• 한국기계가공학회지
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• 제14권5호
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• pp.126-133
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• 2015

Recently, there has been demand for polymeric porous membranes in various fields, such as environmental engineering, pharmaceutics, tissue engineering, drug delivery, biology, and fuel cells. In this study, it is proposed that a polymer particle-based porous membrane can be fabricated using electrospraying and sintering processes. Electrospraying can fabricate polymeric particles with diameters ranging from several micrometers to tens of nanometers without the cumbersome particle aggregation problem. Additionally, the particles can be sintered through thermo-compression under the glass transition temperature. In this study, a polymethyl methacrylate particle-based porous membrane with an average pore size of less than 500 nm is fabricated using the proposed method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.793-796
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• 2003

This study dealt with the manufacturing process of self-healing microcapsules for damage repair in polymeric composites. The microcapsule was consisted with a DCPD (dicyclopentadiene) as the healing agent and a urea-formaldehyde resin as the wall section. The size distribution of microcapsules were measured by a particle size analyzer using a laser diffraction technique. Thermal stability of microcapsules was investigated by using a TGA under continuous and isothermal heating conditions. According to the results, these microcapsules were verified to be to thermally stable and have a great potential to be applicable for damage repair in polymeric composites.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2747-2752
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• 2013

Surface modification of colloidal silica nanoparticles without disrupting the electric double layer of nanoparticles is a major challenge. In the work, silane was employed to modify colloidal silica nanoparticles without inducing bridge flocculation obviously. The effect of pH value of the silica sol, the amount of silane in feed, and reaction temperature on the graft amount and the final size of modified particles was investigated. The increased weight loss by TG and the appearance of $T_2$ and $T_3$ except for $Q_2$ and $Q_3$ signals by CP/MAS $^{29}Si$ NMR of the modified samples verified the successful grafting of silane. The graft amount reached 0.57 mmol/g, which was slightly lower than theory value, and the particle size remained nearly the same as unmodified particles for acidic silica sol at the optimum condition. For alkaline silica sol after modification, aggregates composed of several nanoparticles connected together with silane moleculars as the bridge appeared.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.503-509
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• 2006

Molecularly imprinted polymeric microbeads (MIPMs) were prepared by the suspension and modified suspension polymerization methods using D-phenylalanine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, toluene as the porogen, polyvinyl alcohol as the stabilizer, and sodium dodecyl sulfate as the surfactant. The addition of a surfactant to the conventional suspension polymerization mixture decreased the mean particle size of the MIPMs and increased the adsorption selectivity. For the modified suspension polymerization method, the mean particle size of the MIPMs was smaller than the particle size of MIPMs prepared via conventional suspension polymerization. Moreover, the adsorption selectivity improved considerably compared to the adsorption selectivities of MIPs reported previously.

• Macromolecular Research
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• 제17권7호
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• pp.538-543
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• 2009

In this study, methotrexate (MTX)-encapsulated polymeric micelles using methoxy poly(ethylene glycol) (MPEG)-grafted chitosan (ChitoPEG) copolymer were prepared. The MIX-incorporated polymeric micelles of ChitoPEG copolymer has a particle size of around 50-100 nm. In 1H nuclear magnetic resonance (NMR) study, the specific peaks of MTX disappeared in heavy water ($D_2O$) and only the specific peak of MPEG was observed, while all of the peaks were confirmed in dimethyl sulfoxide (DMSO). These results indicated that MTX was complexed with chitosan and then formed an ion complex inner-core of the polymeric micelle in an aqueous environment. The drug contents of the polymeric micelle were around $4{\sim}12%$ and the loading efficiency of MTX in the polymeric micelles was higher than 60% (w/w) for all of the formulations. The cytotoxicity of MIX and MTX-incorporated polymeric micelle against CT26 tumor cells was not significantly changed.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.179-186
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• 1996

The magnetic fibrous polymeric oil filter for automotive was obtained by pneumoextrusion processing prepared from thermoplastic polymer(polyamide) containing magnetic particulate filer (Ba ferrite), and treated subsequently in a magnetic fields. Using an oil filter tester and particle quantifier, the dependence of filtrational characteristics of the magnetic oil filter on the parameters of mean pore sizes and magnetic properties were analyzed. Also experimental engine-bed test of oil filters was investigated. The magnetic fibrous polymeric filter was shown to possess a highly filtration efficiency in filtering the fine metal particles with increasing the magnetic force of filter element. In this study, we knew that efficiency of magnetic fibrous polymeric filter was dependent on the magnetic strength of the filter elements.

• Tribology and Lubricants
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• 제11권2호
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• pp.8-14
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• 1995

The filtration of the magnetic fibrous polymeric filter with packing density profile made of a self-bonded, nonwoven structure comprising a thermoplastic polymer and a magnetic substance was investigated using an oil filter tester, a particle quantifier and an image analyzer system. The magnetic fibrous polymeric filter showed excellent filtration efficiency compared with conventional paper filter. From the experimental results, It is deduced that the filtration mechanism of conventional paper filter is only the function of physical porosity by surface filteration. On the other hand, the newly magnetic fibrous polymeric filter is designed with a new concept in filtration mechanism. That is, it has a dual function of depth and magnetic filters by physical porosity and magnetic attraction. The newly magnetic fibrous polymeric filter has been shown to be a highly effective oil filter for lubrication systems.

• Tribology and Lubricants
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• 제12권3호
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• pp.39-47
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• 1996

The magnetic fibrous polymeric oil filter elements for industrial lub-systems were obtained by pneumoextrusion processing prepared from thermoplastic pqlymer (polyamide) containing a magnetic particulate filler (Ba ferrite), and treated subsequently in a magnetic fields. Using the standard laboratory oil filtration test rig, metallic particle quantifier and image analyser system, the dependence of filtration charateristics of the magnetic filter media on the parameters of porosity and magnetic properties was investigated. The pressure drops and efficiencies of lubricating filter elements were measured on the packing density and magnetised filler content of filter element. Also, the industrial lub-systems such as lubricant filters for gear test rig and electric discharge processing machine were used for testing the flitrational characteristics of tl, c magnetised filter elements. The magnetic fibrous polymeric filter material was shown to possess a highly filtration efficiency in filtering the fine ferrous particles with increasing the magnetic force of filter element. Therefore, it is expected that the magnetic fibrous polymeric filter material should be used for effective oil filrers on the industrial lub-systems.

• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.383-388
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• 2000

Multiblock copolymers consisting of poly( g-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) as the hydrophilic part (GEG) were synthesized and characterized. GEG polymeric micelles were prepared by the dialysis technique. Particle size distributions based on intensity,volume, and number-average were 22.6 $\pm$ 11.9 nm, 23.5 $\pm$ 4.6 nm, and 23.7 $\pm$ 37 nm, respectively. It was observed that par-ticle size and size distribution of GEG polymeric micelles changed significantly with the choice of initial sol-vent. Transmission electron micrographs (TEM) showed the polymeric micelles to be spherically shaped, with sizes ranging from 20 nm to 40 nm in diameter. Fluorescence spectroscopy measurements suggested that GEG block copolymers wereassociated in water to form polymeric micelles, and the critical micelle concentrations (CMC) value of the block copolymers was 0.0094 g/L. Further evidenceof micelle formation of GEG block copolymers and limited mobility of the PBLG chain in the core ohe micelle was obtained with 1 H NMR in D2O.

• Korea-Australia Rheology Journal
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• 제18권4호
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• pp.171-181
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• 2006

We present a short review for authors' previous work on direct numerical simulations for inertialess hard particle suspensions formulated either with a Newtonian fluid or with viscoelastic polymeric fluids to understand the microstructural evolution and the bulk material behavior. We employ two well-defined bi-periodic domain concepts such that a single cell problem with a small number of particles may represent a large number of repeated structures: one is the sliding bi-periodic frame for simple shear flow and the other is the extensional bi-periodic frame for planar elongational flow. For implicit treatment of hydrodynamic interaction between particle and fluid, we use the finite-element/fictitious-domain method similar to the distributed Lagrangian multiplier (DLM) method together with the rigid ring description. The bi-periodic boundary conditions can be effectively incorportated as constraint equations and implemented by Lagrangian multipliers. The bulk stress can be evaluated by simple boundary integrals of stresslets on the particle boundary in such formulations. Some 2-D example results are presented to show effects of the solid fraction and the particle configuration on the shear and elongational viscosity along with the micro-structural evolution for both particles and fluid. Effects of the fluid elasticity has been also presented.