased and TGA showed the early decomposition and high solid residue due to co-addition of TPMP and MA, suggesting the occurrence of synergistic effect of TPMP and MA on fire resistance of PA6. The morphology of the char developed during combust ion showed the appearance of thick, intumescent cells on the surface of retardant PA6, which protects the underlying material from the action of the heat flux or flame and limits the diffusion of combustible volatile products towards the flame and oxygen.
3-D Rat Hepatocytes' Culture on Polystyrene Nanofibrous Scaffold
Kim, Young-Jin ; Ahn, Chang-Hyun ; Oh, Hwan-Hee ; Kim, Young-Jin ; Yoon, Kwan-Han ; Kang, Inn-Kyu ; Kwon, Oh-Hyeong ;
Polymer Korea, volume 32, issue 2, 2008, Pages 131~137
We have fabricated polystyrene (PS) nanofibrous scaffold for hepatocyte culture by electrospinning method and subsequently coated with specific ligand of Poly[N-p-vinylbenzyl-O-
)-D-gluconamide](PVLA) to enhance hepatocytes attachment. Rat hepatocytes behavior on the PVLA-coated and non-coated PS nanofibrous matrices have been investigated. Electrospun PS nanofiber structures revealed randomly aligned fibers with average diameter of 500 nm. It is observed that PS nanofibrous matrix could incorporate many cells into the interior of the matrix probably due to the suitable pore size. Cell viabilities cultured on PVLA-coated PS nanofibrous mats were maintained for 3 weeks, while it was decreased rapidly on PVLA-coated PS dishes. High hepatic functions especially for albumin secretion and ammonia removal were maintained at least for 2 weeks on nanofibrous mats but rapidly decreased on flat PS dishes. These results indicate that nanofibrous structure enabled 3-D culture with high level of cell-cell contact results in providing cell-cell communications and subsequent long-term maintenance of specific cell functions.
Synthesis and Characterization of Theophylline Molecularly Imprinted Polymers
Ryu, Ho-Sik ; Kim, Beom-Soo ; Kim, Dae-Su ;
Polymer Korea, volume 32, issue 2, 2008, Pages 138~142
Molecularly imprinting technology is an effective method to prepare a synthetic material with a high selectivity to a target molecule. In this study, a molecularly imprinted polymer (MIP) was synthesized via UV-polymerization using theophylline and UV-curable polyester-acrylate resin as a template molecule and a crosslinker, respectively. To elucidate the effects of functional monomer type on the performance of the MIP, each MIP was synthesized using mathacrylic acid, acrylic acid, and acryl amide as functional monomers. Each MIP showed higher rebinding capacity to theophylline than its corresponding non-imprinted polymer (NIP). The MIP synthesized using mathacrylic acid as a functional monomer showed the highest rebinding capacity to theophylline. The selectivity of the MIP was investigated using a solution with caffeine having a very similar structure to theophylline. The binding performance of the MIP to theophylline decreased when distilled water was used as a solvent, which has more polarity than chloroform.
Preparation and Characterization of PEG-PLA(PLGA) Micelles for Solubilization of Pioglitazone
Im, Jeong-Hyuk ; Lee, Yong-Kyu ; Huh, Kang-Moo ;
Polymer Korea, volume 32, issue 2, 2008, Pages 143~149
We synthesized PEG-PLA (or PLGA) amphiphilic di-block copolymers, which consist of PEG as biocompatible and hydrophilic block and PLA (or PLGA) as biodegradable and hydrophobic block, by ring opening polymerization of LA in the presence of methoxy PEG as a macroinitiator. The compositions and the molecular weights of the copolymers were controlled by changing the feed ratio of LA (and GA) to PEG initiator. The di-block copolymers could self-assemble in aqueous media to form micellar structure. A hydrophobic model drug, pioglitazone, was loaded into the polymer micelle using solid dispersion and dialysis methods, and the drug-loaded micelles were characterized by AFM, DLS and HPLC measurements. The drug loading capacity and in vitro release studies were performed and evaluated under various conditions. These results indicated that the amphiphilic di-block copolymers of PEG-PLA (or PLGA) could solubilize pioglitazone by solid dispersion method and the drug release was modulated according to micellar chemical compositions.
Kinetic Study of Cyclization of High-Tacticity Polyacrylonitrile Heat-Treated under Air Atmosphere via XRD
Xu, Zhi-Xian ; Xu, Jing ; Xu, Liang-Hua ; Dai, Yong-Qiang ; Xue, Li-Wei ; Jin, Ri-Guang ;
Polymer Korea, volume 32, issue 2, 2008, Pages 150~156
Two different polyacrylonitrile samples (PANs, triad tacticity fraction is 0.25 and 0.64) were synthesized and used to study the kinetics of cyclization. Polymers were treated at different temperatures between 250 to
under air atmosphere, and analyzed by X-ray diffractometer. The sharp and strong peak at
corresponds to a lateral repeat distance that is the (100) diffraction in hexagonal lattice, while the peak at
reflects the (101) diffraction. In comparing their areas of different heat treated samples, the cyclization of both PANs was identified as a first-order reaction. The rate constants of cyclization reaction at different temperatures and the active energy parameter were obtained. This results might provide an important effect on pre-oxidation of polyacrylonitrile fiber.
Distribution Characteristics of Pyrolysis Products of Polyethylene
Lee, Dong-Hwan ; Choi, Hong-Jun ; Kim, Dae-Su ; Lee, Bong-Hee ;
Polymer Korea, volume 32, issue 2, 2008, Pages 157~162
To investigate the characteristics of pyrolysis for LDPE, LLDPE and HDPE, the low temperature pyrolysis was carried out in the range of 425 to
for 35 to 65 min. The liquid products formed during pyrolysis were classified into gasoline, kerosene, light oil and wax according to the distillation temperatures based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. TGA experiments for three PE samples showed that the onset temperature of pyrolysis increased with increasing heating rate, and the onset temperature of pyrolysis at a fixed heating rate was in the order of LDPE
. Yields of gasoline and kerosene were highest at
, 65 min and decreased slightly at above
Fabrication of Tailor-Made 3D PCL Scaffold Using a Bio-Plotting Process
Son, Joon-Gon ; Kim, Geun-Hyung ; Park, Su-A ; Kim, Wan-Doo ;
Polymer Korea, volume 32, issue 2, 2008, Pages 163~168
Biomedical scaffold for tissue regeneration was fabricated by one of rapid prototyping processes, bioplotting system, with a biodegradable and biocompatible poly(
-carprolactone)(PCL). Through dynamic mechanical test, it was observed that the PCL scaffold manufactured by the bioplotting process has the superior mechanical properties compared to the conventional scaffold fabricated by a salt-leaching process, and the plotted scaffold could be employed as a potential scaffold to regenerating hard and soft tissue. The plotted scaffold was consisted of porous structures. which were interconnected with each pore to help cells be easily adhered and proliferated in the wall of pore tunnels, and metabolic nutrients can be transported within the matrix. By using the plotting system, we could adjust the pore size, porosity, strand pitch, and, strand diameter of PCL scaffolds, which were important parameters to control mechanical properties of the scaffolds, and consequently we could determine that the mechanically controlled scaffolds could be used as a matching scaffold for any required mechanical properties of the target organ. The fabricated 3D PCL scaffold showed enough possibility as a 3D biomedical scaffold, which was cell-cultured with chondrocytes.
Thermotropic Liquid Crystalline Properties of Cholesteryloxycarbonated and (Cholesteryloxycarbonyl) alkanoated Celluloses
Jeong, Seung-Yong ; Ma, Yung-Dae ;
Polymer Korea, volume 32, issue 2, 2008, Pages 169~177
The thermal and optical properties of cellulose tri(cholesteryloxy) carbonate(CCE0) and cellulose tri(cholesteryloxycarbonyl)alkanoates (CCEn,
, 10, the number of methylene units in the spacer) were investigated. CCE0 formed an enantiotropic cholesteric phase, whereas all the CCEn exhibited monotropic cholesteric phases. CCEn with n=
formed cholesteric phases with left-handed helical structures whose optical pitches (
) decrease with increasing temperature. On the other hand, CCE0 and CCEn with n=2 or 10 did not display reflection colors over the full cholesteric range, suggesting that the helical twisting power of the cholesteryl group highly depends on the length of the spacer connecting the cholesteryl group to the main chain. The thermal stability and degree of order in the mesophase and the temperature dependence of the
observed for CCEn highly depended on n. The results were discussed in terms of the differences in the internal plasticization, the arrangement of the side groups, and the conformation of the molecules.
Preparation and Properties of Cellulose Diacetate/
Lim, Hwan-Kyu ; Kye, Hyoung-San ; Won, Sung-Ho ; Nam, Jae-Do ; Lee, Young-Kwan ;
Polymer Korea, volume 32, issue 2, 2008, Pages 178~182
Cellulose diacetate (CDA) and calcium carbonate (
) biodegradable composites were prepared by melt mixing in a twin screw extruder and their physical properties were examined. In the melt processing, triacetine and epoxidized soybean oil were added to the composites as a plasticizer and lubricant, respectively. The optimal conditions for the preparation of the biodegradable composites were determined. Acetic acids (
) were made by pyrolysis acetyl group (
) of CDA and TA in melt processing. Increasing the amount of
in the composites resulted in further enhancement of the
absorption effects. The tensile strength and elongation were decreased, and Young's modulus and
value increased with increasing amount of
Reinforced Polymer/Clay Nanocomposite Foams with Open Cell Prepared via High Internal Phase Emulsion Polymerization
Song, In-Hee ; Kim, Byung-Chul ; Lee, Seong-Jae ;
Polymer Korea, volume 32, issue 2, 2008, Pages 183~188
Reinforced open cell micro structured foams were prepared by the polymerization of high internal phase emulsions incorporating inorganic thickeners. Organoclays were used as oil phase thickener, and sodium montmorillonite was used as aqueous phase thickener. Rheological properties of emulsions increased as oil phase thickener concentration and agitation speed increased, due to the reduced drop size reflecting both competition between continuous and dispersed phase viscosities and increase of shear force. Drop size variation with thickener concentration could be explained by a dimensional analysis between capillary number and viscosity ratio. Upon the foams polymerized by the emulsions, compression properties, such as crush strength and Young's modulus were measured and compared. Among the microcellular foams, the foam incorporated with an organoclay having reactive group showed outstanding properties. It is speculated that the exfoliated silicate layers inside polystyrene matrix, resulting in nanocomposite foam, are the main reason why this foam has enhanced properties.
Fluorescent Crack Sensor in a Polymeric Material
Cho, Sung-Youl ; Kim, Ji-Eun ; Kim, Joong-Gon ; Chung, Chan-Moon ;
Polymer Korea, volume 32, issue 2, 2008, Pages 189~192
A styrylpyrylium salt (DHSP) was synthesized and then photodimerized to obtain a cyclobutane-type dimer (DHSP dimer). Methacryloyl group was incorporated into DHSP dimer to obtain DMSP dimer. Based on FT-IR analysis of a crosslinked DMSP dimer, it was considered that the cyclobutane structure reversed to styryl C=C bonds upon crack formation. Fluorescence measurement of DHSP in solid state (excitation at 385 nm) showed emission centered at 626 nm, while DHSP dimer revealed very weak emission. Fluorescent emission from microcracks in a film of crosslinked DMSP dimer was observed upon exposure to