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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal Basic Information
Journal DOI :
The Polymer Society of Korea
Editor in Chief :
Volume & Issues
Volume 24, Issue 6 - Nov 2000
Volume 24, Issue 5 - Sep 2000
Volume 24, Issue 4 - Jul 2000
Volume 24, Issue 3 - May 2000
Volume 24, Issue 2 - Mar 2000
Volume 24, Issue 1 - Jan 2000
Selecting the target year
The Comparison between Ziegler-Natta and Zirconocene Catalyst on Reaction Conditions and Physical Properties in Polymer in Propylene Polymerization
Polymer Korea, volume 24, issue 4, 2000, Pages 437~444
Propylene polymerizations were carried out by using rac-Et(Ind)
(Zirconocene catalyst) and a commercial third generation Ziegler-Natta catalyst in a semibatch reactor. From the polymerization reactions, the optimum reaction conditions and the physical properties of polymers produced from each catalyst system were investigated. The optimum reaction temperatures of rac-Et(Ind)
and Ziegler-Natta catalyst were 5
, respectively. On the basis of the results for the produced polymer particle size distributions and the catalytic activities of polymerization reaction, the reaction temperature should be considered as an important factor for the successful polymerization reactions. Especially, the polymer was conglomerated in the higher reaction temperature. It was found that there was an upper limitation to co-catalyst concentration. Reaction rates and polymer yields rather decreased with increasing the concentration of to-catalyst, i.e., MAO and TEAl affected only polymerization activities, but the PEEB in Ziegler-Natta catalyst system affected isotactic indexes of produced polymer as well as activities. Based on these observations, the production yield seems to exhibit a first order lineal relationship to the partial pressure of monomer.
Copolymerization of Ethylene and Cycloolefin with Metallocene Catalyst: I. Effect of Catalyst
Polymer Korea, volume 24, issue 4, 2000, Pages 445~452
The copolymerization of ethylene (E) and norbornene (N) was examined by using various metallocene catalysts and modified-MAO(MMAO) cocatalyst. For
-symmetry catalysts such as rac-Et(Ind)
and Cs-symmetrical iPr(FluCp)ZrC
as well as CGC and di-bridged zirconocene, the effects of catalyst structure and [N]/[E] feed ratio on catalyst activity, thermal property and [N] content of copolymer (COC) was investigated. For rac-Et(Ind)
catalyst of a constant [N]/[E] feed ratio, the appropriate conditions of [Al]/[Zr] mole ratio, polymerization temperature and cocatalyst structure were found to be 3000, 4
, MMAO cocatalyst, respectively. As [N]/[E] feed ratio increased, the incorporation of norbornene to copolymer increased while, the activity of catalyst decreased except for iPr(FluCp)ZrC
With consideration of catalyst activity as well as N content, it was found that rac-Et(Ind)
/MMAO system exhibited relatively high activity and controllable
. Monomer reactivity ratio was determined by Kelen-Tudos method..
Gas Permeability of Polymeric LB Films Containing Imidazole-Metal Ion Complexes
Polymer Korea, volume 24, issue 4, 2000, Pages 453~458
The permeability of oxygen and nitrogen was investigated from the polymeric LB films containing imidazole-metal ion complexes and compared with its corresponding cast films on porous membrane filters. The amphiphilic polymer, poly(N- (2-(4-imidazolyl)ethyl)-maleimide-alt-1-octadecene) (IM-O), was synthesized by reaction of poly(maleic anhydride-alt-1-octadecene) with histamine. The IM-O nonolayer showed high stability on Fe (III) ion-containing subphase. The molecular structure in the LB films was investigated by means of FT-IR spectroscopy. The metal ion concentration incorporated into the LB films was determined by means of XPS measurements. The mechanical stability and uniformity of the LB films on porous substrates were indirectly evidenced by SEM observation. The LB and cast films showed more or less higher selectivity toward nitrogen, and high permeability was found to both the oxygen and nitrogen.
Matrix Resin Systems with Different Molar Ratios to Improve the Properties of Fiber-reinforced Composites
Polymer Korea, volume 24, issue 4, 2000, Pages 459~468
To improve the mechanical properties of fiber-reinforced polymer matrix composites, laminated composites plates were fabricated using different matrix resins and glass or aramid fibers. The effect of matrix resin system were evaluated by tensile, flexural strength measurements. In the case of surface treated aramid fiber and unsaturated polyester resin composite, maximum flexural properties were observed in the composite prepared from the glass fiber treated with 0.5 wt% silane coupling agents. Vinylester resin composites show the highest tensile properties and isophthalic polyester composites have the highest flexural properties among the unsaturated polyester resin composites studied. The relationship between overlap laminated composites plates and mechanical properties of polymer composites is also investigated in order to improve mechanical properties of glass fiber and unsaturated polyester resin composites.
The PSA Properties of n-Butyl Acrylate/Acrylic Acid Copolymer and Tackifier Resins with Influence of Miscibility
Polymer Korea, volume 24, issue 4, 2000, Pages 469~476
The miscibility between acrylic copolymers and tackifier resins influenced on adhesion properties of PSA. PSA with high molecular weight and narrow molecular weight distribution of acrylic copolymers showed systemical modification of adhesion properties of PSA by tackifier resins only in case of miscible system. It is concluded that the investigation of the miscibility between two Components is very important to adhesion properties of PSA.
Thermal Properties and Crystallization of Biodegradable Poly(L-lactic acid) and Poly(
Polymer Korea, volume 24, issue 4, 2000, Pages 477~487
A series of poly(L-lactic acid) (PLLA)/poly(
-hydroxynonanoate) (PHN) blend were prepared to study the miscibility and the crystallization behaviors. The thermal behaviors and characterization of PLLA/PHN blends Were studied using differential scanning calorimetry (DSC), XRD and polarizing optical microscopy (POM). The PLLA and PHN are partially miscible in amorphous region. The crystallinity of PLLA increased as the content of PHN increased, and T
, and T
of PLLA shift as the content of PHN increased. Moreover, the number of PLLA spherulite increased as the content of PHN increased in the POM experiment. Thus, PHN acted as a nucleating agent to PLLA.
Effects of Molecular Weight of Poly(4-vinylpyridine) on the Order-Disorder Transition of Molecular Bottle-brush Composed of Poly(4-vinylpyridine) and 3-Pentadecylphenol
Polymer Korea, volume 24, issue 4, 2000, Pages 488~498
Molecular bottle-brush was prepared by hydrogen-bonding between poly(4-vinylpyridine)(P4VP) as main chain and 3-pentadecylphenol (PDP) as amphiphilic side chain. Variation of long period (
), order-disorder transition temperature (
) and mesomorphic structure of bottle-brush were investigated by changing various mole ratio (x) of pyridine group in P4VP and PDP and molecular weight of P4VP. Upper critical solution temperature (UCST) behaviour was observed. For x 0.8-0.9, maximum critical temperature was found. As molecular weight of P4VP was increased, phase transition occurred at higher temperature. It was found that phase behaviour of the bottle-brush was affected by mobility of P4VP as well as size and regularity of lamellar structure. The
determined from analysis of crystal structure was in the range of 35
and was more affected by the molecular weight of P4VP than by mole ratio (x). However, if the molecular weight of P4VP was high, LP value was little affected.ted.d.
Effect of Anodized Carbon Fiber Surfaces on Interfacial Adhesion of Carbon Fiber-reinforced Composites
Polymer Korea, volume 24, issue 4, 2000, Pages 499~504
The effect of anodic oxidation on high strength PAN-based carbon fibers has been studied in terms of surface functionality and surface energetics of the fiber surfaces, resulting in improving the mechanical properties of composites. According to FT-IR and XPS measurements, it reveals that the oxygen functional groups on fiber surfaces induced by an anodic oxidation largely influence the surface energetics of fibers or the mechanical interfacial properties of composites, such as the interlaminar shear strength (ILSS) of composites. According to the contact angle measurements based on the wicking rate of a test liquid, it is observed that anodic oxidation does lead to an increase in surface free energy of the carbon fibers, mainly due to the increase of its specific (or polar) component. From the surface energetic point of view, it is found that good wetting plays an important role in improving the degree of adhesion at interfaces between fiber and epoxy resin matrix of the resulting composites. Also, a direct linear relationship is shown between 01s/01s ratio and ILSS or between specific component and ILSS of the composites for this system.
Mixture Density Measurement of Biodegradable Poly(lactide-co-glycolide) Copolymer in Supercritical Solvents
Polymer Korea, volume 24, issue 4, 2000, Pages 505~512
The mixture density data for poly(lactide-co-glycolide) [PLGA] with supercritical
were obtained in the temperature range of 27 to 10
and at pressures as high as 3000 bar (PLGA
, Where the molar concentration of glycolide in the backbone, x, range from 0 to 50 mol%). The PLA-
, and PLA-CHClF
systems dissolve in the pressure less than 1430 below 700, and below 100 bar, respectively. The mixture density shows from 1.084 to 1.334 g/cm
at temperatures from 27 to 93
. The PLGA
mixture dissolves at pressures of below 1900 bar and the mixture density is in the range of 1.158 to 1.247 g/cm
at temperatures between 37 and 92
. The solubilities of the PLGA
, and CHClF
are shown to pressure as high as 2390, 1470, and 118 bar, respectively, and the mixture density exhibits iron 1.154 to 1.535 g/cm
at temperatures from 29 to 81
. The PLGA
system does not dissolve at 24
and 3000 bar while the PLGA
does easily at 5
and 100 bar. The mixture density for the PLGA-CHClF
system increases even at low pressures as the glycolide molar concentration increases.es.es.
Study on the Thermal Properties and Adhesion Strength of Amorphous Polyalphaolefins/Petroleum Resin Blonds as a Hot Melt Adhesive
Polymer Korea, volume 24, issue 4, 2000, Pages 513~519
The effect of petroleum resin as a tackifier for polyalphaolefin (APAO) hot melt adhesive on thermal properties, crystallinity and adhesion strength was investigated. The presence of petroleum resin resulted in the melting temperature decrease in APAO/petroleum blend, especially, in APAO with low ethylene content/C
petroleum blend. It was also found that petroleum resin caused the decrease of crystallinity regardless of ethylene content in APAO. The maximum adhesion strength was found to be at 50/50 (APAO/petroleum) composition.
resin was more effective to increase adhesion strength than
for APAO with high ethylene content. In addition, it was found that the adhesion strength was improved with the decrease of crystallinity in APAO/petroleum resin hot melts.
The Preparation and Characteristics of High Solids Acrylic/Polyisocyanate Coatings
Polymer Korea, volume 24, issue 4, 2000, Pages 520~528
New high solid acrylic resins (BMHA) containing 70% of solids content have been synthesized. The environmental friendly high solid coatings (BNHS) were prepared by using these acrylic resins and polyisocyanates. The BMHA was obtained by introducing a new functional group, acetoacetoxyethyl methacrylate (AAEM), in the copolymerization of n-butyl acrylate, methyl methacrylate, and 2-hydroxyethyl acrylate. Lowering T
and increasing the AAEM amount in the BMHA resulted in a high value of conversion. There was no difference in conversion with the variations of OH values. In the next step, high solid BNHS coatings were prepared by the curing reaction between BMHA and polyisocyanate at room temperature. The properties of these coatings were evaluated especially for the application of automotive top-coating materials. The introduction of AAEM in the BNHS enhanced the abrasion resistance and solvent resistance of the coatings, which indicated the possible use of BNHS coatings for top-coating materials of automobile..
Structural Development of Polypropylene Foam by Crosslinking and Processing Conditions
Polymer Korea, volume 24, issue 4, 2000, Pages 529~537
The effects of the gel content on the cell structures of PP sheets by using an electron-curing system were investigated. Three extruded PP sheets crosslinked by three different doses were used for the batch foaming process with the supercritical state
. Experiments were also performed in order to study the effects of the gel content, saturation pressure and temperature on cell structures. Then foaming conditions, such as temperature and duration of time, were changed. The amount of gas absorbed into PP samples was not affected by gel contents and the operating condition of saturation pressure, which was higher than 2000 psi. The foam cells of PP with a low gel content grew irregularly at a higher foaming temperature and for a longer duration of foaming time. However, PP samples with high gel content showed even cell structures and narrow tell size distributions under the severe conditions of high foaming temperatures and long duration of foaming time.
A Study on the Extrusion Foaming of Polypropylene
Polymer Korea, volume 24, issue 4, 2000, Pages 538~544
The characteristics of cell growth and foamed cell structures of PP were investigated by a continuous foaming process. The operating parameters were the contents of blowing agent and nucleating agent, nucleating agent contents, die temperatures and die dimensions. The foaming cells grew without collapse at less than 14.5 wt% of blowing agent, isopentane. But the cells were collapsed when the blowing agent content was more than 14.5 wt%. The foam density dramatically decreased when a very small amount of the nucleating agent, 1 wt%, was added. After the nucleating agent was added, the cell's weight plummeted to one-seventh of its previous weight. Stable foam cell structures were formed at the die temperature of 17
. However, the effects of the pressure drop rate on the cell morphology were not serious.
Analysis of Mold Filling Associated with Unsteady Flow in Injection Molding Process
Polymer Korea, volume 24, issue 4, 2000, Pages 545~555
Surface defects in injection molded parts due to the unsteady flow are related to the dimension of gate, operational conditions and rheological properties of polymer. In this study we have examined surface defects in injection molding for PC, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes that are tensile, flexural and impact test specimens with various gate and cavity thicknesses. Through this study we have observed that the formation of surface defect associated with jetting during filling stage in injection molding is strongly related to not on]v die swell but retardation of die swell. Large die swell eliminates jetting however the large retardation of die swell stimulates jetting. Reducing the thickness ratio of cavity to gate can reduce or eliminate jetting and surface defects. It also enlarges process window that can produce steady flow of polymer melt in injection molding.
Fabrication of PP/Carbon Fiber Composites by Introducing Reactive Interphase and its Properties
Polymer Korea, volume 24, issue 4, 2000, Pages 556~563
In general, the development of thermoplastic composites has been confronted with difficult problems such as the weak bonding strength between fibers and matrix. However, now, such problems are being surmounted by the development of resins, the improvement of processes, and introduction of interphase. Especially, the introduction of interphase between fiber and matrix can help a dissipation of the impact energy and provide a good adhesion between fibers and matrix. In this study, polymeric interphase was introduced by electrodeposition, modified polypropylene was added to improve the weak bonding strength between interphase and polypropylene matrix. By evaluation of interlaminar shear strength and impact strength of the composites, it was found that composites with introduced composites showed higher mechanical properties than those of composites without interphase. Reactive polymers which have either anhydride or free acid functional group were used as interphase materials, and these polymers also behave as charge carrier in aqueous solution during the electrodeposition process. Weight gain on the carbon fibers was evaluated by changing process parameters such as concentration of solution, current density, and electrodeposition time.
A Study on the Preparation and Mechanical Properties of Hybrid Composites Reinforced Waste FRP and Urethane Foam
Polymer Korea, volume 24, issue 4, 2000, Pages 564~570
The waste FRP occured in the fabrication of SMC (sheet molding compound) bathtubs and the waste polyurethane foam occured in electronic manufacture and waste insulator were applied as a soundproof and light weight pannel in the waste FRP unsaturated polyester matrix resin composites to recycle. The effect of filler contents on the mechanical properties and interfacial phenomena of the filler and matrix on the composites was evaluated. The tensile strength of composites reached its maximum value of 82.34 MPa when the filler content was 70 wt%, and the more content of reinforcement is increased, the more tensile modulus was decreased. The flexural strength and modulus of composites, reinforced 70 wt% with filler content, were dominant compared to the other samples to 72.5 MPa, 958.4 MPa respectively. When composite of reinforced 70 wt% with filler content, it was confirmed that pull out phenomena and cracks did not occur in the interface of reinforcement and matrix resin through the SEM observation. Also, waste FRP and urethane foam were dispersed well into matrix resin as filler.
Nanocomposites from Epoxy Resin and Layered Minerals
Polymer Korea, volume 24, issue 4, 2000, Pages 571~577
A new type of filler for epoxy-clay nanocomposites has been prepared by the reaction of octadecyltrimethylammonium bromide and layered sodium montmorillonite (MMT) via an ion-exchange reaction. The gallery space was further modified by grafting the aminopropyl groups via a reaction between a octadecyltrimethylammonium-MMT and 3-aminopropyltriethoxysilane (APS). The interlayer modification of MMT was confirmed by XRD, IR, and solid-state
Si CP/MAS NMR. Furthermore, clay-polymer nanocomposites have been synthesized by the polymerization of diglycidyl ether of bisphenol A(DGEBA) and
-APS-MMT. The resulting hybrid nanocomposites were characterized by XRD, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results proved that the organomontmorillonite could be exfoliated and uniformly dispersed in the epoxy matrix.