• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.235-238
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• 2005

Sulfonated poly(ether sulfone) copolymers (PESs) were synthesized using hydroquinone 2-potassium sulfonate (HPS) with other monomers (bisphenol A and 4-fluorophenyl sulfone). PESs with different $mole\%$ of hydrophilic group were prepared by changing the mole ratio of HPS in the polymerization reaction. The chemical structure and the thermal stability of these polymers were characterized by using $^1H-NMR$, FT-IR and TGA techniques. The PES 60 membrane, which has $60 mole\%$ of HPS unit in the polymer backbone, has a proton conductivity of 0.091 S/cm and good insolubility in boiling water. The TGA showed that PES 60 was stable up to $272^{\circ}C$ with a char yield of about $29\%\;at\;900^{\circ}C\;under\;N_2$ atmosphere. To investigate the single cell performance, the catalyst coated PES 60 membrane was used and a single cell test was carried out using $H_2/O_2$ gases as fuel and oxidant at various temperatures. We observed that the cell performance was enhanced by increasing the cell temperature. A current density of $1400 mA/cm^2$ at 0.60 V was obtained at $70^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.284-292
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• 1977

Epoxy-methacrylate prepolymer was synthesized from methacrylic acid and a diglycidyl ether type low molecular weight epoxy resin, and the electron beam curing of the prepolymer was studied using styrene and polyethyleneglycol dimethacrylates as comonomers. The esterification was carried out quantitatively without any side reaction adding more than 250∼300ppm hydroquinone and less than $1{\%}$ (wt) triethanolamine by wt. of methacrylate acid, respectively. In the radiation curing under air atmosphere, the maximum gel fraction was observed at 10∼$30{\%}$ monomer contents. The rate of gel formation was decreased by the presence of unreacted epoxy group and acid in the prepolymer and increased with increasing degree of polymerization of polyethyleneglycol block in the dimethacrylates. Considerable oxygen effect in the curing, particularly when polyethyleneglycol dimethacrylate was used as a comonomer, was recognized through the differences of the product properties, though no remarkable differences were found in the rate of gel formation in air and nitrogen atmosphere.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.517-523
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• 1994

The effects of cure kinetics and mechanism of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline) with SN(succinonitrile) and HQ(hydroquinone) as an additive and accelerator were investigated. Cure kinetics was evaluated by Kissinger equation and fractional-life method through DSC analysis. The activation energy has hydroxyl group as an accelerator, the activation energy and the starting cure-temperature were lower than those of DGEBA/MDA/SN system. Cure mechanism of those systems was investigated through FT-IR according to the various SN contents. The ratio was SN : HQ = 4 : 1. It has been known that the cure reactions of an epoxy-diamine system are composed of primary amine-epoxy reaction, secondary amino-epoxy reaction and epoxy-hydroxyl group reaction. But in DGEBA/MDA/SN system, primary amino-CN group reaction and CN group-hydroxyl group reaction were added to the above mentioned reactions. These reactions attributed to the long main chain and the low crossliking density. And in DGEBA/MDA/SN/HQ system, hydroxyl group of HQ formed a transition state with epoxide group and amime group and also opened the ring of the epoxide group rapidly, then amino-epoxy reaction took place easily.

• Applied Biological Chemistry
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• v.17 no.3
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• pp.149-176
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• 1974

Eight substituted diphenyl ether herbicides and some of their photoproducts were studied in terms of solution phase photolysis under simulated environmental conditions by using a Rayonet photochemical reactor. The test compounds absorbed sufficient light energy at the wavelength of 300 nm to undergo various photoreactions. All the photoproducts were confirmed by means of tlc, glc, ir, ms, and/or nmr spectrometry. The results obtained are summarized as follows: Solution phase photolysis of C-6989: An exceedingly large amount of p-nitrophenol formed strongly indicates the readiness of the ether linkage cleavage of this compound as the main reaction in all solvents used. Photoreduction of nitro to amino group(s) and photooxidation of trifluoromethyl to carboxyl group were recognized as minor reactions. Aqueous photolysis of p-nitrophenol: Quinone(0.28%), hydroquinone (0.66%), and p-aminophenol (0.42%) were confirmed as photoproducts, in addition to a relatively small amount of an unknown compound. The mechanisms of formation of these products were proposed to be the nitro-nitrite rearrangement via $n{\rightarrow}{\pi}^*$ excitation and the photoreduction through hydrogen abstractions by radicals, respectively. Solution phase photolysis of Nitrofen: Photochemical reduction leading to the p-amino derivative was the main reaction in n-hexane. In aqueous solution, the photoreduction of nitro to amino group and hydroxylation predominated over the ether linkage cleavage. Nucleophilic displacement of the nitro group by hydroxide ion and replacement of chlorine substituents by hydroxyl group or, to a lesser extent, hydrogen were also observed as minor reactoins. Solution phase photolysis of MO-338: Photoreduction of the nitro to amino group was marked in the n-hexane solution photolysis. In the aqueous solution, photoreduction of the nitro substituent and hydroxylation were the main reactions with replacement of chlorine substituents by the hydroxyl group and hydrogen, and cleavage of the ether linkage as minor reactions. Photolyses of MC-4379, MC-3761, MC-5127, MC-6063, and MC-7181 in n-hexane and cyclohexane: Photoreduction of the nitro group leading to the corresponding amino derivative and replacement of one of the halogen substituents by hydrogen from the solvent used were the key reactions in each compound. Aqueous photolysis of MC-4379: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, hydroxylation, and replacement of the nitro by hydroxy group were prominent with photoreduction and dechlorination as minor reactions. Aqueous photolysis of MC-3761: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, and photoreduction followed by hydroxylation were the main reactions. Aqueous photolysis of MC-5127: Replacement of carboxyethyl by hydrogen was predominant with ether linkage cleavage, photoreduction, and dechlorination as minor reactions. It was obvious that the decarboxyethylation proceeded more readily than decarboxymethylation occurring in the other compounds. Aqueous photolysis of MC-6063: Cleavage of the ether linkage and photodechlorination were the main reactions. Aqueous photolysis of MC-7181: Replacement of the carboxymethyl group by hydrogen and monodechlorination were the remarkable reactions. Cleavage of the ether linkage and hydroxylation were thought to be the minor reactions. Aqueous photolysis of 3-carboxymethyl-4-nitrophenol: The photo-induced Fries rearrangement common to aromatic esters did not appear to occur in the carboxymethyl group of this type of compound. Conversion of nitro to nitroso group was the main reaction.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.356-361
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• 1996

Cure kinetics of diglycidyl ether of bisphenol A(DGEBA)/4,4'-methylene dianiline(MDA) with hydroquinone-phenyl glycidyl ether(HQ-PGE) as a reactive additive, which was preliminarily synthesized, was investigated by DSC and FT-IR analyses. Kissinger equation and Arrhenius' equation were used to calculate activation energy and pre-exponential factor. When HQ-PGE was added to DGEBA/MDA system, it reduced activation energy of system. When the 5 phr of HQ-PGE was added to DGEBA/MDA system, activation energy was 7.8 kcal/mol by FT-IR analysis and 11.3 kcal/mol by DSC, in comparison with the system without HQ-PGE, activation energy decreased about 30% and 9%, respectively. According to these results, HQ-PGE, introducing agent of this system, acted as a catalyst.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2096-2098
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• 2004

본 논문은 마이크로 유체 소자의 소재로서 많이 쓰이고 있는 poly(dimethyl-siloxane) (PDMS)의 친수성 유지를 위한 표면 개질에 대한 연구이다. PDMS는 유연성, 투명성 등의 다양한 장점을 가지고 있으나, 높은 소수성으로 인하여 유체 소자로의 응용에 제한을 갖는다. 기존 연구에서 수행한 산소 플라즈마 후 2-Hydroxyethyl methacrylate (HEMA) 처리에 의한 PDMS의 표면 개질은 친수성 유지 시간에 한계가 있었다. 이에 친수성 유지 시간을 증가시키기 위하여 경화된 PDMS에 두 시간의 오존 처리 후, 6시간 동안 monomethyl ether hydroquinone (MEHQ)가 제거된 HEMA로 표면을 개질한다. 표면 처리된 PDMS의 친수성 특성을 확인하기 위해 접촉각을 측정하였다. 측정 결과, 오존을 이용하였을 때 $60^{\circ}$ 이하의 낮은 접촉각이 900시간 이상 유지됨을 확인하였다.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.904-909
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• 1994

Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline)/GN(glutaronitrile) system with and without HQ(hydroquinone) as a catalyst was studied by Kissinger equation and Fractional life method. The activation energy of the system with HQ was somewhat lower and the pre-exponential factor of that was higher by about 30% than those of the system without HQ. As 1.25phr of HQ was added, reaction rates increased about 1.8 times.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.606-610
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• 1995

Diglycidyll ether of bisphenol A(DGEBA)/4, 4'-methylene dianiline(MDA)계에 반응성 첨가제 malononitrile(MN)을 첨가하면 내충격성은 크게 향상되나 반응속도는 감소하게 된다. 에폭시 수지의 경화반응은 에폭시기가 개환되어 생성되는 히드록시기가 촉매로 작용하는 자촉매 반응이며, 외부에서도입된 히드록시기도 같은 효과를 나타낸다. 따라서 본 연구에서는 DGEBA/MDA/MN 계의경화 반응속도를 증가시키기 위해 히드록시기를 가진 촉매로서 hydroquinone(HQ)을 도입하였고 이들 계의경화특성 및 열적성질을 고찰하였다. HQ가 첨가됨으로 인해 활성화 에너지는 감속하고 속도상수는 증가하였으며, 발열곡선에서 반응 시작온도가 낮아졌다. 이 결과로부터 HQ가 반응 가속제로 작용하고 있음을 알 수 있다.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.283-290
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• 1988

This study was conducted to clarify the identification of phytotoxic compounds from 5 upland weeds which had been collected at their maturity age in the field of Kyungpook province, Korea. 5 weed species including Stellaria aquatica strongly inhibited the lettuce seed germination. These 5 species were Amaranthus lividus, Stellaria aquatica, Achyranthes japonica, Polygonum perfoliata and Galinsoga ciliata. the degree of inhibitory effects according to various solvent extracts such as ethanol, aceton, chloroform and ether was different as species. In total phenol and diphenol content G. ciliata had largest amount of total phenol with 2.75mg/g, P. perfoliata 1.8mg/g, S. aquatica 1.7mg/g, A. lividus 1.28mg/g, A. japonica 1.27mg/g respectively. A. lividus had much amount of p-cresol, hydroquinone, ferulic, caffeic, p-cl-benzoic and p-coumaric in order. S. aquatica, A. japonica, P. perfoliata and G. ciliata had a large quantity of ferulic, caffeic, 7-OH-coumarin and protocatechuic acids in common. The amount of fatty acids was existed 8.49mg/g in S. aquatica, 7.14mg/g in A. japonica, 7.10mg/g in G. ciliata, 5.49mg/g in P. perfoliata and 4.2mg/g in A. lividus respectively. Most of 4 weeds except G. ciliata had much oxalic acid to the extent of 14-22mg/g. however it appeared that G. ciliata had much quantity of feruic and citric acids.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.737-742
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• 1994

The fracture energy of glass fiber/carbon fiber/epoxy resin hybrid composite system was investigated in the aspect of fracture mechanism. Epoxy resin matrix was DGEBA-MDA-SN-HQ system. On the interface of glass fiber and matrix, post debone friction energy provided a major contribution to the fracture energy, and debonding energy and pull-out energy were of the similar value. In the case of fracture on the interface of carbon fiber and matrix, pull-out energy was the major contributor.