• Composites Research
• /
• 제32권6호
• /
• pp.368-374
• /
• 2019

무기필러가 첨가된 현무암섬유 강화 에폭시 복합재료를 제조하여 그 특성을 평가하였다. 첨가된 무기필러는 각각 수산화마그네슘, 수산화알루미늄, 알루미나, 베마이트이며 이를 첨가제로한 에폭시 수지를 현무암섬유에 핸드레이업으로 함침시킨 후 hot pressing하여 수지 함침량이 30 wt%인 섬유복합재료를 제조하였다. LOI 평가 결과 BFRP의 LOI (28.9)는 에폭시 수지 (21.4)에 비해 향상된 것을 확인하였으며 무기필러가 첨가될 경우 그보다 더욱 향상되는 것을 확인하였다. 또한 무기필러가 첨가된 복합재료는 무기필러가 첨가되지 않은 복합재료에 비해 콘칼로리미터 시험에서 PHRR, THR, TSR 등이 감소하여 무기필러 첨가에 따른 난연 특성 향상을 확인하였다.

• 약학회지
• /
• 제40권6호
• /
• pp.659-665
• /
• 1996

Zinc white is mainly used as a mild astringent, protectant. and has weak antiseptic action. It is well known that the yield of zinc white produced is greatly affected by the syn thetic conditions such as the reactant concentration, reaction temperature, washing water temperature, mole ratio of reactants, and drying temperature, calcination temperature, etc. The purpose of this study is to investigate the optimal synthesis conditions of zinc white produced. A randomized complete block design suggested by G.E.P. Box and K.B. Wilson was applied for this purpose. Basic zinc carbonate was prepared by reacting zinc sulfate and sod. carbonate solution in this study. Zinc white comes when prepared by calcination of basic zinc carbonate. The optimum synthesis conditions of zinc white obtained from this study is as follows: 1) The reacting temperature range is: 92-100$^{\circ}C$, 2) The concentration of reactant solution is 23.6-27%, 3) The optimum mole-ratio: [ZnSO4]/[Na2CO3] is 1.74~1.96, 4) The washing water temperature is 36$^{\circ}C$, 5) The drying temperature range is 68-74$^{\circ}C$, 6) The calcination temperature is 600$^{\circ}C$. The outcome of DSC indicated a desolvation of basic zinc carbonate occurred at about 133.3$^{\circ}C$. The dehydration of the compound ceased at about 267.9$^{\circ}C$ and the decarboxylation ceased at about 379.9$^{\circ}C$. The physical and chemical properties of zinc white as medicine were studied by use of Volume Test.

• 공업화학
• /
• 제5권3호
• /
• pp.431-437
• /
• 1994

에탄을 전화반응 및 MTBE (methyl t-butyl ether)분해반응을 통하여 헤테로폴리산 촉매가 지니는 표면 및 내부 산점의 역할과 형성에 대하여 살펴 보았다. 12-텅스토인산에서 에탄올 탈수반응을 수행할 경우 디에틸에테르는 표면산점에서 생성되며 에틸렌은 촉매 내부산점에서 생성된다. 물은 산점을 강화하는 역할을 하지만 유기염기의 경우 내부 산점을 약화시킨다. 금속염의 산점 형성은 결정수의 가수분해 혹은 금속의 부분적 치환에 따른 양성자에 기인하며 수소로 처리할 경우 산점이 재생되었다. 또한 산 특성 제어를 통하여 선택적 산화반응 촉매로서의 헤테로폴리산 설계가 가능하다.

• 공업화학
• /
• 제20권1호
• /
• pp.40-45
• /
• 2009

본 연구는 유기발광디바이스(OLED)용 적색형광물질인 N-알킬카르바졸-3-비닐렌-2-메틸-4-디시아노메틸렌-4H-피란의 합성에 관한 것으로서 유도체들은 탈수축합, $S_N2$, Vilsmeier, 그리고 Knoevenagel축합반응에 의하여 합성되었다. 이들은 전자공여성의 N-알킬카르바졸-3-비닐렌기와 전자흡인성의 2-메틸-4-디시아노메틸렌-4H-피란의 공액구조를 가지고있다. 합성한 물질은 각각 FT-IR, $^1H-NMR$ 등을 통하여 그의 구조적 특성을 확인하였고, 융점, 수득률을 통하여 열적 안정성, 반응성 등을 확인하였으며, 여기 발광스펙트럼으로부터 이 형광재료들의 광학적 특성을 확인하였다.

• Korean Chemical Engineering Research
• /
• 제44권4호
• /
• pp.369-374
• /
• 2006

$V_2O_5$와 AlMCM-48을 고체상에서 반응시킨 후 소성하면 메조포러스 물질 내에서 V(V) 화학종이 아주 약하게 나타난다. 그러나 환원 과정을 거치면 EPR로 조사할 수 있는 바나딜 $VO^{2+}$ 화학종이 생성된다. $VO^{2+}-AlMCM-48$에 들어있는 바나듐의 화학적 환경을 XRD, EDX, UV-Vis, EPR, $^{29}Si$ and $^{27}Al$ and $^{51}V$ NMR로 조사하였다. 탈수하거나 CO 로 환원하면 바나듐은 MCM-48에 유사 사면체형 $VO^{2+}$ 바나딜 이온 상태로 존재하며 물이 배위되면 찌그러진 팔면체구조로 바뀐다.

• The Plant Pathology Journal
• /
• 제16권3호
• /
• pp.125-129
• /
• 2000

A rapid and efficient assay to determine melanin biosynthesis inhibition of Magnaporthe grisea, a causal agent of the rice blast, by chemicals was developed. Wells in 24-well plates were loaded with spore suspension of the fungus and three known melanin biosynthesis inhibitors of KC10017, tricyclazole, and carpropamid. Subsequent color changes of mycelia and culture media in the wells were observed 7 days after incubation. The wells treated with KC10017 (an inhibitor of polyketide synthesis step and/or pentaketide cyclization step) became colorless, whereas tricyclazole (an inhibitor of 1, 3, 8-trihydroxynaphthalene reductase) or carpropamid (an inhibitor of scytalone dehydratase)-treated wells exhibited red color. They did not show any inhibitory effect on fungal growth. The inhibition of reaction steps prior to 1, 3, 6, 8-tetrahydroxynaphthalene formation was easily determined by colorless medium and mycelia. However, it was impossible to distinguish between inhibition of reduction steps and inhibition of dehydration steps by colors of the cultures. It was accomplished through HPLC analysis of the melanin biosynthesis-involving pentaketide metabolites accumulated by the inhibitors. Through screening of a number of synthetic chemicals using the in vitro assay, we could find a novel chemical group of melanin biosynthesis inhibitor.

• Carbon letters
• /
• 제1권2호
• /
• pp.69-75
• /
• 2000

Naphtha cracking bottom oil was reformed with heat treatment and then spun at $310^{\circ}C$. These pitch-based carbon fibers were carbonized at $1000^{\circ}C$ after oxidation at $280^{\circ}C$, for 90 min. These fibers were chemically activated with molar ratio of KOH/CF (1 : 1) at different temperatures ($250{\sim}900^{\circ}C$) for 1 hr. The process of activation was characterized with DTA, TGA, BET surface area and pore size distribution. The activation of fibers by KOH was performed by several process. One is the reduction process that carbon fiber was reacted with $K_2O$ produced from dehydration process above $400^{\circ}C$. The other is the process that $K_2CO_3$ was directly reacted with carbon fiber. At $800^{\circ}C$, the activation was performed by catalyzed mechanism that $K_2O$ was obtained from the reaction of metal potassium with $CO_2$, then was changed to $K_2CO_3$. At $870^{\circ}C$, the activation was also observed that activation mechanism was promoted by metal catalyst with $CO_2$ from decomposition of $K_2CO_3$. The specific surface area of prepared activated carbon fibers was dependent on the activation mechanism. The specific surface area was in the range of $1519{\sim}2000\;cm^3/g$ and was the largest prepared at $870^{\circ}C$. The pores developed were mostly micropores which was very narrow and uniform. The total pore volume was $0.58{\sim}0.77\;cm^3/g$.

• 대한화학회지
• /
• 제25권2호
• /
• pp.97-102
• /
• 1981

$SiO_2$/$Al_2O_3$ 비가 높은 제올라이트 ZSM-5를 합성하여 메탄올의 탄화수소로의 전환반응을 조사하였다. 메탄올이 전환되어 올레핀, 파라핀, 시클로파라핀 및 방향족화합물이 생성되었으며 특히 방향족 화합물에 대한 큰 선택성을 보여 주었고 1,3,5-trimethylbenzene의 크기정도에 제한된 형상선택성 촉매작용임을 알 수 있었다. 수소형태(HZSM-5)가 활성이 커, 메탄올이 탈수되어 일어나는 잇단 복잡한 반응들이 산촉매반응이 주임을 보여 주었다. ZSM-5와 구조가 유사한 mordenite와 3차원구조를 지닌 faujasite 촉매에서의 메탄올의 반응으로 구조적 영향과 TPD실험에 의한 산점분포를 비교한 결과 메탄올로부터 방향족화합물에 이르기까지의 탄화수소 합성에서의 ZSM-5 제올라이트의 촉매작용은 높은 실리카함량에 기인한 강한 산성과 교차하는 세공관 구조에 의한 분자체 효과에 의한 것으로 볼 수 있다.

• 청정기술
• /
• 제21권1호
• /
• pp.62-67
• /
• 2015

본 연구에서는 그래핀과 다중벽 탄소나노튜브를 포함하는 하이브리드 소재의 제조 및 슈퍼캐패시터 전극물질로의 활용에 관한 내용이 진행되었다. 이를 위하여 산화그래핀과 아민(-NH₂) 그룹이 치환된 다중벽 탄소나노튜브를 산 촉매 하에서 반응시켜, 새로운 이민(-C=N-) 결합이 도입된 하이브리드 복합체를 합성하였다. 상기 제조된 하이브리드 소재를 슈퍼캐패시터 전극 물질로 사용하고자 수산화칼륨 전해질 기반의 3상 전극 시스템을 활용하여 전기화학적 특성을 살펴보았다. 또한 하이브리드 소재에 존재하는 그래핀과 다중벽 탄소나노튜브의 비율 변화 실험을 통하여, 그래핀/탄소나노튜브의 질량비가 7.5/1일 때 그 특성이 최적화가 됨을 알 수 있었다. 최적화된 전극은 높은 비축천용량(132 F/g)을 나타내었을 뿐만 아니라, 반복된 충방전 실험에서 높은 안정성(95%, retention after 5000 cycles)을 나타내었다.

• Bulletin of the Korean Chemical Society
• /
• 제15권11호
• /
• pp.940-944
• /
• 1994

The crystal structure of an ethylene sorption complex of dehydrated $Ag_{12}-A $reacted with bromine vapor has determined by single-crystal X-ray diffraction techniques in the cubic space group of Pm3m at 22(l)$^{\circ}$C (a=12.180(2) ${\AA}$). The crystal was prepared by dehydration of $Ag_{12}$-A at 400 $^{\circ}$C and $2 {\times} l0^{-6}$ Torr for 2 days, followed by exposure to 200 Torr of ethylene gas at 24(l) $^{\circ}$C for 1 hr. After the ethylene gas was evacuated for 1 hr, the crystal was exposed to 180 Torr of bromine vapor at 24(l) $^{\circ}$C for 1.5 h. The structure was refined to the final error indices, $R_1=0.066\;and\;R_2$ (weighted)=0.055, using 137 independent reflections for which I>3${\sigma}$I. About 55% of the sodalite unit contain two 6-ring $Ag^+$ ions and the remaining 45% contain $Ag_6$ molecules complexed to 2 $Ag^+$ ions at 6-ring sites to give $(Ag^+)_2(Ag_6).$ Upon sorption of ethylene, 4.75 ethylene molecules were sorbed per unit cell and of these, only 1.25 ethylene molecules were brominated by treatment of dibromine because of the limitation of the available space for the reaction products in the large cavity. In the large cavity, each of 3.5 $Ag^+$ ions forms a lateral ${\pi}$ complex with an ethylene molecule. About 2.5 8-ring $Ag^+$ ions per unit cell interact with 1.25 1,2-dibromoethane and each of ca. 1.25 6-ring $Ag^+$ ions also interacts with one of bromine atoms of 1,2-dibromoethane. Each bromine atom approaches a carbon atom with C-Br(l)=2.07(20) ${\AA}$ and C-Br(2)=2.07(10) ${\AA}$, respectively.