• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.451-458
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• 2014

Waterborne polyurethane dispersion (WPUD) was prepared from polycarbonate diol (PCD), isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) as starting materials. Then, waterborne acrylic polyurethane dispersion (AUD) was synthesized by reacting the WPUD with different types of acrylate monomers, such as methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA) and butyl acrylate (BA). Subsequently, the AUD was mixed with multi-walled carbon nanotube (MWCNT) to yield a conductive coating solution, and the mixture was coated on the polycarbonate substrate. The pencil hardness, abrasion resistance and chemical resistance of the coating films from AUD were improved than those from WPUD, while the electrical conductivity of the coating films from AUD was decreased than that of WPUD. Also, the effect of acrylate types on the properties of coating films was investigated. The AUD obtained from HEMA showed the strongest pencil hardness, while the AUD obtained from MMA exhibited the strongest abrasion resistance, chemical resistance and electrical conductivity among several types of acrylate monomers.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.78-83
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• 2012

In this study, some experimental results of the peroxide-degradation process of polypropylene(PP) in a co-rotating twin-screw extruder to produce controlled rheology polypropylene(CRPP) are presented. The peroxide was dicumyl peroxide(DCP) and the concentration of DCP was in the range 0-0.3 wt%. It was found that the rheological properties of PP change significantly during reactive extrusion. Melt flow index(MFI) increased with DCP concentration. Intrinsic viscosity decreases with increasing DCP concentration. From dynamic rheological data, number average molecular weight(Mn), weight average molecular weight(Mn) and molecular weight distribution(MWD) were calculated. Results indicated that Mw decreases and MWD becomes narrower with increasing peroxide concentration. Especially, particle size distribution of CRPP decreases with increasing DCP concentration by chemical powdering process, and anti-slip floor paint, CRPP(DCP 0.2 wt%) powder by 10phr was friction coefficient 2.15 ${\mu}$, abrasion resistance 511.18%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.272-277
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• 2019

In this paper, a manufacturing method of an anti-glare cover glass on LCD for outdoor use is proposed. The main specification of cover glass is hardness and anti-glare. Hardness is achieved by using the tempered glass, and anti-glare(AG) film is laminated to meet anti-glare specification no the tempered glass. However, the AG film is difficult to maintain the AG performance continuously because the abrasion resistance of the PET film itself is as weak as about 3H. Therefore, a novel production procedure using screen printing method is proposed. The proposed coating is implemented by applying $ZnO-B_2O_3-SiO_2$ powder on glass surface and the glass is made with enhanced hardness through tempering process. In order to apply the ZBS powder uniformly on the glass surface, a screen printing process is used. The main parameters to be considered in screen printing are the oil concentration and mesh opening size. Because the amount of ZBS powder applied to the printing process is controlled by these two parameters, the correlativity is confirmed through the experiments. In order to evaluate the performance of the proposed method, the haze, surface roughness and transmittance are selected as the performance index and are compared with the AG film. As a result of comparison, it is verified that the transmittance of the proposed tempered glass is 83.1%, which is slightly lower than 89.5% of AG film, but the hardness is more than double to 7H.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.484-492
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• 2013

With the industrial acceleration in a lot of countries of the world, the demand for anti-corrosion and anti-abrasion material increases continuously. Particularly, stainless steel with the fine surface and excellent corrosion resistance is widely used in various industrial fields including ship, offshore structures tidal power plant, and etc. In marine environment, however, it is easy to generate by the corrosion damage by $Cl^-$ ion and cavitation damage due to high rotation speed on stainless steel. Therefore, in this research, the cavitation erosion-corrosion test (Hybrid test) was performed for 304 stainless steel specimen used in the high flow rate seawater environment. And the cavitation damage behavior in the corrosive environment was analyzed overall. The high hardness was shown due to the formation of compressive residual stress by the water cavitation peening effect in cavitation condition. However, high current density in the potentiodynamic polarization experiment presented with the breakdown of the passive film caused by physical impact. Therefore, both electrochemical characteristics and mechanical properties must be taken into account to improve the cavitation resistance in seawater.

• Elastomers and Composites
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• v.43 no.1
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• pp.8-17
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• 2008

Styrene-butadiene rubber(SBR) has good abrasion resistance, miscibility, and anti-vibration property. however, it is easily damaged by ozone and swelled by hydrocarbon fluids because of unsaturation part in main chain, that causes loss of visco-elasticity and reduction of product's life cycle. Therefore, object of this study is to cope with this problem. SBR is blended with various proportion of ethylene-propylene-diene terpolymer(EPDM), which has excellent ozone and oxygen resistance, to improve physical properties and ozone resistance, and diverse analytical techniques are used to measure morphology, glass transition temperature$(T_g)$, ozone-resistance, degradation temperature, static spring constant, hardness for considering a suitability for anti-vibration industrial product. We found that the blend consisting of SBR 70% and EPDM 30% showed no crack after ozone test and good miscibility between SBR and EPDM from this study.

• Corrosion Science and Technology
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• v.8 no.3
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• pp.126-131
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• 2009

The interaction between wear and corrosion can significantly increase total material losses in water chemistry environment. The corrosive wear tests of a PWR steam generator tube material (Alloy 690) against the anti vibration bar material (409 SS) were performed at room temperature. The tests were performed in alkaline water chemistry conditions. NaOH solution was selected for test condition to investigate the corrosive wear effect of steam generator tube material in alkaline pH condition without other factors. The flow induced vibration can caused tube damage and the corrosion can be occurred by water chemistry. The test results showed that, in the alkaline solution at pH 13.9, the corrosion current density was increased about ten times than that in the distilled water. And wear rate at pH 13.9 was increased about ten times from that at neutral condition. However, the wear rate was decreased with time. The decrease would be attributed to the change in roughness of specimen or sub-layer of the worn surface with time. From microstructure observation, severe abrasive shape and several wear debris were found. From those results, it could infer that the oxide film on Alloy 690 changed to easily breakable one in the alkaline water, and then abrasion with corrosion became the main wear mechanism.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.148-148
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• 2017

Surface modification is a type of mechanical manipulation skills to achieve extensive aims including corrosion control, exterior appearance, abrasion resistance, electrical insulation and electrical conductivity of substrate materials by generating a protective surface using electrical, physical and chemical treatment on the surface of parts made from metallic materials. Such surface modification includes plating, anodizing, chemical conversion treatment, painting, lining, coating and surface hardening; this study conducted cavitation experiment to assess improvement of durability using anodizing. In order to observe surface characteristics with applied current density, the electrolyte temperature, concentration was maintained at constant condition. To prevent hindrance of stable growth of oxide layer due to local temperature increase during the experiment, stirring was maintained at constant speed. In addition, using galvanostatic method, it was maintained at processing time of 40minutes for 10 to $30mA/cm^2$. The cavitation experiment was carried out with an ultra sonic vibratory apparatus using piezo-electric effect with modified ASTM-G32. The peak-to-peak amplitude was $30{\mu}m$ and the distance between the horn tip and specimen was 1mm. The specimen after the experiment was cleaned in an ultrasonic bath, dried in a vacuum oven for more than 24 hours, and weighed with an electric balance. The surface damage morphology was observed with 3D analysis microscope. As a result of the study, differences were observed surface hardness and anti-cavitation characteristics depending on the development of oxide film with the anodizing process time.

• Polymer(Korea)
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• v.35 no.2
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• pp.141-145
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• 2011

The electron beam (EB) induced curing of a typical resin designed for the hard coating layer of in-mold decoration foils was investigated. The samples were irradiated with different doses of EB and the curing reaction was monitored by Fourier transform infrared (FTIR) spectroscopy. The change in coating properties such as surface hardness and anti-abrasion property was studied as a function of increasing dose. The effect of the addition of nano-particles on the improvement of coating properties was also examined. It was expected that the experimental results could be used for the commercial exploitation of the EB curing system comparable to the ultraviolet (UV) curing system.

• Textile Coloration and Finishing
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• v.35 no.3
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• pp.151-158
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• 2023

In this study, we investigated the durability properties of the recycled leather using shaving scrap with antioxidant. Recycled leather sheets were manufactured by mixing shaving scrap and NB latex as a binder. HALS(Hindered Amine Light Stabilizer) and UVA(UV absorbers) were used as antioxidant. Mechanical properties such as hardness, tensile strength, elongation, tear strength and abrasion resistance were measured. Light aging resistance was evaluated using UV lamp and the degree of discoloration of the recycled leather sheets using a gray scale. In addition, to evaluate heat aging and UV aging, the degree of discoloration of the recycled leather sheets over time was measured using colorimeter. Washing fastness was evaluated on the degree of dyeing of recycled leather sheets for six type of multi-fiber woven fabrics (Acetate, Cotton, Nylon-66, Polyester, Acryl, Wool). To determine whether hazardous substances were detected in recycled leather sheets, the contents of arylamine and Cr 6⁺ were evaluated. As a result, when used in combination with antioxidant, the heat aging and light aging of recycled leather were improved and hazardous substance were not detected.

• Journal of Adhesion and Interface
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• v.2 no.2
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• pp.20-27
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• 2001

Recently polycarbonate material has been utilized as windows in aircraft, buildings, and optical lens. However, while polycarbonate has excellent optical transparency, impact strength and many beneficial mechanical properties, it possesses poor abrasion resistance and weatherability. Then, there is a need for developing optically clear, anti-abrasive and weather resistant hard coating agents for polycarbonate. In this study, N-triethoxy silyl propyl quinine urethane(TESPQU) was synthesized with quinine and 3-isocyanato propyl triethoxy silane(3-IPTES). In order to introduce optically active silane in the main siloxane network, TESPQU was co-hydrolysed and co-condensed with methyl triethoxy silane(MTES) under acidic conditions. Polycarbonate sheets were coated with silica coating agents by the sol-gel method, and their abrasion resistance, ability of UV absorption and weatherability were evaluated. Coating agents containing hydroxybenzophenone as a UV absorber were also prepared to compare weatherability with TESPQU containing coating agent. TESPQU containing coating agent had good weatherability in accelerated QUV test.