• Korean Journal of Materials Research
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• v.3 no.3
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• pp.237-244
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• 1993

The characteristics of composite polymer electrolytes obtained by adding a fine ceramic powder($\gamma-{LiAlO}_{2}$) with a diameter of $1{\mu}$m to a poly(ethylene oxide)/lithium trifluoromethane sulfonate (LiC$F_3$S$O_3$) complex are described in terms of morphological and mechanical behavior. The addition of uniformly dispersed ceramic powder greatly improves the electrical and mechanical properties of solid polymer electrolytes at ambient temperature. For the composite polymer electrolytes under this study, the optimum composition of the $\gamma-{LiAIO}_{2}$ in the composite for maximum ionic conductivity was found to be 20 wt%.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.329-331
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• 2006

연료전지용으로 많이 사용되는 전불소계 고분자인 Nafion은 좋은 기계적, 화학적 안정성 및 높은 이온전도도에도 불구하고 고가의 생산단가, 높은 메탄올 투과도, 그리고 MEA 재활용 문제 등으로 인해 상업적 응용에 제한이 있다. 본 연구는 불소그룹을 함유한 술폰화된 아릴렌이서계 블록 공중합체 고분자 전해질막의 제조 및 연료전지 특성에 관한 것이다. 이러한 고분자를 제조하기 위하여 양말단에 불소계 비닐기를 가지면서, 상온에서 술폰화 가능한 biphenyl계 단량체와 술폰화가 불가능한 sulfonyl계 단량체를 각각 합성하였으며, 이들로부터 다양한 몰조성과 분자량을 갖는 올리고머를 포함한 일련의 perfluorocyclobutane기를 포함하는 블록 공중합체를 열적 고리화 부가중합을 사용하여 합성하였다. 제조된 블록 공중합체를 상온에서 술폰화제인 chlorosulfonic acid를 이용하여 선택적으로 후술폰화시켜 강산 이온기인 sulfonic acid를 블록 올리고머에 도입하였다. 합성된 고분자들의 연료전지 특성을 Nafion-115와 비교하였다. 술폰화가 되는 올리고머 블록의 비율 증가에 따라 이온교환능력이 증가하였고, 그에 따라 높은 함수율과 이온 전도도를 나타내었으며 건조 및 습윤 상태에서도 기계적 강도가 우수하였다. 최적화된 블록공중합체를 대상으로 MEA를 제조하여 연료전지 초기성능을 측정한 결과 Nafion과 유사한 전기화학적 성능을 나타내었다.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.46-55
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• 2006

본 연구는 불소그룹을 함유한 술폰화된 아릴렌에테르계 블록 공중합체 고분자 전해질막의 제조 및 연료전지 특성에 관한 것이다. 이러한 불소그룹을 함유한 술폰화된 아랄렌에테르계 블록 공중합체를 제조하기 위하여 양말단에 불소계 비닐기를 가지면서, 고분자 전환시 상온에서 술폰화 가능한 biphenyl계 단량체와 술폰화가 불가능한 sulfonyl계 단량체를 각각 합성하였다. Biphenyl계 단량체로 부터 올리고머를 합성한 후 sulfonyl계 단량체와 열적 고리화 부가중합을 하여 다양한 몰조성을 갖는 일련의 perfluorocyclobutane(PFCB)기를 포함하는 블록 공중합체를 제조하였다. 제조된 블록 공중합체를 상온에서 술폰화제인 chlorosulfonic acid(CSA)를 이용하여 후술폰화시켜 강산 이온기인 sulfonic acid를 biphenyl계 올리고머 부분에 선택적으로 도입하였다. 이렇게 제조된 술폰화된 고분자를 제막한 후 연료전지 특성을 Nafion-115와 비교하였다. 술폰화가 되는 올리고머 블록의 비율 증가에 따라 이온교환능력 (IEC)이 증가하였고 , 그에 따른 팽윤도 역시 증가하는 것을 보였다. 술폰화된 고분자들은 건조 및 습윤 상태에서도 기계적 강도가 우수하였다. 최적화된 술폰화 블록 고분자(S-2) 를 대상으로 membrane electrolyte assembly(MEA) 를 제조하여 연료전지 초기성능을 측정한 결과 Nafion-112와 유사한 전기화학적 성능을 나타내었다.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.654-661
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• 2013

The current research is designed to analyze sterilization effects on mulberries in terms of storage temperature and storage period after treating with tap water (TW), electrolyzed water (EW) and aqueous chlorine dioxide ($ClO_2$). The treated $ClO_2$ concentrations are 10, 50, 100 and 200 ppm. In each concentration, the mulberries are soaked for 30 seconds respectively. The sterilization effects are being compared at room temperature ($25^{\circ}C$) and at $4^{\circ}C$, respectively. And the enzyme activity related to quality is also being investigated and analyzed about for browning inhibition effects. Microbial sterilizing power increases more in treating plots with EW and $ClO_2$ than treating plot with TW. Futhermore sterilizing power of $ClO_2$ increased sharply on high concentration treatment plot as well. Sterilization effects of $ClO_2$ during storage time are better at cold temperature. Pictures taken from scanning electron microscope reveal that there are no microbes in sterilizing solutions treatment plots. From measurement of the enzyme activity, it is concluded that activities decrease more in sterilizing solutions treatment plots as comparing with TW treated plot during the time. The amount of total polyphenolics decrease with the time passing and EW and $ClO_2$ treatment shows less contents than TW treatment. Thus, EW and $ClO_2$ treatment of mulberris are considered as method to improve safety by reducing total plate count and to contribute to quality maintenance and to extend storage time.

• Polymer(Korea)
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• v.32 no.1
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• pp.85-89
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• 2008

Acrylate polymer gel electrolytes containing N-methoxymethyl-N-methylpyrrolidium bis (trifluoro - methansulfonyl) imide (MPSI) as an ionic liquid were synthesized by solution polymerization in the presence of carbonate solvent. ionic conductivity and mechanical properties of the polymer gel electrolytes were investigated by impedance analyzer and universal testing machine as a function of the amount of polymer, and ionic liquid and type of crosslinker. The maximum ionic conductivity of polymer gel electrolytes was 0.8 mS/cm at $25^{\circ}C$ with 15 wt% of polymer, 30 wt% of ionic liquid and 5 wt% of crosslinker. The mechanical analysis showed that the tensile strength of polymer gel electrolytes increased with additional polymer contents and had the maximum value of 0.5 MPa with a reasonable ionic conductivity.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.65-70
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• 2014

In this study, crosslinked poly(POEM-co-AMPSLi-co-GMA)s were prepared by epoxy coupling of GMA after radical copolymerization of AMPS, POEM and GMA followed by acid-base titration reaction between sulfonic acid of AMPS and $Li_2CO_3$. It was observed that the crystalline melting temperature of POEM was effected by mol% of components and shifted to lower value by lithiation of AMPS group. The ionic conductivity of crosslinked polymer electrolyte was decreased by addition of GMA but maintained over $1.0{\times}10^{-6}S\;cm^{-1}$ until 16 mol%. Particularly, the self-doped polymer electrolyte with 2 mol% of GMA showed its ionic conductivity as high as $4.08{\times}10^{-6}S\;cm^{-1}$ at room temperature and electrochemical stability up to 6 V. In addition, 0.11 MPa of modulus and 270% of elongation were obtained from the free standing film of crosslinked polymer electrolyte.

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.51-57
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• 2015

We report the effect of the impurities including water and bromide in the propylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMPyr-TFSI) on the electrochemical performance of lithium ion batteries. The several kinds of PMPyr-TFSI electrolytes with different amount of impurities are applied as the electrolyte to the cell with the high potential electrode, $LiNi_{0.5}Mn_{1.5}O_4$ spinel. It is found that the impurities in the electrolytes cause the detrimental effect on the cell performance by tracing the cycleability, voltage profile and Coulombic efficiency. Especially, the polarization and Coulombic efficiency go to worse by both impurities of water and bromide, but the cycleability was not highly influenced by bromide impurity unlike the water impurity.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.433-442
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• 1996

Electrochemical characteristics and physical properties of polymer electrolyte which immobilized lithium salts such as $LiClO_4$ and $LiCF_3SO_3$ and plasticizers such as ethylene carbonate(EC) and propylene carbonate(PC) in high molecular weight poly(ethylene oxide)[PEO] polymer was investigated. PEO-Li based polymer electrolyte with plasticizers showed ionic conductivity of $10^{-4}S/cm$ at room temperature and high electrochemical stability up to 4.5 V(vs. $Li^+/Li$), so it can be applied to lithium secondary battery. The crystallinity of PEO decreased with the addition of lithium salts and plasticizers, especially $LiClO_4$ and PC showed more effective than and $LiCF_3SO_3$ and EC. Glass transition temperature($T_g$) of polymer electrolyte increased with increasing lithium salt concentration whereas melting temperature ($T_m$) decreased. Polymer electrolyte with plasticizers crystallized at $6^{\circ}C$.

• Journal of the Korean Electrochemical Society
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• v.7 no.2
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• pp.89-93
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• 2004

Sulfonated polysulfone (SPSF) with poly(phenylmethyl silsesquioxane, PPSQ) composite polymer electrolyte membranes were prepared and their proton conductivity, water uptake and methanol permeability of membranes were characterized. By controlling the ratio of $(CH_3)_3SCI\;and\;CISO_3H$ and reaction time, SPSF with $37\~75\%$ degree of sulfonation were synthesized. The increase of sulfonate groups in the base polymer resulted in the increase of the water uptake in the membranes as well as methanol permeability. Composite membranes were prepared by casting of DMF solution of SPSF and PPSQ. The proton conductivity of the composite membrane at room temperature was $2.8\times10^{-3}\~4.9\times10^{-2}S/cm.$ The increase of PPSQ contents in composite membranes resulted in a decrease in water uptake and methanol permeability. Composite membranes containing $5\%$ PPSQ did not make a significant effect on the proton conductivity nO methanol permeability compared with that of pristine SPSF, but a significant decrease of water uptake was observed.

• Korean Journal of Materials Research
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• v.6 no.9
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• pp.885-899
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• 1996

초강인 AISI 4340강을 85$0^{\circ}C$에서 2시간 동안 오스테나이징 처리 후 수냉하고, 250, 400, $600^{\circ}C$에서 각각 2시간 동안 템퍼링 처리를 하였다. AISI 4340강의 인장 특성은 상온에서 측정되었다. AISI 4340강 위에 니켈 전해도금된 것과 도금되지 않은 시편의 분극 특성이 3.5wt%NaCI 수용액과 인공해수에서 측정되었다. AISI 4340강위에 니켈 전해도금된 시편은 500mV(vs. Ag/AgCI)이하의 전위에서 부식 저항이 크게 향상되었다. 그러나 1A/$\textrm{cm}^2$의 전류밀도에서 30분 이상 니켈 전해도금된 시편은 도금층에 불순물과 기공이 형성되었기 때문에 AISI 4340강의 부식 저항은 감소되었다. AISI 4340강의 수소취화형 응력부식균열을 여러 작용 응력과 음극인가전력에서 U-bend 시편을 이용하여 IN 3.5 wt% NaCI 수용액에서 조사되었고, 수소취화형 응력부식균열 거동은 주사전자현미경으로 조사되었다.