• 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.

• Polymer(Korea)
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• v.27 no.5
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• pp.421-428
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• 2003

The kinetics of photoinitiated polymerization of reactive oligomer methacrylates and oligomer methacrylate/SBS blends have been studied to characterize the diffusion-controlled reaction using Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (ATR-FTIR). The polymerization rates of reactive oligomer methacrylates and oligomer methacrylate/SBS blends were autocatalytic in nature at the initial stage and then a retardation of the reaction conversion occurred gradually as the polymer matrix became vitrified, and finally the reaction became diffusion controlled. Photopolymerization behavior of methacrylate/SBS blends was well predicted using the diffusion-controlled reaction model. N-Vinyl-2-pyrrolidinone (NVP) as a reactive solvent was used to incorporate SBS into methacrylate to form semi-IPN via photopolymerization. Due to the high reactivity of NVP, polymerization rate increased with the increase of NVP content. As the content of NVP-SBS in the blends increased up to 10 phr, the reaction conversion maintained almost constant. But above 20 phr of NVP-SBS in the blends, the reaction conversion gradually decreased since the increase of viscosity affected on the photopolymerization rate. The semi-IPN films of methacrylate/SBS blends were transparent at room temperature as well as at increased temperature and were able to be applied to surface coating.

• Clean Technology
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• v.18 no.2
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• pp.123-143
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• 2012

Supercritical fluid technology (SFT) is recently one of the most new techniques, which has been interested various fields of related chemical industries. SFT is the most effective and practical technology with eco-friendly, energy-savings, and high efficiency as the technique using the advantages of supercritical fluid such as high solvation power, solubility, mass transfer rate, and diffusion rate. Especially, it is necessary to analyze, evaluate, and develop the potential of application techniques using SFT with these characterizations. Therefore in this review, the phase behavior in supercritical fluid at high temperature and pressure of monomers/polymers for the optimization of polymerization process are briefly described, and the preparation of molecularly imprinted polymers (MIPs) in supercritical fluid using supercritical polymerization and the performance evaluation of MIPs are introduced.

• Polymer(Korea)
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• v.32 no.1
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• pp.38-42
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• 2008

Ultrathin films were coated on low density Polyethylene (LDPE) food packaging films by plasma polymerization of methane, acetylene, hexamethyldisiloxane (HMDSO), and HMDSO+oxygen to improve the barrier property of the LDPE films. The film coated in HMDSO +oxygen (flow rate: 0.6+ 9.0 SCCM) plasma at 40 W for 10 min showed the highest improvement in the barrier property against oxygen, reducing the permeability of oxygen as much as 18.6 times. The film coated in acetylene (flow rate 0.75 SCCM) plasma at 10 W for 10 min showed the highest improvement in the barrier property against carbon dioxide and moisture, reducing the permeability of carbon dioxide and moisture as much as 12.0 and 3.0 times, respectively. In addition, cherry tomato, cucumber, and mushroom (Flammulina velutipes) wrapped with the coated films were kept fresh $1.5{\sim}3.0$ times longer than those wrapped with an LDPE film.

• Journal of the Korean Ceramic Society
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• v.24 no.2
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• pp.133-138
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• 1987

The behavior of CaO and SiO2 in the reaction produced which produced in the early hydration of C3S was studied by XRD and thermal analyzer. Polymerization of hydrated siltcates was also studied by TMS method. TMS derivatives were separated by gaschromatography. Cao/SiO2 molar ratios of the produced CSH gel under the air atmosphere were higher than that in the CO2. Dimerization rate of hydrated silicates was very fast in the early hydration stage. Trimer began to appear later than dimer and its increasing rate was very low. The amount of dimer and trimer formed under the CO2 atmosphere was less than that in the air.

• Polymer(Korea)
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• v.28 no.1
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• pp.10-17
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• 2004

Poly(vinyl acetate) (PVAc) nanoparticles were synthesized in oil/water miniemulsion polymerization in the presence of low amount of hexadecane as a cosurfactant. The nanoparticles were tested to apply as a drug carrier. The shape of nanoparticles was observed by scanning electron microscopy, and the average particle size and size distribution were examined by particle size analyzer. Inclusion of antibiotic drugs into the nanoparticles was confirmed by CHO, C=O, and OH peak of FT-IR. Size of the nanoparticles were adjusted between 80∼300 nm by changing the homogenization rate and amount of cosurfactant and surfactant. The monomer droplets prepared by miniemulsion method using a cosurfactant were homogeneous and stable compared with those prepared by conventional emulsion polymerization. This might be occurred due to the prevention of Ostwald ripening and coalescence between droplets by using hexadecane as a cosurfactant.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.378-381
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• 2014

We studied the pasteurization effect of the microorganism involved in the water, using ion-exchanging filter made of the Radiation Induced Grafted Polymerization. This ion-exchanging filter is made by the graft polymerization of GMA, after irradiation of electron beam to the non-woven filter. Then, we made the ion-exchanging filter (EtA, DEA, SS) applying ion-exchanging base to the GMA filter. As a result, the density of the ion-exchanging base is shown as 2.38 mol/kg in case of EtA, 1.79 mol/kg in case of DEA and 0.75 mol/kg in case of SS. Through this filter made by this method, we measured the pasteurization power of E. coli. We found very high elimination rate such as log 4.65 in case of SS-dial filter, which is higher as 3.00 times in comparison with EtA, and 1.10 times in comparison with DEA. This data show the result is very excellent comparing with 3,000 CFU/ml. of city water treatment basis.

• Elastomers and Composites
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• v.53 no.3
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• pp.158-167
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• 2018

In this study, in-situ trans-selective polymerization of isoprene was carried out using titanium-based Ziegler-Natta catalysts. The catalysts were prepared by high-energy ball milling. Individually Large-inner-diameter carbon nanotubes (CNTL), and hydroxylated carbon nanotubes (CNTOH), along with magnesium chloride ($MgCl_2$) were used as the carriers for the catalysts. The optimum ball-milling time for preparing the $CNT/MgCl_2/TiCl_4$ Ziegler-Natta catalysts was 4 h. The $CNTOH/MgCl_2/TiCl_4$ catalyst showed a higher efficiency than that of the $CNTL/MgCl_2/TiCl_4$ catalyst, based on the rate of polymerization. The effects of the CNT-filler type on the isoprene polymerization behaviors and polymer properties were investigated. The morphologies of the trans-1,4-polyisoprene (TPI)/CNT and TPI/CNTOH nanocomposites exhibited a tube-like shape, and the CNTL and CNTOH fillers were well dispersed in the TPI matrix. In addition, the thermal stability of TPI significantly increased upon the introduction of a small amount of both CNTL/CNTOH fillers (0.15 wt%), owing to the satisfactory dispersion of the CNTL/CNTOH in the TPI matrix.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.213-219
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• 1997

The plasma polymerized styrene films were prepared by using an inter-electrode capacitively coupled gas-flow-type reactor, and the effects of plasma polymerization condition on the molecular weight distribution were investigated by Fourier Transform Infrared (FT-IR), Pyrolysis Gas Chromatography(PyGC), Differential Scanning Calorimetry(DSC) and Gel Permeation Chromatography(GPC). From the above results, the very cross-linked films different from chemical characteristics of the starting monomer were taken out, and it is realized that the molecular structure, cross linking density, and molecular weight distribution could be controlled by changing the parameters such as deposition pressure, deposition power and gas flow rate. Accordingly, it is suggested that plasma polymerization method performed by inter-electrode capacitively coupled gas-flow-type reactor has good characteristics for manufacturing the functional organic thin films which can be applied in sensors, opto-electric device, photo-resist by changing the polymerization parameters.

• Polymer(Korea)
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• v.36 no.1
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• pp.65-70
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• 2012

Glycidyl methacrylate (GMA) was used to introduce epoxy groups on the surface of polypropylene (PP) plate, used as a substrate, through plasma-induced graft copolymerization. Emulsion polymerization was applied for graft copolymerization of GMA and was compared with conventional solution polymerization to confirm its effect. Plasma treatment conditions under one atmospheric pressure were fixed as follows; the RF power of 200 W, the treatment time of 30 sec, the Ar gas flow rate of 6 LPM, and the exposure time of treated PP samples in air of 5 min. For graft-copolymerization, GMA concentration, reaction temperature, and reaction time was optimized to maximize the grafting degree of GMA. The maximum grafting degree of GMA was obtained at the condition of 12%-GMA concentration, $90^{\circ}C$ reaction temperature, and 5 hr-reaction time. Analysis results supported that the emulsion polymerization was more effective than the solution polymerization for grafting more GMAs on the surface of PP plate under the same reaction conditions.