• Title, Summary, Keyword: chemical resistance

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Resistant Properties of Water-Borne Acrylic Pressure Sensitive Adhesives for Automobile Protection (자동차 보호용 수계형 아크릴 점착제의 내성)

  • Hahm, Hyun-Sik;Kwak, Yun-Chul;Hwang, Jae-Young;Ahn, Sung-Hwan;Kim, Myung-Soo;Park, Hong-Soo;Yoon, Cheol-Hun;Sung, Ki-Chun
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.3
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    • pp.289-297
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    • 2005
  • In order to improve resistant properties of water-borne acrylic pressure sensitive adhesives(PSAs) for automobiles, this study was carried out. Removable PSAs for automobiles were synthesized by emulsion polymerization of monomers, n-butyl acrylate(BA), n-butyl methacrylate(BMA), acrylonitrile(AN), acrylic acid(AA) and 2-hydroxyethyl methacrylate(2-HEMA), and AA and 2-HEMA could act as functional monomers for crosslink. Emulsion polymerization was carried out in a semi-batch type reactor. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, water resistance increased with the amount of BMA, however, the effect of BMA content on the water resistance was insignificant at a range of over 14 wt%. The water resistance also increased with the amount of functional monomers, AA and 2-HEMA. The prepared PSAs satisfied all the standard for automobiles except heat resistance. However, the heat resistance comes nearly up to the standard. Also, acid resistance, alkali resistance and smoke resistance of the prepared PSAs satisfied with the standard.

Normalized Contact Force to Minimize "Electrode-Lead" Resistance in a Nanodevice

  • Lee, Seung-Hoon;Bae, Jun;Lee, Seung Woo;Jang, Jae-Won
    • Bulletin of the Korean Chemical Society
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    • v.35 no.8
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    • pp.2415-2418
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    • 2014
  • In this report, the contact resistance between "electrode" and "lead" is investigated for reasonable measurements of samples' resistance in a polypyrrole (PPy) nanowire device. The sample's resistance, including "electrode-lead" contact resistance, shows a decrease as force applied to the interface increases. Moreover, the sample's resistance becomes reasonably similar to, or lower than, values calculated by resistivity of PPy reported in previous studies. The decrease of electrode-lead contact resistance by increasing the applying force was analyzed by using Holm theory: the general equation of relation between contact resistance ($R_H$) of two-metal thin films and contact force ($R_H{\propto}1/\sqrt{F}$). The present investigation can guide a reliable way to minimize electrode-lead contact resistance for reasonable characterization of nanomaterials in a microelectrode device; 80% of the maximum applying force to the junction without deformation of the apparatus shows reasonable values without experimental error.

Effects of the Polarization Resistance on Cyclic Voltammograms for an Electrochemical-Chemical Reaction

  • Chang, Byoung-Yong
    • Journal of Electrochemical Science and Technology
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    • v.6 no.4
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    • pp.146-151
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    • 2015
  • Here I report an electrochemical simulation work that compares voltammetric current and resistance of a complex electrochemical reaction over a potential scan. For this work, the finite element method is employed which are frequently used for voltammetry but rarely for impedance spectroscopy. Specifically, this method is used for simulation of a complex reaction where a heterogeneous faradaic reaction is followed by a homogeneous chemical reaction. By tracing the current and its polarization resistance, I learn that their relationship can be explained in terms of rate constants of charge transfer and chemical change. An unexpected observation is that even though the resistance is increased by the rate of the following chemical reaction, the current can be increased due to the potential shift of the resistance made by the proceeding faradaic reaction. This report envisions a possibility of the FEM-based resistance simulation to be applied to understand a complex electrochemical reaction. Until now, resistance simulations are mostly based on equivalent circuits or complete mathematical equations and have limitations to find proper models. However, this method is based on the first-principles, and is expected to be complementary to the other simulation methods.

A Study on Composites of Ethylene-Vinyl Acetate Copolymer and Ethylene-Propylene-Diene Rubber with Aluminum Hydroxide as a Fire Retardant

  • Lee, Yu Jun;Lee, Su Bin;Jung, Jae Young;Lee, Dam Hee;Cho, Ur Ryong
    • Elastomers and Composites
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    • v.51 no.2
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    • pp.93-98
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    • 2016
  • The composites of EVA/EPDM including aluminum trioxide (ATH) as a fire retardant were manufactured for the purpose of improving low temperature property and flame resistance in the rubbery materials. The ratio of EVA to EPDM didn't affect the flame resistance of the rubber composites. The addition of ATH resulted in increase of the flame resistance. In the evaluation of the cold resistance, the increasing EPDM content showed enhancement of cold resistance in the composites due to increasing low Tg EPDM. It was found out that tensile strengths of the composites showed a maximum value at 100 phr of ATH by reinforcing effect, but a minimum value at 200 phr of ATH owing to slippage between the flame retardant by the external stress. In the measurement of solvent resistance in tetrahydrofuran, the increasing ATH content yielded enhancement of solvent resistance by reducing swelling of the composite, and increasing EPDM content also resulted from increase of the solvent resistance by reduction of polarizability as well as increase of crosslink in the composites.

An Experimental Study on the Chemical Resistance of Concrete(II) -The case of mortar with silica sand particle- (콘크리트의 내화학성에 관한 실험적 연구(II)-규사 분말을 치환한 모르터의 경우-)

  • 윤보현;김제원;설광욱;김명재;부척량
    • Magazine of the Korea Concrete Institute
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    • v.9 no.1
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    • pp.153-163
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    • 1997
  • This paper is an experimental study of the chemical resistance of mortar which contains silica sand particles. The possible use of silica sand particles in the future as an admixture for improving chemical resistance of mortar is examined in mortar model experiments. The possibility of using mortar model its prediction models for the chemical resistance of concrete is examined. The results obtained are as follows. Since the experimental results from the chemical resistance tests based on the kinds and the amount of replaced admixture are similar to those from the concrete. mortar model could be used as a prediction model of chemical resistance of concrete.

Preparation and Resistant Property of Acrylic Adhesives for Automobiles Protection (자동차 보호용 아크릴 점착제의 제조 및 내성조사)

  • Hahm, Hyun-Sik;Park, Ji-Young;Ahn, Sung-Hwan;Kim, Song-Hyoung;Hong, Suk-Young;Park, Hong-Soo
    • 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.

Consideration of Geosynthetics Chemical Resistance Test for Long-Term Performance Evaluation (장기성능 평가를 위한 토목섬유 화학저항성 시험 고찰)

  • Jeon, Han-Yong;Jang, Yeon-Soo;Gong, Hak-Bong
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.222-232
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    • 2009
  • In this study, the real site test conditions were considered and applied to suggest the improved test method for geosynthetics chemical resistance. For this, index and performance tests were done to specify and regulate the more approached test method. Accelerated model by Arrhenius equation was applied to interpretate the experimental data. Through analysis and comparison the overall experimental results, we could suggest the possibility and setup the advanced chemical resistance test method for geosynthetics.

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Establishment of Doxorubicin-resistant Subline Derived from HCT15 Human Colorectal Cancer Cells

  • Choi, Sang-Un;Kim, Nam-Young;Choi, Eun-Jung;Kim, Kwang-Hee;Lee, Chong-Ock
    • Archives of Pharmacal Research
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    • v.19 no.5
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    • pp.342-347
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    • 1996
  • Doxorubicin, one of the clinically most useful anticancer agents, is used alone or in combination with other drugs against a wide variety of tumors, recently. But cancer cells developed resistance to this agent in many ways. This resistance is an important limiting factor of doxorubicin for anticancer drug. We newly established doxorubicin-resistant HCT15/CL02 subline from parental HCT15 human adenocarcinoma colon cancer cells. HCT15/CL02 revealed resistance to doxorubicin about 85-fold of its parental cells, and it also revealed cross-resistance to actinomycin D, etoposide and vinblastine but not to displatin and tamoxifen. And verapamil, a reversal agent of multidrug-resistance (MDR) by P-glycoprotein, elevated the cytotoxicity of doxorubicin against both HCT15 and GCT15/CL02 cells. But the relative resistant rate was not reduced. Verapamil had no effects on the tosicity of cisplatin to the both cell lines. These results indicate that HCT15/CL02 cells have some functionally complex mechanisms for MDR.

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Study on Properties and Accelerated Life-time Test of Rubber O-ring by Temperature Stress

  • Shin, Young-Ju;Kang, Bong-Sung;Chung, Yu-Kyung;Choi, Kil-Yeong;Shin, Sei-Moon
    • Proceedings of the Korean Reliability Society Conference
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    • pp.48-54
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    • 2006
  • In this thesis, accelerated life test (ALT) method and procedure for rubber O-ring are applied to assure specified reliability of the products at guaranteeing the life of the products. Rubber O-ring is parts that keep intensity or make machine operation smoothly on attrition portion of machine and is used to prevent that oil is leaked. Usually. Rubber O-ring used NBR that is copolymer of acrylonitrile and butadiene. this are superior oil resistance, heat resistance, durability of abrasion, cold resistance, chemical resistance etc. The accelerated life test model for rubber O-ring are developed using the relationship between stresses and life characteristics of products. Using the accelerated life test method and the acceleration life test equipment which is developed, we performed life test, collected life data and analyzed the results of tests. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably.

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