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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Polymer Society of Korea
Editor in Chief :
Volume & Issues
Volume 26, Issue 6 - Nov 2002
Volume 26, Issue 5 - Sep 2002
Volume 26, Issue 4 - Jul 2002
Volume 26, Issue 3 - May 2002
Volume 26, Issue 2 - Mar 2002
Volume 26, Issue 1 - Jan 2002
Selecting the target year
Synthesis and Characterization of New Positive Photosensitive Polyimide Having Photocleavable 4,5-Dimethoxy-2-nitrobenzyl (DMNB) Groups
Polymer Korea, volume 26, issue 6, 2002, Pages 701~709
To synthesize a new positive photosensitive polyimide precursor, parts of carboxylic acid groups in poly (amic acid) were esterified with 4,5-dimethoxy-2-nitrobenzyl bromide in the presence of K
/HMPA followed by the chemical imidization of residual carboxylic acid units. The chemical structure of resulting polymer was characterized by
H-NMR, UV/vis and FT-IR spectroscopic methods, and its thermal properties were examined by DSC and TGA. Upon UV irradiation, 4,5-dimethoxy-2-nitrobenzyl moiety underwent the photodegradation. As a result, the polymer became soluble in alkaline developer due to the formation of carboxylic acid moiety, which was used to make a micron-sized positive pattern. Sensitivity curves were obtained from the gel fraction experiments with respect to the various 4,5-dimethoxy-2-nitrobenzyl ester contents. From those curves, the sensitivity was ranged iron 4000 to 6000 mJ/㎠, and the contrast was measured to be from 3.1 to 4.9.
Preparation of Molecularly Imprinted Poly(methacrylic acid) and Its HPLC Separation Characteristics of Retinoids
Polymer Korea, volume 26, issue 6, 2002, Pages 710~717
Molecularly imprinted polymers were prepared in particle forms by crosslinking methacrylic acid (MAA)) using all trans-retinoic acid as a template. The HPLC column packed with the prepared molecular imprinted polymers showed high capability in separation of retinoid derivatives. The column capacity factor and selectivity increased with increasing MAA to template ratio when the incorporated template amount was fixed, as it statistically generated more binding sites between host molecules and template. Molecularly imprinted polymer particles prepared via an emulsion polymerization method were round-shaped and their sizes were more uniformly distributed, but their separation capability was inferior to those obtained by solution polymerization method. It was presumably because the loss of interaction strength between MAA and the template due to hydrogen bonding either between MAA and water or between template and water during the synthesis of molecularly imprinted polymers.
Effects of Ar+ ion Beam Irradiation on the Adhesion Forces between Carbon fibers and Thermosetting Resins
Polymer Korea, volume 26, issue 6, 2002, Pages 718~727
In this work, an Ar+ beam was irradiated on carbon fiber surfaces to improve the interfacial shear strength (IFSS) of the resulting composites using an ion assisted reaction (IAR) method h single fiber pull-out test was executed to investigate the basic characteristics of the single Carbon fiber/matrix interface. Based on Greszczuk's geometrical model, the debonding force for pull-out of the fiber from the resins was discussed with the applied ion beam energy as a result, it was known that an ion beam treatment produced the functional groups on fiber surface and etching lines along the fiber axis direction, resulting in increasing the adhesion forces between fibers and matrix, which caused the improvement of the IFSS in a composite system. And, it was also found that the maximum IFSS was shown at 0.8 keV ion beam energy in this system.
Dielectric Characterization of Unsaturated Polyester Curing
Polymer Korea, volume 26, issue 6, 2002, Pages 728~736
The thermal and dielectric properties of unsaturated polyester resin system during cure were analyzed under Isothermal conditions. Both
" decreased and dipole relaxation was observed under isothermal conditions during cure. The ionic conductivity decreased linearly with the conversion according to the Kienle-Rate equation (ln(
) up to
=0.15, after which it aparted from the relationship due to the entanglement of polymer chains. The effect of ionic conductivity was revealed to be larger than that of dipole motion during the whole cure through the electrical modulus analysis. Although dielectric motion was analyzed with Debye model, it was observed only at a narrow time region of middle stage of cure. In order to estimate the dielectric properties during the whole cure, the Havriliak-Negami model was considered and modified with the strong effect of ionic conductivity. The changes of
" were well estimated with this modified Havriliak-Negami model.
DSC and FTIR Studies of Miscible Poly(butylene 2,6-naphthalate)/Poly(4-vinylphenol) Blends
Polymer Korea, volume 26, issue 6, 2002, Pages 737~744
Thermodynamic miscibility of the binary blends composed of semi-crystalline poly (butylene 2,6-naphthalate) (PBN) and amorphous poly (4-vinylphenol) (PVPh) was investigated using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. DSC scan results showed that there was a single glass transition temperature (T
g/) for each blend. Crystalline melting temperature (T
m/) depression of the PBN in the blends was also observed with the increase of PVPh content. Both results of the single T
g/ and the depression of T
m/ for the PBN/PVPh blends indicate that the blends are thermodynamically miscible at the molecular level. FTIR spectroscopic analysis confirmed that strong intermolecular hydrogen bonding interactions between the ester carbonyl groups of the PBN and the hydroxyl groups of the PVPh are occurred.
Polarized Raman Spectroscopic Studies of Syndiotactic Polypropylene
Polymer Korea, volume 26, issue 6, 2002, Pages 745~751
The anisotropic Raman scattering properties of oriented syndiotactic poly propylene have been investigated using FT-Raman spectrometer in which the fluore scent problem of polymer samples can be removed. To assign the observed Raman bands to their respective symmetry species, the anisotropic scattering results for four different combinations of incident and scattered polarization were compared with those predicted by normal coordinate analysis and infrared dichroism measurement data.
Vibrational Spectroscopic Studies of Crystallization in Mixed n-Paraffins
Polymer Korea, volume 26, issue 6, 2002, Pages 752~758
FTIR, FT-Raman, and X-ray diffraction techniques were used to determine chain segregations and lamellar structures of the mixed binary n-paraffins with different chain lengths. The results of three different techniques, infrared spectroscopic studies of crystal field splitting, the Raman longitudinal acoustic mode, and the SAXS long period measurements were compared one another to understand the crystallization mechanism of separated or mixed n- paraffin lamellae.
Morphology and Properties of Microcellular foams by High Infernal Phase Emulsion Polymerization: Effect of Emulsion Compositions
Polymer Korea, volume 26, issue 6, 2002, Pages 759~766
Regular, spherical and isotropic open-microcellular foams having low density were prepared by the high internal phase emulsion (HIPE) polymerization mainly composed of styrene monomer and water The effects of Polymerization conditions. such as the content of water, divinylbenzene as a crosslinking agent and dodecane as a chain transfer agent, were investigated based on the tell size and foam properties. The microstructural morphology was observed using scanning electron microscopy (SEM) and the compression modulus of the foam was evaluated using compression test. The dropwise feeding of the aqueous phase into the oil phase was more effective than the batch feeding in producing the uniform and stable foam. Agitation speed and surfactant strongly influenced on the cell size and the window size between water droplets. Introduction of chain transfer agent increased the cell size, whereas it decreased the window size. Compression modulus increased with the crosslinking agent, but decreased with the chain transfer agent.
Studies on Cure Behavior and Rheological Properties of Tetrafunctional Epoxy/Biodegradable MAP Blends
Polymer Korea, volume 26, issue 6, 2002, Pages 767~777
In this work, biodegradable modified aliphatic polyester (MAP) in tetrafunctional epoxy (4EP) resin was investigated in terms of cure kinetics, thermal stabilities, rheological properties, and mechanical interfacial properties. DSC results of the blends show that the cure activation energies (E
a/) were increased in 10 wt% of MAP compared with neat 4EP, due to the increasing intermolecular interaction between 4EP and MAP. The decomposed activation energies (E
t/) derived from Coats-Redfern method, were increased within the 10∼30 wt% composition range of MAP contents, resulting from increasing the cross-linking density of the blend system. Rheological properties of the blend system were investigated under isothermal condition using a rheometer. Cross-linking activation energies (E
c/) were determined from the Arrhenius equation based on gel time and curing temperature. As a result, the E
c/ showed a similar behavior with E
a/. The fracture toughness (K
IC/) of the mechanical interfacial properties was discussed in semi-IPN behaviors of the casting specimen.
A Study on the Preparation of Dextran Film and Its Modification
Polymer Korea, volume 26, issue 6, 2002, Pages 778~784
Chemical modification of a dextran film to improve its physical properties was carried out by addition of plasticizers and crosslinking agents. Moreover, low-temperature plasma treatment with acetylene gas was done. The dextran film showed high mechanical strength but was brittle and vulnerable to moisture. When plasticizer was added, it became very soft but with large reduction of mechanical strength. However, a flexible film with fairly high mechanical strength and water resistance was prepared when the film was crosslinked by adding crosslinking agent with or after the addition of plasticizer. Treatment with an acetylene plasma changed the dextran film surface from hydrophilic to hydrophobic with little influence on the bulk properties of the film.
Characterization of ion-conductive Behaviors for Crystalline/Amorphous Solid Polyether Electrolytes Using Supercritical
;Y. Tominaga;S. Asai;M. Sumita;;
Polymer Korea, volume 26, issue 6, 2002, Pages 785~791
The effect of the supercritical carbon dioxide (sc
) on ion-conductive behaviors for polyether electrolytes based on, both poly (ethylene oxide) (PEO) and poly [oligo (oxyethylene glycol) methacrylate] (PMEO) with lithium triflate, LiCF
, has been investigated. In particular, the present research is a new concept for improving the ionic conductivity of polyether electrolytes. The maximum ionic conductivity (
) at room temperature of the PEO electrolyte was more than 100 times higher, and the
of the PMEO electrolyte was 30 times improved by the se
treatment, respectively. It was revealed that the penetration of
molecules into the polymer matrix causes the increase of carrier ions by ion-dispersion effect and the decrease of glass transition temperature (T
) by plasticizing effect that results in the improvement of the ion transport behaviors.viors.
Preparation and Characterization of Poly(vinyl alcohol)/Poly(N-vinylpyrrolidone)/Glycerin/Chitosan Hydrogels by Radiation
Polymer Korea, volume 26, issue 6, 2002, Pages 792~802
In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.
Effect of Mixing Process on the Wear Properties of UHMWPE/Kaolin Composite
Polymer Korea, volume 26, issue 6, 2002, Pages 803~811
In this study the wear behavior of ultra high molecular polyethylene (UHMWPE) filled with kaolin particles by different methods was investigated. UHMWPE/kaolin composites were prepared by two different methods: polymerization-filling and powder mixing. Particularly in a powder mixing method. Particle dispersion and wear property according to powder mining method were examined. It was found from wear test that filling of inorganic filler into UHMWPE by polymerization filling was more effective way than by powder mixing method in improving Wear resistance of UHMWPE. It was also confirmed that abrasive wear was dominant wear mechanism and particle dispersion in the composite as well as interface property was an important factor in controlling the wear behavior of the resulting composites.
A Study on the PTC Thermistor Characteristics of Polyethylene and Polyethylene Copolymer Composite Systems in Melt and Solution Manufacturing Method
Polymer Korea, volume 26, issue 6, 2002, Pages 812~820
The positive temperature coefficient (PTC) characteristics of polymer composites were investigated with the nano-sized carbon black particles using solution tasting and melt compounding methods. The polymeric PTC composites should the electrical threshold at 35 wt% for the melt compounding method and 40 wt% for the solution casting method. The ethylene vinylacetate copolymer (EVA) composite showed a gradual increase of resistance as a function of temperature and showed a maximum at the polymer molting point. The resistance of the high-density polythylene (HDPE) composite remains unchanged with temperature but started to Increase sharply near the melting point of HDPE and showed a maximum resistance at the melting point of HDPE. The dispersion of nano-sized carbon black particles was investigated by scanning electron microscopy (SEM) and low resistance after electrical threshold, and both methods exhibited a well dispersed morphology. When the electric current was applied to the PTC composites, the resistance started increasing at the curie temperature and further increased until the trip temperature was roached. Then the resistance remained stable over the trip temperature. The secondary increase started at T
m/ of matrix polymer and kept increasing up to the trip temperature.
Effect of Added Pluronics on fabrication of Poly(L-lactic acid) Scaffold via Thermally-Induced Phase Separation
Polymer Korea, volume 26, issue 6, 2002, Pages 821~828
Regular and highly interconnected macroporous poly(L-lactic acid) (PLLA) scaffolds with pore size of 10∼300 ㎛ were fabricated through thermally induced phase separation of a PLLA-dioxane-water ternary system in the presence of a small amount of Pluronics. Addition of Pluronics to the ternary system raised the cloud-point temperature curve in the order of P-123< F-68< F-127. The Pluronics act as nuclei for the phase separation. This assistance is enhanced with increasing length of the hydrophilic PEO blocks in the Pluronics molecules. Liquid-liquid spinodal phase separation was induced at higher temperatures in the systems containing Pluronics because the spinodal region is raised to higher temperature. The absorption of Pluronics onto the interface stabilizes a macro scale structure and increases the interconnection of pores.