• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1121-1126
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• 2000

The purpose of this study is to clarify chemical resistance of polymer-cement slurry coated reinforcing bars. Polymer cement slurry coated reinforcing bars were showed the good state to the bending resistance, impact resistance, adhesive strength, but exact data of the chemical resistance do not exist. Through the experimental, it is to certify chemical resistance of polymer cement slurry coated reinforcing bars. In this study, polymer cement slurry coated reinforcing bars are prepared with two types of polymer, polymer-cement ratios of 50%, 100%, 150%, coating thickness, curing periods of 3, 7, 28days, and tested for chemical resistance as KS(Korea Standard). From the test results, chemical resistance of polymer cement slurry coated reinforcing bars used by acrylic and St/BA emulsion were showed excellent without concerned polymer-cement ratios, curing period except for 1% aqueous solution $H_2SO_4$. But polymer cement coated reinforcing bar used by acrylic emulsion is inferior to aqueous solution NaOH.

• Polymer(Korea)
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• v.39 no.3
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• pp.403-411
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• 2015

A series of hydrophobically associating fluorinated amphiphilic polyacrylamide copolymers with remarkably high heat resistance and salt tolerance were synthesized by free radical micellar copolymerization, using acrylamide (AM) and sodium 2-acrylamido-tetradecane sulfonate ($AMC_{14}S$) as amphiphilic monomers, and 2-(perfluorooctyl) ethyl acrylate (PFHEA) as hydrophobic monomer. The structure of the terpolymer was characterized by FTIR, $^1H$ NMR and $^{19}F$ NMR. The solution properties of the terpolymers were investigated in details, and the results showed that the terpolymer solution had strong intermolecular hydrophobic association as the concentration exceeded the critical association concentration 1.5 g/L. The terpolymer solution possessed high surface activity, viscoelasticity, excellent heat resistance, salt tolerance and shearing resistance. The viscosity retention rate of copolymer solution was as high as 59.9% under the condition of fresh wastewater, $85^{\circ}C$ and a 60-days aging test.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.183-186
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• 1998

This paper deals with 28, 56, 91 days age compressive strength and ratio of weight when OPC and Low-Heat cement mortar immersed in chemical solution. As a result of experiment, the resistance of Low-Heat Cement motar in chemical attack is more effective than that of OPC, because of lower $C_3$A content and Pozzolanic reactions. Especially in long term age compressive strength, Low-Heat cement mortar shows higher strength in all kind of chemical solution compared with compressive strength of OPC motar.

• Journal of the Korean Wood Science and Technology
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• v.36 no.2
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• pp.73-78
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• 2008

Inorganic chemical treated wood was prepared by impregnation of calcium or magnesium chloride ($CaCl_2$ or $MgCl_2$) solution and immersion in saturated solution of ammonium fluoride ($NH_4F$) as a reactant in order to make an introduction of a refractory fluorides with fungicidal and insecticidal effects in wood. The weight percent gains (WPGs) were increased with increase in concentration of calcium chloride or magnesium chloride solution, and were higher in treatment with calcium chloride than with magnesium chloride. Inorganic substances were produced mainly in the lumina of tracheides. These substances were proved to be the calcium fluoride or magnesium fluoride by the energy dispersive X-ray analyzer in conjunction with a scanning electron microscope (SEM-EDX). The treated wood showed good decay resistance because the weight losses were hardly occurred by the test fungi such as Tyromyces palustris and Trametes versicolor. The fire resistance effect was superior to the treated wood compared with that of the untreated wood.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2A
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• pp.105-113
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• 2011

This study evaluated the effects of fibers on the mechanical properties and chemical solution resistance of porous concrete with fiber type (jute, pulp, PVA and nylon fiber) and fiber volume fraction (0.0%, 0.1%, 0.2%, 0.3%). The tests that were carried out to analysis the properties of porous concrete included compressive strength, void ratio, pH value, and chemical solution exposure with varying type and volume fraction of fiber were conducted. The type and volume fraction of fiber also affected the void ratio, compressive strength, flexural strength and chemical solution exposure. Increased volume fractions of fiber resulted in improved properties of the compressive strength, flexural strength and void ratio. However, the difference between the measured pH value and chemical resistance of porous concrete with fiber type and volume fraction was not significant.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.151-154
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• 2002

The durability of two kinds of CFRP plates, carbon/UP and carbon/V, was studied under severe environmental conditions. Immersion into the chemical solutions and accelerated weathering were executed on the CFRP plates and the weight change under each condition was measured. After those treatments, the plates were tested by tensile testing machine to measure the mechanical properties and observed by SEM to find the damage behaviour of the surface. Comparing the virgin plates and the chemically exposed plates, both plates show severe deterioration of the mechanical properties. But, the plates subjected to alkali solution show much larger reduction than those of acidic solution and carbon/V has better chemical resistance than carbon/UP. The material properties of CFRP plate exposed to the weathering were deteriorated linearly proportional to the exposure time.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.475-479
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• 2000

A possibility of the implementation of a quartz crystal sensor to the determination of chemical oxygen demand is examined by checking the electrochemical behavior of the sensor in a glucose solution. Since the surface of a quartz crystal has to be oxidized, a relatively active metal is coated on the surface of a usual 9 MHz AT-cut crystal. The electrochemical behavior is investigated by measuring the changes of current, resonant frequency and resonant resistance while a constant potential is applied. The crystal is installed in a specially designed container, and a quartz crystal analyzer is utilized to measure the frequency and resistance simultaneously. The variations of the measurements are examined at different concentrations of glucose solution, and a proper relation between the concentrations of glucose solution, and a proper relation between the concentration and the measurements is analyzed. As a result, it is found that a linear relation between the concentration of less than 900 ppm and the peak current when a constant potential of -180 mV (SSCE) is applied. The relation can be utilized for the determination of glucose concentration in sea water, and considering a direct relation between gluose concentration and chemical oxygen demand tells a possibility of the measurement of chemical oxygen demand using quartz crystal oscillators.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.231-241
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• 2021

The objective of this study was to evaluate total current under steady-state conditions for a material undergoing corrosion using the electrochemical frequency modulation (EFM) technique, taking into account the presence of solution resistance and double layer capacitance. The analysis involving linearization of the Tafel curve allowed for the estimation of corrosion parameters. Results showed that the output signal was dependent on fundamental frequencies and their multiples. In addition, the output signal almost manifested itself at frequencies that were sums of fundamental frequencies of the applied sinusoidal signal. The harmonics calculated showed a significant shift from the principal frequency of input signals. The investigation involved the influence of corrosion current and anode-to-cathode Tafel slope ratio on faradaic and non-faradaic currents (including the average and RMS). The model presented showed both qualitative and quantitative improvements over the previously developed EFM technique that ignored the influence of solution resistance and the double layer capacitance while assuming the applied DC potential corresponded to the corrosion potential of the corroding material.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.265-266
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• 2006

The chemical conversion coating formed on magnesium alloy investigated for low cost and harmless in environment by using the colloidal silica as the main component. The film formed in 298 K is thick, the film, which was thought combination of Si-O, was formed. The film formed in 313 K is thinner than that in 298 K. The quantity of film formed at high temperature such as 333 K and 353 K is smaller than dissolved quantity. At the anodic polarization experiment, corrosion resistance in sealing by hot water after chemical conversion treatment in basic solution condition get worse than that in comparison with basic solution condition. In salt spray test, the ratio of black rust on specimen that did not conducted chemical conversion treatment was five times or more compared with those of chemical conversion treated specimen. The film thickness of chemical conversion coating produced by alkali treatment process is thinner than in comparison with that of specimen produced in basic chemical conversion treatment solution condition. It is thought, however, that it showed good corrosion resistance during salt spray test because the area of microcracks is small.

• Corrosion Science and Technology
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• v.14 no.5
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• pp.207-212
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• 2015

The purpose of this research was to synthesize fluorine modified waterborne polyurethane dispersion (F-WPU) by soap-free (internal emulsifier) emulsion polymerization techniques, to prepare coating solution based on fluorine modified waterborne polyurethane dispersion (F-WPU) and to compare the chemical and thermo-mechanical properties on the electrogalvanized steel sheet. Environmentally friendly F-WPU was prepared with a fluorinated polyol containing 60 wt% of fluorine. There are various ways of combining a wide variety of fluorinated polyols and diisocyanate to exhibit novel properties of waterborne polyurethane dispersion. Components of coating solution were largely divided into 4 kinds i.e., F-WPU, acrylic emulsion, silane coupling agent, and colloidal silicate. F-WPU coating solution on the electro-galvanized steel sheet showed excellent properties of corrosion resistance, alkali resistance and heat resistance, as compared to other coating solutions using a general waterborne resin. The F-WPU coating solution's reliable effects are possibly due to the fluorine atoms incorporated even in a small amount of F-WPU.