• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.123-128
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• 2001

The Purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. This paper deals with the effect of the monomer ratio on the typical properties of polymer-modified mortars with methyl methacrylate-butyl acrylate latexes. The polymer latex-modified mortars are prepared with 5, 10, IS and 20% of polymer cement ratio respectively, and properties of modified mortars such as water absorption, compressive and flexural strengths, chloride-ion penetration depth are tested. The test results indicate that the monomer ratio is very important factors to characterize the strength properties of polymer-modified mortars, but the water absorption and chloride-ion penetration depth are influenced by polymer-cement ratio rather than monomer ratios.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.343-348
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• 2007

Molecular dynamics study of thermal NIL (Nano Imprint Lithography) process is performed to examine stamp-resist interactions. A layered structure consists of Ni stamp, poly-(methylmethacrylate) thin film resist and Si substrate was constructed for isothermal ensemble simulations. Imposing confined periodicity to the layered unit-cell, sequential movement of stamp followed by NVT simulation was implemented in accordance with the real NIL process. Both vdW and electrostatic potentials were considered in all non-bond interactions and resultant interaction energy between stamp and PMMA resist was monitored during stamping and releasing procedures. As a result, the stamp-resist interaction energy shows repulsive and adhesive characteristics in indentation and release respectively and irregular atomic concentration near the patterned layer were observed. Also, the spring back and rearrangement of PMMA molecules were analyzed in releasing process.

• Journal of the Korean Society of Clothing and Textiles
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• v.7 no.1
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• pp.11-16
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• 1983

Variance of whiteness after graft copolymerization of acrylonitrile, methylmethacrylate and acrylamide onto bleached cellulose using Ce(IV) salt as initiators and the effect of homopolymer on the grafted fibers by photo-irradiation were studied. Also, the development of Yellowing were determined after carbon-arc radiation in a Fade-o-meter. The results were as follows: (1) Variation of whiteness of grafted cellulose fibers were influenced by graft-ratio, Inorganic-Organic Balance (IOB) of functional group in used monomers and adhering homopolymers on the grafed fibers. (2) Yellowing was not affected by the concentration of Ceric Ammonium Nitrate directly during reaction (eg. 0.008>0.006>0.014 M).

• Journal of the Korean Graphic Arts Communication Society
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• v.13 no.2
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• pp.1-17
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• 1995

Organic thin film electroluminescene devices were fabricated using by molecularly doped method with N,N`-diphenyl-N,N`-bis(3-methylphenyl)-1,1`-biphenyl-4,4`-diamine(TPD) as a hole transport material, tris(8-quinolinolate) aluminium(III)(Alq3) as an emitting and electron transport agent, fluorescent squarylium(SQ) dye as a dopant, and poly(methylmethacrylate) as polymer materials. A cell structure of ITO/TPD-PMMA/Alq3-dopant/Mg was employed. The EL spectrum covers a wide range of the visible region and orange emission os observed. Two peaks at 520 and 660nm correspond to the emissions 620nm Alq3 and SQ dye, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.310-313
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• 2008

Recently, study on the weak interaction energy between the soft polymer surface and liquid crystals has been a primary topic for new LC device applications. In this paper, to understand the switching property of nematic liquid crystals (LCs) at the interface with a weak anchoring boundary, we investigate experimentally the rotation property of surface nematic director by electric field on non-treated Poly-Methylmethacrylate (PMMA, $T_g=110^{\circ}C$, Sigma Aldrich) film observed under various temperatures including the glass transition temperature ($T_g$) of the polymer layer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.852-859
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• 2005

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and Nose-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion and friction forces on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.353-355
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• 2010

Poly(methyl methacrylate) (PMMA) particles were prepared by soap-free emulsion polymerization of MMA in the presence of a cationic initiator, 2,2'-azobis(2-methylpropionamidine) (AIBA). The Stober method has been adopted to coat silica on the surface of these cationic particles. Negatively charged silica precursors were coated onto cationic particle surfaces by electronic interaction. During the coating process, hollow particles were directly obtained by dissolution of PMMA.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.964-970
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• 2002

We synthesized three kinds of chromophores incorporating aromatic quinoline unit as a $\pi-conjugated$ bridge in order to prepare more thermally stable nonlinear optical (NLO) chromophores than general stilbene unit. The NLO poly(methylmethacrylate) copolymer, polyimides, and polyester were successfully synthesized by these corresponding quinoline-based monomers. Their physical and optical properties were investigated by thermogravimetry, gel permeation chromatography, ultraviolet-visible spectroscopy, second harmonic generation (SHG) and electro-optic (EO) measurement. All the polymers exhibited better thermal stability,however their NLO activity was a little lower than that of general stilbene-based NLO polymers. Among three kinds of polymers, the PMMA copolymer with quinoline chromophores had the largest SHG coefficient d33 value of 27 pm/V (at 1.064 $\mu\textrm{m})$ and EO coefficient r33 value of 6.8 pm/V (at 1.3 $\mu\textrm{m}$).

• Journal of the Korean Chemical Society
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• v.14 no.1
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• pp.29-35
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• 1970

Chacterization of MMA/AN organosol copolymer and subsequent comparison with the prior art latex copolymers has been accomplished. By means of NMR analyses, we found both types of copolymers to be random. The GPC analyses show that the organosol copolymers have a singnificantly broader MW spread than latex copolymers. This is due to the low MW stabilizer which is present as a physical mixture. As a result, the MW distribution is bimodal. Fractionation of a typical organosol copolymer yields a low MW(33,000-100,000), MMA rich fraction and a high MW (250,000-330,000), AN rich fraction. Solubility-wise, the organosol copolymers are readily soluble in the lacquer solvent MEK to give a colorless film. The prio rart copolymers, hewever, were imcompletely soluble and gave yellow, hazy film.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.83-88
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• 2001

This study was preformed by measuring the minimum ignition temperature of MBS according to the change of sample vessel size and the minimum ignition temperature of MBS dust cloud The minimum ignition temperature of MBS product decreased as the vessel size was large, and it was obtained in the range from $120.5^{\circ}C$ to $94.5^{\circ}C$ and the apparent activation energy was obtained with 32.94Kcal/mol. The minimum ignition temperature of MBS dust cloud was measured by using Godbert-Greenwald furnace and it was obtained at $407^{\circ}C$ with the sample of 0.4g in the air and the ignition of dust cloud was not occurred below 13% oxygen concentration.