• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.397-402
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• 2005

Core-shell Poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAm) was prepared by soap-free emulsion polymerization of styrene (St) and N-isopropylacrylamide (NIPAm) in aqueous solution with potassium persulfate (KPS) as an initiator. The effects of St/NIPAm ratio, concentrations of monomer and crosslinker were studied. Also, Thermo sensitivity of microgels prepared was investigated. Particle size of microgels increased with increasing mol ratio of NIPAm to styrene. Transmittance of the microgel dispersion decreased rapidly when heated above a low critical solution temperature (near $32{\sim}34^{\circ}C$, cloud point). Swelling ratio of the microgel increased with increasing of the concentration of monomer (NIPAm) and decreased proportional to the concentration of crosslinker.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.191-199
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• 2005

Removable protective adhesives for automobiles were synthesized by an emulsion polymerization of monomers such as n-butyl acrylate (BA), n-butyl methacrylate (BMA), acrylonitrile (AN), acrylic acid (AA) and 2-hydroxyethyl methacrylate (2-HEMA), in which AA and 2-HEMA were functional monomers. Potassium persulfate (KPS) was used as an initiator and sodium lauryl sulfate (SLS) was used as an emulsifier, and polyvinyl alcohol (PVA) was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch type reactor. Tensile strength, extension, peel strength, viscosity and solid content of the synthesized adhesives were tested. The optimum physical properties of the removable protective adhesives for automobiles were obtained with the composition of 0.43 mole BA, 0.57 mole AN, 0.21 mole BMA, 0.03 mole AA, and 0.03 mole 2-HEMA.

• Journal of the Korean Applied Science and Technology
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• v.23 no.2
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• pp.169-176
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• 2006

Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at $70^{\circ}C$ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.13-19
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• 2001

An on-line digestion system based on the flow injection analysis technique was presented for the determination of total phosphorus. The system converts condensed and organic phosphoruses into orthophosphate that can be analyzed spectrophotometically. The reaction between orthophosphate and ammonium molybdate in a strong acid medium forms the yellow complex of phosphomolybdate which is next reduced to a molybdic blue complex by stannous chloride. The quantitation of orthophosphate is based on the absorbance of the molybdic blue. To determine total phosphorus, the digestion system was installed between the sample injector and the reaction coil with the added lines of digestion solution(potassium persulfate+sulfuric acid) and the $H_2O$ carrier. The system has shown that the digestion efficiencies were greater than 95% for the typical condensed and organic phosphoruses. When tripolyphosphate standards were used, the calibration data showed that the linear dynamic range extended to a concentration of 1.5ppm with the detection limit of 25ppb total phosphorus. The typical relative standard deviation was less than 2%. The proposed system was successfully applied to lake water, wastewater, and streamwater. The analytical variables such as digestion efficiency, analysis time, and reproducibility were evaluated and compared with the manual digestion method.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.485-494
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• 2008

The acrylic coating emulsions were prepared by the emulsion polymerization to protect the surface of steel plate from the corrosion chemicals like acid, base and salt water. MMA(methyl methacrylate), styrene, BA(butyl acrylate), and 2-HEMA(2-hydroxyethyl methacrylate) were used as monomer. KPS(potassium persulfate) and SBS(sodium bisulfite) as redox initiator and SDBS(sodium dodecylbenzene sulfonate) as emulsifier were used on the emulsion polymerization reaction. The most stable in-situ coating was obtained when 10% of MMA was added. Both particle size and quantity in emulsion were decreased as increasing the mount of SDBS. the most stable prepared coating emulsion with polyisocyanate crosslinker showed very high anticorrosion properties on the coated steel layer to salt water, whereas no significant improvement of anticorrosion property to acdic and basic condition it showed.

• Journal of the Korean Applied Science and Technology
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• v.22 no.4
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• pp.332-338
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• 2005

This study was conducted to prepare acrylic removable protective coatings by emulsion polymerization. Monomers used were n-butyl acrylate, acrylonitrile, butyl methacrylate. Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at $70^{\circ}C$ and agitation speed was 200 rpm. Tensile strength, extension, peel strength, viscosity, and solid contents of the synthesized coatings were examined. The coatings prepared with BA:AN = 60:20 (in weight ratio) satisfied the standard for automobile in terms of extension and peel strength. When the concentration of BMA was in a range of $18{\sim}23$ wt%, the prepared coatings satisfied the standard for automobile in terms of peel strength and water resistance.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.183-187
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• 2010

Core-Shell polymers of silicone dioxide-styrene system were prepared by sequential emulsion polymerization. In inorganic/organic Core-Shell composite particle polymerization, silicone dioxide adsorbed by surfactant sodium dioctyl sulfosuccinate (EU-DO133L) was prepared initially and then core silicone dioxide was encapsulated emulsion by sequential emulsion polymerization using styrene at the addition of potassium persulfate (KPS) as an initiator. We found that $SiO_2$ core shell of $SiO_2$/styrene structure was formed when polymerization of styrene was conducted on the surface of $SiO_2$ particles, and the concentration sodium dioctyl sulfosuccinate (EU-DO133L) was 0.5~2.0g. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• Macromolecular Research
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• v.13 no.6
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• pp.483-490
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• 2005

A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan ($_{k}C$), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for $_{k}C$­g-polymethacrylic acid ($_{k}C$-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of super absorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

• Macromolecular Research
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• v.11 no.1
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• pp.14-18
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• 2003

Grafting of glycidyl methacrylate (GMA) upon coralline hydroxyapatite in conjugation with demineralized bone matrix (CHA-DBM) using equal molar ratio of potassium persulfate/sodium metabisulfite redox initiating system was investigated in aqueous medium. The optimum reaction condition was standardized by varying the concentrations of backbone, monomer, initiator, temperature and time. The results obtained imply that the percent grafting was found to increase initially and then decrease in most of the cases. The optimum temperature and time were found to be 50 $^{\circ}C$ and 180 min, respectively, to obtain higher grafting yield. Fourier transform infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD) method were employed for the proof of grafting. The FT-IR spectrum of grafted CHA-DBM showed epoxy groups at 905 and 853 $cm^{-1}$ / and ester carbonyl group at 1731 $cm^{-1}$ / of poly(glycidyl methacrylate) (PGMA) in addition to the characteristic absorptions of CHA-DBM, which provides evidence of the grafting. The XRD results clearly indicated that the crystallographic structure of the grafted CHA-DBM has not changed due to the grafting reaction. Further, no phase transformation was detected by the XRD analysis, which suggests that the PGMA is grafted only on the surface of CHA-DBM backbone. The grafted CHA-DBM will have better functionality because of their surface modification and hence they may be more useful in coupling of therapeutic agents through epoxy groups apart from being used as osteogenic material.

• Journal of the Korean Applied Science and Technology
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• v.19 no.2
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• pp.131-136
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• 2002

As model waterborne acrylic coatings, mono-dispersed poly(butyl acrylate-methyl methacrylate) copolymer latexes of random copolymer and core/shell type graft copolymer were prepared by seeded multi-staged emulsion polymerization with particle size of $180{\sim}200$ nm using semi-batch type process. Sodium lauryl sulfate and potassium persulfate were used as an emulsifier and an initiator, respectively. The effect of particle texture including core/shell phase ratio, glass transition temperature and crosslinking density, and film forming temperature on the film formation and final properties of film was investigated using SEM, AFM, and UV in this study. The film formation behavior of model latex was traced simultaneously by the weight loss measurement and by the change of tensile properties and UV transmittance during the entire course of film formation. It was found that the increased glass transition temperature and higher crosslinking degree of latex resulted in the delay of the onset of coalescence of particles by interdiffusion during film forming process. This can be explained qualitatively in terms of diffusion rate of polymer chains. However, the change of weight loss during film formation was insensitive to discern each film forming stages-I, II and III.