• Corrosion Science and Technology
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• v.6 no.5
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• pp.261-268
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• 2007

Embedded sensors were used as an in-situcorrosion-sensing device for aircraft and vehicular structures protected by organic coatings. Results are presented changes associated with a standard Airforce aircraft coating and a standard Army vehicle coating were monitored by embedded sensors. These coatings consisted of a polyurethane topcoat and an epoxy primer, however are formulated to provide different characteristics. The ac-dc-ac testing method was used to accelerate the degradation of these coatings while being immersed in a NaCl medium. Electrochemical impedance spectroscopy and electrochemical noise measurement experiments were used to monitor the induced changes. A comparison of the results between coatings subjected to the ac-dc-ac exposure and coatings subjected to only constant immersion in the NaCl medium is presented. The results were used to demonstrate the effectiveness of the ac-dc-ac method at accelerating the degradation of an organic coating without observably changing the normal mechanism of degradation. The data highlights the different features of the coating systems and tracks them while the coating is being degraded. The aircraft coating was characterized by a high-resistant topcoat that can mask corrosion/primer degradation at the primer/substrate interface whereas the vehicle coating was characterized by a low-resistant topcoat with an effective corrosion inhibiting primer. Details of the ac-dc-ac degradation were evaluated by using an equivalent circuit to help interpret the electrochemical impedance data.

• Corrosion Science and Technology
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• v.12 no.5
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• pp.253-258
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• 2013

Effects of copper hydroxide(II) on the curing and the corrosion resistance of electrocoating were investigated by MEK rubbing test, electrochemical impedance spectroscopy (EIS) and Thermo-gravimetric analysis (TGA). Curing performance of electrocoating was lowered with increasing the content of copper hydroxide(II) as evidenced by the MEK rub performance which decreased with increasing the content of copper hydroxide(II). This indicates copper hydroxide(II) affected the blocked isocyanate reaction in the coatings, by the decomposition of copper hydroxide(II) to CuO and $H_2O$ during reaction of isocyanate with nuclephiles. Corrosion resistance of coatings also decreased with the content of copper hydroxide. This reflects the higher barrier property in coatings with higher curing performance.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.356-363
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• 2012

In this study we synthesis Hybrid resin(WPC) by milk casein and waterborne polyurethane(WPU). Then we experiment how casein effect to Hybrid resins in Full-Grain leather coatings. According to measured data for solvent resistance, WPU resin and Hybrid resins had good property. As test of tensile strength, WPU had most low strength(2.130 $kg_f/mm^2$) and WPC-3(WPU 91: casein resin 9) had most high strength(2.191 $kg_f/mm^2$). Also we knew that most good property of abrasion is WPC-3(50.090 mg.loss). In elongation case, WPU had most good result(637 %) in this experiment.

• KIEAE Journal
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• v.16 no.6
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• pp.95-101
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• 2016

Purpose: This study aims to identify the effect of temperature reduction by the application of cool roof coatings to Changwon City Hall in South Gyeongsang Province. The indoor and outdoor temperatures of the cool roofing building were analyzed and compared to that of an existing building with green-colored roof coated with waterproof polyurethane. Method: The surface temperatures and reflectivity of rooftops, surface temperatures of ceilings and the interior, and outdoor temperature and humidity of the two aforementioned buildings were measured from June to September in 2014. The measurements were taken every 10 min. Result: The surface temperature of the building with the cool roof was lower by a maximum of $9^{\circ}C$ with the reflectivity of the rooftop at an average of 0.55, which is higher than that of the building with green polyurethane by approximately 0.3. The temperature of the ceiling inside the building with the cool roof was about $1{\sim}2^{\circ}C$ lower than that of the ordinary building. Also, the indoor temperature of the office with cool roof coatings was about $0.5{\sim}1.0^{\circ}C$ lower than that of the office with green-colored roofing building. The results show that cool roof coatings can lower the temperature of buildings. In the next research, the reduction in consumption of energy for air conditioning will be investigated by utilizing building energy simulation tools.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.907-913
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• 1997

Alkyd modified polyester was synthesized by the polycondensation of 1,4-butanediol, trimethylolpropane, adipic acid, and the intermediate obtained by the esterification of 3,5,5-trimethylhexanoic acid(THA) and trimethylolpropane, where the contents of THA as a component of alkyd polyol in the intermediate were changed according to 10, 20, and 30wt%, respectively. Two-component polyurethane coatings were prepared by blending the synthesized alkyd modified polyester with Desmodur L-75 as a component of polyisocyanate. Various tests for coating properties with the prepared coatings show that high fineness of grind of $8^-$point, short drying time of 2~3 hours, and long pot-life of 18~23 hours were observed with the content of 3,5,5-trimethylhexanoic acid.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.25-32
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• 2002

Two PU flame-retardant coatings, 2,3-DBPO/N-l00 (DBPON) and 2,3-DBPO/IL (DBPOI), were prepared by curing 2,3-dibromo modified polyester (2,3-DBPO) with isocyanate curing agent Desmodur N-l00 (or Desmodur IL) at room temperature. The physical properties and flame-retardancy of the two coatings were tested and compared. As a result, the pot-life, yellowness index, lightness index difference, $60^{\circ}$ specular gloss, cross-hatch adhesion, viscosity, and accelerated weathering resistance of DBPON were better than those of DBPOI; the fineness of grind of the two coatings were the same; and the drying time, hardness, and abrasion resistance of DBPOI were better than those of DBPON. The flame retardancy of the flame-retardant coatings increased with the content of the flame retarding component, 2,3-dibromopropanoic acid (2,3-DBP); and the LOI values of the two coatings were in a range of $27{\sim}29%$ when the content of 2,3-DBP was 30wt%.

• Elastomers and Composites
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• v.39 no.1
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• pp.71-76
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• 2004

4,4'-Methylenebis(2-chloroaniline)(MOCA) has been widely used as a crosslinking agent, but classified as a toxic chemical. Thus, its use will be limited in the near future. In this research, polyurethane coating films were prepared using 1,3-propanediolbis(4-aminobenzoate)(PDBA) as an alternative to MOCA. The base part was prepared by melting MOCA or PDBA in polyoxypropylene($M_n$=2000), followed by the addition of the various additives. The NCO-terminated toluene diisocyanate prepolymer was used as a curing agent. The polyurethane coating films were prepared by mixing the base part with the curing agent in an appropriate ratio at room temperature. The polyurethane coatings prepared using PDBA exhibited higher initial viscosity, but much longer pot lift, compared to those prepared using MOCA under the same conditions, due to lower reactivity of PDBA. The tensile strength and tear strength of the coating films were much weaker. However, the pot life, tensile strength, elongation, and tear strength of the coating films, prepared using PDBA in the presence of an increased amount of Pb(II)-octoate, were close to those of the coating films prepared using MOCA. Thus, it was concluded that PDBA can substitute MOCA in the preparation of polyurethane coatings as long as the reactivity of PDBA is enhanced using appropriate amounts of the catalyst or other appropriate catalyst.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.1-8
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• 2013

The present approach shows the use of nano-silica/nano-alumina in polyurethane (PU) matrix, which lead to significant improvements in the mechanical and thermal properties of the nano-composite. It is observed that with incorporation of 1% of nano-alumina into the PU matrix, there is an improvement in the tensile strength of around 50%, and for nano-silica the improvement is around 41%, at the same concentration. The morphological data shows that above 3% of the nano particles there are agglomerations in the nanocomposite. Again with the absorption of moisture, there is a decrease in the thermal and mechanical properties of the PU resin, but in this research work it is observed that with the incorporation of the nano particles, in the presence of absorbed moisture there is an improvement in mechanical and thermal properties of the composite, over that of the PU matrix.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.711-718
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• 2014

In this paper, the mechanical property change was investigated by adding 1,4-butanediol as chain extender of polyurethane dispersion for leather coating. Reagents for the synthesis were polypropylene glycol(PPG), isoporon diisocyanate(IPDI), dimethylolpropionic acid(DMPA) and 1,4-BD. All samples showed good solvent resistance and flexibility by different content of the 1,4-BD. As results, samples which contains a lot of 1,4-BD showed good properties whth strength of $1.80kg_f/mm^2$ and abrasion test measurement of 49.54 mg.loss. According to elongation test, the sample which contains low amount of 1,4-BD was good property as 364 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1773-1777
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• 2010

The Application of UV curing technique for poly (vinyl chloride) (PVC) floor tiles coating has improved the quality of PVC floor. Several formulations were made including acrylated oligomers based on a polyurethane were blended with reactive monomers, photoinitiators and other additives. The used oligomers are commercial aliphatic urethane acrylates. Thin films were prepared on PVC tiles by bar coating with different formulations using UV radiation. The coating resins were characterized by FTIR. The properties of UV-cured films such as gloss and adhesion were examined. The properties of UV-cured films dependent on the influence of composition and processing conditions was studied.