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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 27, Issue 6 - Nov 2003
Volume 27, Issue 5 - Sep 2003
Volume 27, Issue 4 - Jul 2003
Volume 27, Issue 3 - May 2003
Volume 27, Issue 2 - Mar 2003
Volume 27, Issue 1 - Jan 2003
Selecting the target year
Preparation of Polysiloxane Composite Films with Microphase-Separated Silicone Oiol by Photocrosslinking
Polymer Korea, volume 27, issue 1, 2003, Pages 3~8
Polysiloxanes with methacrylate groups at both terminals were synthesized by a hydrosilylation reaction between allyl methacrylate and hydride-terminated polysiloxanes. The polysiloxane methacrylates with high molecular weights could be prepared through the reaction of polysiloxane methacrylates and octamethylcyclotetrasiloxane with an acid catalyst. The structures of the prepared polysiloxane methacrylates were verified by
The polysiloxane methacrylates were freely miscible with silicone oils. Polysiloxane films with microphase-separated liquid silicone oil were prepared by photo-crosslinking the mixture of polysiloxane methacrylates and silicone oil. Scanning electron microscopy (SEM) of the films showed that the size of silicone oil droplets became smaller with a lower loading of silicone oil, lower molecular weight of polysiloxane methacrylate, and lower molecular weight of silicone oil.
Preparation and Characteristics of Ipriflavone-Loaded PLGA Microspheres
Polymer Korea, volume 27, issue 1, 2003, Pages 9~16
Ipriflavone (IP) stimulates proliferation and differentiation of osteoblast and also enhances calcitonin secretion in the presence of estrogen. Poly(lactide-co-glycolide) (PLCA) due to its controllable biodegradability and relatively good biocompatibility is one of the most significant candidates for the study of drug controlled release system. In this study, IP-loaded PLGA microspheres (MSs) was prepared by using conventional O/W solvent evaporation method. The size of MSs was in the range of 5~200
. The morphology of MSs was characterized by SEM. And, in vitro release amounts of IP were analyzed by HPLC. The highest encapsulation efficiency were obtained by using gelatin and polyvinyl alcohol (PVA) as emulsifiers. The morphology, size distribution, and in vitro release pattern of MSs were changed by several preparation parameters such as molecular weights (8, 20, 33 and 90 kg/mol), polymer concentrations (2.5, 5, 10 and 20%), emulsifier types (PVA, gelatin and Tween 80), initial drug loading amount (5, 10, 20 and 30%) and stirring speed (250, 500 and 1000 rpm). The release of IP in vitro was more prolonged over 30 days, with close to zero-order pattern by controlling the preparation parameters. The physicochemical properties of IP-loaded PLGA MSs were investigated by XRD and DSC.
Synthesis and Characterization of Polystyrene-b-Poly(acrylic acid) Block Ionomer via Atom Transfer Radical Polymerization
Polymer Korea, volume 27, issue 1, 2003, Pages 17~25
Using atom transfer radical polymerization (ATRP), polystyrene macroinitiators and polystyrene-b-poly(t-butyl acrylate) (PS-b-P(tBA) block copolymers were synthesized by CuBr/PMDETA catalyst system in solution. After hydrolysis, polystyrene-b-poly(acrylic acid), amphiphilic block copolymers, were formed. Subsequent neutralization of polyacid block led to the block ionomers. The molecular weight of the synthesized PS-b-P(tBA) block copolymers was easily-controlled to 5000-10000 and their distributions were less than 1.2. The chemical structures of the synthesized block copolymers were characterized by
H-NMR and FT-IR. In the DSC thermograms,
appeared in the vicinity of 100
because of higher styrene content. In addition, the phase separation of the block ionomers was observed by TEM.
Synthesis of Poly(vinyl pivalate) Telomer Through Telomerization of Vinyl Pivalate
Polymer Korea, volume 27, issue 1, 2003, Pages 26~32
Poly(vinyl pivalate)(PVPi) telomer containing bifunctional end groups was synthesized through radical telomerization of vinyl pivalate. The number-average molecular weight (
n) of the synthesized telomers was investigated by GPC,
H-NMR, and viscometric methods. PVPi telomers having a number-average molecular weight (
n) of 2400~1300 g/mol were obtained. In order to control the molecular weight of telomers, chain transfer constants (
) of telogen (
) were determined by using the Mayo equation and simulation, which were 1.15, 1.16, and 1.18 at 40, 50, and 6
n of the synthesized telomers at 6
were between 5100 and 5400 g/mol at conversion of increasing from 18 to 72%. Those are corresponding to simulation results.
Thermal Properties and Fracture Toughness of Bisphenol-Based DGEBA/DGEBS Epoxy Blend System
Polymer Korea, volume 27, issue 1, 2003, Pages 33~39
In this study, the bisphenol-based DGEBA/GEBS blend systems were studied in cure kinetics, thermal stabilities, and fracture toughness of the casting specimen. The content of DGEBA/DCEBS was varied in 100 : 0, 90 : 10, 80 : 20, 70 : 30, and 60 : 40 wt%. The cure activation energies (
) of the blend systems were determined by Ozawa's equation. The thermal stabilities, including initial decomposed temperature (IDT), temperatures of maximum rate of degradation (
), and integral procedural decomposition temperature (IPDT) of the cured specimen were investigated by thermogravimetric analysis (TGA). For the mechanical interfacial properties of the specimens, the critical stress intensity factor (
) test was performed and their fractured surfaces were examined by using a scanning electron microscope (SEM). As a result,
, IPDT, and
show maximum values in the 20 wt% DGEBS content compared with the neat DGEBA resins. This was probably due to the fact that the elevated networks were farmed by the introduction of sulfonyl groups of the DCEBS resin.
Electrical and Physical Properties of Magnetite-Filled NBR
Polymer Korea, volume 27, issue 1, 2003, Pages 40~45
In this work, the effect of different contents of
and temperature variation on the electrical conductivity (
) in the polar acrylonitrile butadiene rubber (NBR)/
(magnetite) mixture system was investigated. It was found that the percolation threshold concept holds true for the conductive particle-filled composites where
indicates a nearly sharp increase when the concentration of magnetite in the mixture exceeds 22%. The temperature dependence of
was thermally activated below and at the percolation threshold (
). Magnetite acted as reinforcing and conductive filler for NBR. At room temperature and higher voltages, the electrical current was proportional to the square of voltage (
) for the composites which contain 30 phr of magnetite. Moreover, it was shown that the composites with magnetite of 50 phr showed the highest tensile strength and elongation at break, which was due to the formation of optimal physical interlock and crosslinking. The results of 100%, 200%, and 300% Young moduli said that the moduli are largely correlated with reinforcement effect of magnetite and viscosity of the blends from torque curve.
Adsorption Properties of Fuel-Cell Electrode Produced from Activated Carbon Fibers in Three Phase Distribution
Polymer Korea, volume 27, issue 1, 2003, Pages 46~51
In this work, the electrode far fuel cell was fabricated by mixing carbon blacks with activated carbon fibers (ACFs) in order to form the proper three phase distribution, and then the change of electrode in three phase distribution was investigated. Pt loading yield with ACF content and Pt particle size were determined by AAS and XRD measurements, respectively. And the pore structures, including specific surface area (
), microporosity, and pore size distribution (PSD) for each electrode were systematically investigated by BET volumetric measurement. The morphology of electrode in three phase distribution was determined by SEM. As an experimental result, it was observed that Pt loading yield was not influenced on the content of ACF. While, the electrode in three phase distribution was largely improved in the case of 30% ACF addition on carbon blacks. These results were probably explained by the increase of the portion of micropores, resulting in increasing the active sites of catalyst.
Impact Behaviors of Ni-plated Carbon Fibers-reinforced Epoxy Matrix Composites
Polymer Korea, volume 27, issue 1, 2003, Pages 52~60
In this work, two types of Ni-plating, namely electrolytical and electroless Ni-platings on carbon fiber surfaces, were carried out to enhance the impact resistance of composites. And the comparison between electrolytical and electroless methods on their impact properties of composite system was studied. The surface properties of carbon fibers were characterized using XRD, SEM, and contact angle measurements. The impact behaviors were investigated using an Izod type impact tester. As experimental results, it was observed that electrolessly plated Ni layers had Ni-P alloys on carbon fiber surfaces as revealed by XRD, and electrolytically Ni-plated carbon fibers showed higher surface free energies than those of the electrolessly Ni-plated carbon fibers. In particular, the impact strengths of electrolessly Ni-plated carbon fibers-reinforced plastics were strongly increased. These results were probably due to the difference of wettabilities according to the different types of Ni-plating methods.
Adsorption Properties of Nickel ion from Plating Rinse Water Using Hybrid Sulfonated Bead and Fibrous Ion Exchanger
Polymer Korea, volume 27, issue 1, 2003, Pages 61~68
In this study, we have investigated the preparation of mixed bead and fiber type hybrid ion-exchanger for recovering nickel ion from plating rinse water. There was little dependence of adsorption capacity for nickel ion on the mixing ratio of resin type and fiber type of ion exchangers. However, it increased with increasing the resin content in the mixed bed. It was shown that the data Langmuir and Freundlich's adsorption isotherm model were well fitted to the linear. Affinity between the functional groups in the ion exchanger and nickel ion in the process was confirmed. The pressure drop decreased with increasing the number of stage in the multistage bed, but it increased with increasing the resin content in the mixing bed. The initial breakthrough time in the multistage bed was short due to the increase of number of stage in the continuous process. It was found that the final breakthrough time of the multistage bed was little changed. The breakthrough time decreased with increasing the amount of fibrous ion exchanger in the mixed bed. The maximum adsorption capacities of the mixed and multistage beds were 2.51 meq/g and 2.69 meq/g, respectively. The desorption time for the nickel ion with
solution was lower than 10 minutes and the yield of desorption was greater than 98 percent.
Selective Adsorption Properties of Nitrate ion in Sulfate and Nitrate Solution by Bead and Fibrous Hybrid Ion Exchange Bed
Polymer Korea, volume 27, issue 1, 2003, Pages 69~74
In this study, we have investigated the adsorption properties for nitrate ion in ground water using mixed resin type hybrid ion exchange (HIXF) and fiber type ion exchanger. Their swelling ratio (4.45 g/g) and ion exchange capacities (2.45 meq/g) were higer than the swelling ratio of IEC and IXF. Adsorption yield increased for nitrate
ions were optimal at the concentration ratios of nitrate and sulfate below 1.0 and the adsorption yields were 100% and 20%, respectively. On the other hand it was shown that the degree of adsorpted for nitrate to pH 3, but it was little changed in the other pH range. We found that the selective adsorption capacity for nitrate was the optimal the mixing ratios of resin and fibrous ion exchanger of below 0.5.
Reactive Dispersion and Mechanical Property of Dicyanate/Montmorillonite Nanocomposite
Polymer Korea, volume 27, issue 1, 2003, Pages 75~83
Dicyanate-clay nanocomposite has been prepared by a melt in-situ polymerization method for different modifiers and cation exchange capacity (CEC) values in order to study dispersion and mechanical property. Various dicyanate nanocomposites were prepared by using different MMT systems containing different intercalants which led to different initial gallery heights and packing density. Depending on compatibility between dicyanate and clays, the degree of dispersion varied. Dispersion of clay plates in dicyanate resin depended mainly on CEC and aliphatic chain length of modifier. The lower CEC and shorter aliphatic chain length of modifier gave the exfoliation structure. It was also found that the reactivity of intercalant with dicyanate resin was one of the key factors facilitating the intercalation/exfoliation process of dicyanate/MMT nanocomposites. Shear modulus of reaction-induced dicyanate nanocomposite was significantly increased.
Liquefaction Characteristics of HDPE by Pyrolysis
Polymer Korea, volume 27, issue 1, 2003, Pages 84~89
Pyrolysis of high density polyethylene(HDPE) was carried out to find the effects of temperature and time on the pyrolysis. The starting temperature and activation energy of HDPE pyrolysis increased with increasing heating rate. In general, conversion and liquid yield continuously increased with pyrolysis temperature and pyrolysis time. This tendency is very sensitive with pyrolysis time, especially at 45
. Pyrolysis temperature has more influence on the conversion than pyrolysis time. Each liquid product formed during pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. As a result, the amount of liquid products produced during HDPE pyrolysis at 45
was in the order of light oil > wax > kerosene > gasoline, and at 475
, it was wax > light > oil > kerosene > gasoline.