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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
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Liquid Crystalline Aromatic Polyesters
Kwon Young-Wan ; Choi Dong Hoon ; Jin Jung-Il ;
Polymer Korea, volume 29, issue 6, 2005, Pages 523~535
Linear aromatic polyesters are representative examples of thermotropic liquid crystalline polymers (TLCPs), which have been the subject of many researches. This article reviews the structure-LC properties relationship in wholly aromatic CLCPs mostly based on the results obtained for the past quarter of a century. Especially, this review deals with the structural details of aromatic polyester TLCPs that influence the liquid crystalline and thermal properties. In the last part of this article the liquid crystalline properties of combined type and hyperbranched polyester also are discussed. Introduction to various synthetic methods are included in the last section.
Effect of Time-Related Parameters on Rockwell Hardness Measurement
Bahng Gun Woong ; Tak Nae-Myung ;
Polymer Korea, volume 29, issue 6, 2005, Pages 536~542
The effect of lime-related parameters such as loading velocity, load application time, gauge reading time on Rockwell hardness measurement was investigated for PE, PP PVC, and PMMA. It was found that keeping the specific requirements in the same condition is very important to obtain reliable and repeatable darn in polymer hardness measurement. The optimum condition for hardness measurement was 4 sec for load application time,15 sec for test load application net time, and 15 sec for gauge reading time after unloading. Using thess conditions, round robin test was carried out for 6 laboratories and it was shown that the testing machine should be one in which time-related variables are controllable. Indirect verification of hardness tester using brass reference block was not enough to guarantee the test results for polymer.
Fabrication of PLGA/Dextran Double-Layered Microspheres by Oil-in-Water Solvent Evaporation Method
Ko Jong Tae ; Lee Jae-Ho ; Lee Chang-Rae ; Shin Hyung Sik ; Yuk Soon Hong ; Kim Moon Suk ; Khang Gilson ; Rhee John M. ; Lee Hai Bang ;
Polymer Korea, volume 29, issue 6, 2005, Pages 543~548
Double-layered spheres play an important role in controlling drug delivery for pharmaceutical application, because of the low initial burst compared with single-layered spheres and targetable delivery to specific organ. But it has drawback in loading drug and controlling size. In this study, we developed double-layered spheres using relatively simple oil-in-water (O/W) solvent evaporation method witw/without ultrasonication and investigated the size variation of the double-layered microspheres on the contents of poly(lactide- co-glycolide) (PLGA). Double - layered spheres were char-acterized by scanning elecron microscope (SEM), camscope, and confocal fluorescence laser microscope (CFLM). Double-layered spheres showed smooth surfaces and obvious difference between core and corona by SEM observation and camscope. We observed the fluorescent core in the double-walled spheres composed of FlTC-dextran and PLGA using CFLM. It was found that the core of the microsphere was dextran and the corona of the fabricate microsphere was PLGA. Also, the more PLGA concentration, the more the size of the fabricating double-layered sphere observed.
Numerical Analysis of the Non-Isothermal Heat Transfer in Solids Conveying Zone of a Single Screw Extruder
Ahn Young-Cheol ;
Polymer Korea, volume 29, issue 6, 2005, Pages 549~556
Effects of the dimensionless variables on the heat transport phenomena in the extrusion process of a single screw extruder have been studied numerically. Based on the understanding of the solids conveying related to the geometrical structure and characteristics of the screw, the heat balance equation for the solids conveying zone was established and normalized. The finite volume method and power-law scheme were applied to derive a discretized equation and the equation was solved using the alternating direction iterative method with relaxation. Effects of the dimensionless parameters, Biot and Peclet numbers, that define the heat transfer characteristics of the solids conveying zone have been investigated with respect to the temperature of the feeding zone and the length of the solids conveying zone. As the Biot number is increased, the heat loss by cooling dominates to decrease the temperature of the barrel but it has little effects on the temperature of the solids bed and the length of the solids conveying zone. On the other hand, if the Peclet number is increased, the convection term dominates to decrease the temperature of the solids bed and it results in an increase in the length of the solids conveying zone.
Physical Properties and Foaming Characteristics of Poly(butylene adipate-co-succi nate)/Thermoplastic Starch Blends
Kim, Sang-Woo ; Park, Joon-Hyun ; Kim, Dae-Jin ; Lim, Hak-Sang ; Seo, Kwan-Ho ;
Polymer Korea, volume 29, issue 6, 2005, Pages 557~564
Thermoplastic starch (TPS) was manufactured and blended with poly(butylene adipate-co-succinate) (PBAS), which is one of the most popular biodegradable aliphatic polyesters. The effects of the TPS contents on the mechanical properties, thermal characteristics, and biodegradability of PBAS/TPS blends were investigated. The foaming characteristics of those were also studied. With small amount of TPS, mechanical properties of the blends were largely deteriorated and the variations of them decreased with more addition of TPS. In addition, TPS decreased crystallinity and thermal decomposition temperature of PBAS. The PBAS/TPS foam having maximum blowing ratio was obtained with 20 Phr of TPS, and their blowing ratio decreased with the further increase of TPS.
Processing Characteristics of Nylon 6 by Controlling the Melt Viscosity
Kim Hyogap ; Kim Jun Kyung ; Lim Soonho ; Lee Kunwong ; Park Min ; Kang Ho-Jong ;
Polymer Korea, volume 29, issue 6, 2005, Pages 565~570
Melt processing characteristics of nylon 6 (N6) has been investigated by controlling the melt viscosity in melt impregnation process. Calcium stearate (CaST) was introduced as a lubricant for N6 and the melt viscosity of N6 decreased with adding only 1 wt
of CaST. In addition, reactive blending with polycaprolactone (PCL) was carried out by lowering the melt viscosity in N6. It was found that the melt viscosity of N6 could be controlled and further melt viscosity drop could be obtained by applying phenyl phosphite (PP) and diphenyl phosphite (DPP) to enhance the transesterification between N6 and PCL. Our approaches show that the melt viscosity of N6 could be reduced without loss of thermal stability which is the critical problem in high temperature melt impregnation process of N6.
Synthesis and Physical Properties of Hyperbranched Aromatic Polyamide
Ok Chang-Yul ; Kim Jang-Yup ; Huh Wansoo ; Lee Sang-Won ;
Polymer Korea, volume 29, issue 6, 2005, Pages 571~574
The aromatic hyperbranched polyamide was synthesized from 5-aminoisophthalic acid by direct polycondensation with triphenylphosphite (TPP) catalyst as a condensing agent. The modification of end-groups in the resulting hyperbranched polymer (HBP) with various alkyl alcohols were conducted. The modification of end-groups of HBP by alkyl groups resulted in an improved solubility in the THF comparing to that of the carboxylic acid-terminated aromatic HBP, Also, 10 wt
weight loss temperature decreased by increasing the length of alkyl group.
Synthesis and Characterization of Aliphatic Hyperbranched Polyesters
Kim Jang-Yup ; Ok Chang-Yul ; Lee Sang-Won ; Huh Wansoo ;
Polymer Korea, volume 29, issue 6, 2005, Pages 575~580
The hydroxy terminated aliphatic hyperbranched polyesters having different generations were synthesized by using melt polycondensation procedure. Then, the terminal groups of hyperbranched polyesters were modified by using acryloyl chloride and characterized by
-NMR and GPC techniques. As a result of the modification of terminal groups for hyperbranched polyesters, the phase of the polymers were changed from sticky solid to high viscous liquid indicating that the glass transition temperatures of modified hyperbranched polyesters were lower than the original one. The thermal stabilities of hydroxy terminated hyperbranched polyesters were higher than those of terminal group-modified polymers.
Surface Modification of Polyurethane Film Using Atmospheric Pressure Plasma
Yang In-Young ; Myung Sung-Woon ; Choi Ho-Suk ; Kim In-Ho ;
Polymer Korea, volume 29, issue 6, 2005, Pages 581~587
Commercial polyurethane film (PU) was modified with Ar plasma ionized in dielectric barrier discharge (DBD) plate-type reactor under atmospheric pressure. We measured the change of the contact angle and the surface fee energy with respect to the plasma treatment conditions such as treatment time, RF-power, and Ar gas flow rate. We also optimized the plasma treatment conditions to maximize the surface peroxide concentration. At the plasma treatment time of 70 sec, the power of 120 W and the Ar gas flow rate of 5 liter per minute (LPM), the best wettability and the highest surface fee energy were obtained. The 1,1 diphenyl-2-picrylhydrazyl (DPPH) method confirmed that the surface peroxide concentration was about 2.1 nmol/
at 80 W, 30 sec, 6 LPM.
Characteristics of Polycarbonate Film by Ion Beam for UV Block
Choi, Byoung-Hoon ; Kim, Young-Jun ;
Polymer Korea, volume 29, issue 6, 2005, Pages 588~592
For the purpose of obtaining polycarbonate film which blocks ultra-violet ion beam was irradiated onto the surface of PC film. This method has gotten several advantages compared with the techniques, such as the protection of changes in film thickness and UV blocking material deposited onto a base film. In order to investigate UV blocking PC film, the optical and chemical characteristics, surface morphology and lightfastness were confirmed by UV/Vis, FTIR(ATR) spectroscopy, AFM, and Q-UV fasoess analyses. As a result, it was shown that the modified PC film was able to block almost all of UV region and easily control the degree of UV block. The optical changes in the film were attributed to chemical changes in PC surface by ion beam irradiation. Moreover, we expect that the modified PC film can durably block UV due to no changes in colour and UV transmittance after UV fastness test.
pH-Dependent Dye Adsorption and Release Behaviors of Poly(ethylene-alt-maleic anhydride)/poly(4-vinyl pyridine) Multiplayer Films
Hong, Sook-Young ; Lee, Joon-Youl ;
Polymer Korea, volume 29, issue 6, 2005, Pages 593~598
This work studied the loading capabilities and release behaviors of poly(ethylene-alt-maleic anhydride) (PEMAh)/poly(4-vinyl pyridine) (P4VP) multilayer films formed by the layer-by-layer(LbL) sequential self-assembly method, using Rodamine 6G(R6G) as an indicator. Thickness of the multilayer, and loading and subsequent release behavior of R6G from the multilayer were studied using UV-visible spectroscopy. The amount of R6G loaded in multilayer film increased linearly with increasing film thickness. pH-Sensitive permeability was observed, where lower pH environments increased both release rate and release amount. By additional assembling of PEMAh/poly(ethyleneimine) (PEI) capping layers on top of (PEMAh/P4VP)n multilayers, the release of R6G was better controlled.
Characterization of Hyaluronic Acid Membrane Cross-linked with Lactide
Kwon, Ji-Young ; Cheong, Seong-Ihl ;
Polymer Korea, volume 29, issue 6, 2005, Pages 599~604
The hyaluronic acid (HA) with excellent biocompatibility has been combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials which can control the period of degradation in a human body. By freeze frying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance spectroscopy. Both lactyl group and EDC conversion increased as the mole ratio of lactide to HA increased from 5 to 13. The membrane swelled less and became more brittle with the more addition of lactyl group resulting from the higher mole ratio of lactide to HA. Swelling ratio decreased and tensile modulus increased due to the more addition of lactyl group as the EDC concentration increased or reaction temperature decreased. Drug release experiment from various membranes with different degree of crosslinking showed that permeability decreased with increasing degree of crosslinking. The degradation became slower with the more addition of lactyl group. Mechanical property and degradation rate of the synthesized membrane were shown to be controlled through adjusting operation parameters such as mole ratio, temperature, and crosslinking agent concentration.
A Study on the Characteristics of the Adiabatically Expanded Polyolefin Structured Foams
Hwang Jun-Ho ; Kim Woo-nyon ; Jun Jae-Ho ; Kwak Soon-Jong ; Hwang Seung-Sang ; Hong Soon-Man ;
Polymer Korea, volume 29, issue 6, 2005, Pages 605~612
This study investigates the isothermal crystallization behaviors of polypropylene-polyethylene-(1-butene) terpolymer and the adiabatically expanded polyolefin structured foams. For this purpose, butane gas was used as a physical blowing agent. Avrami equation has been used to interpret theoretically the experimental results obtained by either DSC or polarized optical microscope. It is believed that elongation induced crystallization occurring during the adiabatic expansion process has resulted in an increase in crystallization rate, eventually leading to a faster growth rate of spherulites and an increase in the nucleation density. An analysis of the foam by SEM images showed that the structure of foam is uniform (below diameter 30
m closed cell) In addition, the thermal conductivity and the compressive strength of the polyolefin structured foams was measured. The thermal conductivity of foamed resin with excellent insulation characteristics is reduced compared with unfoamed resin. The compressive strength is decreased with increase in the expansion ratio.
Synthesis of Enzyme-Containing PEG Hydrogel Nanospheres for Optical Biosensors
Kim, Bum-Sang ;
Polymer Korea, volume 29, issue 6, 2005, Pages 613~616
In this word as the first step to develop optical biosensors for a single cell level analysis, the preparation method of nano-scale polymer hydrogel spheres containing an enzyme was set up and the feasibility of the spheres as optical biosensors was investigated. The horseradish peroxidase (HRP) was encapsulated in the PEG hydrogel spheres by suspension photopolymerization, yielding spheres of the average size of 305 nm. After the polymerization, the incorporation and activity of HRP within the spheres were determined by the production of fluorescence resulted from the enzymatic reaction between HRP and
. The fluorescence emission response of the HRP-loaded PEG hydrogel spheres increased by nearly 300
as hydrogen peroxide concentration was changed from 0 to 11 nM in the presence of Amplex Red. The results suggest that the method to prepare the PEG hydrogel nanospheres containing an enzyme could be used for developing optical biosensors to measure various analytes in the very small samples like a single cell.