• 공업화학
• /
• 제25권4호
• /
• pp.418-424
• /
• 2014

본 연구에서는 NaCl/$H_3PO_4$ 혼합수용액을 사용하여 라이오셀 섬유의 내염화 처리를 수행하고 이에 따른 열 안정성과 내산화성의 향상 효과를 고찰하였다. 라이오셀 섬유를 다양한 공정조건으로 내염화 처리한 후 열 안정성과 내산화성을 측정 및 분석하고 그에 따른 메커니즘을 제시하였다. 실험결과, 내염화 처리된 라이오셀 섬유의 적분 열분해 온도(integral procedural decomposition temperature, IPDT)와 한계산소지수(limited oxygen index, LOI)는 약 23, 30% 증가하였으며, 활성화 에너지(activation energy, $E_a$) 값은 약 24% 향상된 것을 알 수 있었다. 이러한 결과는 $H_3PO_4$와 NaCl가 연소시 에스테르화 반응, 탈수소화 반응 및 C-C결합의 분해반응으로 char 형성을 촉진하고 섬유 표면에 형성된 탄소 층을 형성함으로써, 고분자 수지 내부로 산소와 열 공급을 물리적으로 차단하여 열 안정성과 내산화성이 향상된 것으로 판단된다. 이러한 결과를 바탕으로, NaCl/$H_3PO_4$ 혼합수용액을 이용한 내염화 처리 공정의 최적화된 인자 및 메커니즘을 제시하였고 열 안정성과 내산화성이 향상된 라이오셀을 성공적으로 제조하였다.

• 한국화재소방학회논문지
• /
• 제29권2호
• /
• pp.25-32
• /
• 2015

라이오셀 섬유의 열 안정성과 내산화성을 향상시키기 위하여 $Na_3PO_4$ 수용액으로 내염화 처리를 실시하였다. 다양한 공정조건으로 라이오셀 섬유를 내염화 처리한 후 열 안정성과 내산화성을 측정 및 분석하고 그에 따른 메커니즘을 고찰하였다. 내염화 처리된 라이오셀 섬유의 적분 열분해 온도(integral procedural decomposition temperature, IPDT)와 활성화 에너지(activation energy, $E_a$)값은 각각 약 30, 160%로 향상된 것을 알 수 있었다. 이는 $Na_3PO_4$가 연소 시 에스테르화 반응, 탈수소화 반응 및 C-C 결합의 분해반응으로 char 형성을 촉진하여 섬유 표면에 보호층을 형성하여, 고분자 수지 내부로 산소와 열 공급을 물리적으로 차단하여 열 안정성과 내산화성이 향상된 것으로 판단된다. 이러한 결과를 바탕으로, $Na_3PO_4$ 수용액을 이용하여 열 안정성과 내산화성이 향상된 라이오셀을 제조하였고, 내염화 처리공정의 최적화된 인자 및 메커니즘을 고찰하였다.

• Bulletin of the Korean Chemical Society
• /
• 제33권9호
• /
• pp.2999-3003
• /
• 2012

Various types of room temperature ionic liquids (RTILs) containing 1,1-dicyano-1-acetylmethanide anion ($[C(CN)_2(COCH_3)]^-$, $[DCNAcC]^-$) were prepared and their physical and electrochemical properties were studied. All of these ILs exhibited high thermal stabilities over $200^{\circ}C$ and relatively high ionic conductivities up to 29.4 $mS\;cm^{-1}$ at $80^{\circ}C$. Although the ionic conductivity of IL containing bis(trifluoromethanesulfonyl)-imide ($[Tf_2N]^-$) anion is higher than that of ILs bearing $[DCNAcC]^-$ anion, the specific capacitance of ILs bearing $[DCNAcC]^-$ anion are higher than that of IL containing $[Tf_2N]^-$ anion and showed high temperature dependence. Such favorable electrochemical properties of these ILs are likely to be attributed to the efficient dissociation of cation and anion at higher temperature and enhanced electrosorption of $[DCNAcC]^-$ anion at the electrode.

• 한국연소학회지
• /
• 제20권3호
• /
• pp.8-12
• /
• 2015

The CO reduction characteristics of hot air stream diluted with exhaust gas in a perfectly stirred reactor (PSR) were investigated numerically. The dilution ratio ($\Omega$), inlet temperature ($T_{in}$), and residence time ($\tau$) were considered as parameters to investigate the effects of those on the emission indices for CO and $CO_2$ (EICO and $EICO_2$). The roles of dominant reactions and the production rates of major species were analyzed. It was found from the EICO trend that the supplied CO in the air stream was consumed. The EICO increased negatively with $T_{in}$ at fixed $\tau$ regardless of $\Omega$. However, the magnitude of EICO and minimum inlet temperature for CO reduction showed complicated trend according to the variation of $\tau$. It was identified that the OH radical, generated from the reactions, $O_2+H{\leftrightarrow}O+OH$ and $2OH{\leftrightarrow}H+H_2O$, affected the CO reduction by the reaction, $CO+OH{\leftrightarrow}H+CO_2$. However, the CO emission ratio increased at sufficiently high inlet temperature range due to the thermal dissociation of $CO_2$.

• 한국세라믹학회지
• /
• 제43권1호
• /
• pp.48-54
• /
• 2006

Hydroxyapatite $(HAp,\;Ca_{10}(PO_4)_6(OH)_2)$/alumina composites were fabricated with the addition of fluorides, such as $MgF_2$ and $CaF_2$. In this study, the effect of fluorides on the inhibition of phase decomposition and the mechanical properties of HAp was investigated. Due to the higher solubility of F ion in HAp structure, $MgF_2$ additive was more effective compared to $CaF_2$ additive in the lowering decomposition temperature of HAp. Therefore, the dissociation tendency of HAp was fully inhibited below $1400^{\circ}C$. The mechanical properties of HAp composites with $MgF_2$ additive showed higher value (flexural strength: $\~170MPa$, Vickers hardness: $\~7\;GPa$, fracture toughness: $\~1.5\;MPam^{1/2}$) compared to $MgF_2-free$ composites. The linear thermal expansion coefficient of HAp composites with $MgF_2$ showed the value of $16.4\times10^{-6}/^{\circ}C\;at\;20\~400^{\circ}C $.

• 한국세라믹학회지
• /
• 제22권5호
• /
• pp.71-75
• /
• 1985

This study deals with sintering and corrosive behavior of sintered zircons mixed with 5wt% of clay $Cr_2O_3$ $CrO_3-MgO$ aqueous solution and $CrO_3-Mg(OH)_2$ aqueous solution. Measurements were conducted by firing specimens at 135$0^{\circ}C$ 145$0^{\circ}C$ and 155$0^{\circ}C$ 1$650^{\circ}C$ for 3hrs in oxidized and reduced atmospheric conditions. Following results were obtained. 1. Sintered zircon with 5 wt% clay showed that highest compressive strength and the lowest apparent porosity and the other showed less positive result than above specimen in order of zircon with $CrO_3-MgO$ aqueous solution $CrO_3-Mg(OH)_2$ aqueous solution and $Cr_2O_3$. 2. The more firing temperature increased the more its strength improved and porosity decreased and specimen which was fired over 155$0^{\circ}C$ and in reduced atmospheric condition showed better results. 3. Zircon with additives which was fired over 155$0^{\circ}C$ showed the evidence of thermal dissociation but it was not rebonded completely during cooling. 4. Zircon with $CrO_3-MgO$ aqueous solution and $CrO_3-Mg(OH)_2$ aqueous solutiion showed more corrosive resistance than zircon itself and zircon-clay system.

• 한국자동차공학회논문집
• /
• 제15권3호
• /
• pp.166-173
• /
• 2007

A numerical study was conducted to have the effect of $CO_2$ addition to fuel on the chemical reaction mechanism with the change of the initial concentration of $CO_2$ and the axial velocity gradient. From this study, it was found that there were two serious effects of $CO_2$ addition on a non-premixed flame ; a diluent effect by the reactive species reduction and chemical effect of the breakdown of $CO_2$ by the third-body collision and thermal dissociation. Especially, the chemical effect was serious at the lower velocity gradient of the axial flow. It was certain that the mole fraction profile of $CO_2$ was deflected and CO was increased with the initial concentration of $CO_2$. It was also ascertained that the breakdown of $CO_2$ would cause the increasing of CO mole fraction at the reaction region. It was also found that the addition of $CO_2$ did not alter the basic skeleton of $H_2-O_2$ reaction mechanism, but contributed to the formation and destruction of hydrocarbon products such as HCO. The conversion of CO was also suppressed and $CO_2$ played a role of a dilution in the reaction zone at the higher axial velocity gradient.

• 전기화학회지
• /
• 제13권3호
• /
• pp.198-202
• /
• 2010

Lithium co-polyelectrolyte-ionic liquid systems, using poly (lithium 2-acrylamido-2-methyl propanesulfonate; PAMPSLi) and polyvinyl formamid (PVF) were prepared and their electrochemical and physical properties were measured. The conductivity of co-polymer systems, PAMPSLi/PVF/N, N-dimethyl-N-propyl-N-butylammonium tricyanomethanide (PAMPSLi/PVF/$N_{1134}$TCM) and PAMPSLi/PVF/N, N-dimethyl-N-propyl-N-butylammonium dicyanamide (PAMPSLi/PVF/$N_{1134}$DCA) exhibited low viscosity ($N_{1134}$TCM:$N_{1134}$DCA 28.6cP, 28.7cP) and higher conductivity ($2.48{\times}10^{-3}Scm^{-1}$, $2.2{\times}10^{-3}Scm^{-1}$) than homopolymer system. The ionic conductivity PAMPSLi/PVF/1-ethyl-3-methyl imidazolium dicyanamide (PAMPSLi/PVF/emImDCA) exhibited $1.54{\times}10^{-3}Scm^{-1}$ and low viscosity (emImDCA: 28.09cP). High flexibility of imidazolium cation and dissociation of lithium cation from the co-polymer chains were affected by high conductivity and low viscosity.

• 대한화학회지
• /
• 제46권2호
• /
• pp.99-116
• /
• 2002

Thiazolylazo 화합물과 barbituric산, uracil, thiouracil, citrazinic산 chromotrotropic산, gallict산, pyrogallol 그리고 salicylic산의 Co(II), Ni(II) 그리고 Cu(II) 착화합물의 제조하였고, $^1H$ NMR, IR, 그리고 전기 흡수 스펙트럼에 대한 pHdudgid에 의하여 규명하였다. 이온화형태, 전기적 전이 그리고 해리상수에 대하여 설명하였다. 구리 착화합물은 등방형 ESR스펙트럼이었으며 자기적으로 궤도 기여를 갖는 묽은 성질이었다. 상세한 DTA데이타를 얻었고, 그 결과를 토론하였다.

• Archives of Pharmacal Research
• /
• 제2권1호
• /
• pp.49-64
• /
• 1979

In an atempt to elucidate further physicochemical properties of furosemide-PVP coprecipitates, extensive investigations such as TLC, UV,IR, NMR, X-ray diffraction, TGA and DTA studies were carried out for the furosemide test systems. X-ray diffraction studies revealed that the pure furosemide and the furosemide contained within a physical mixture were crystalline in nature. However, there was no crystallinity evident in the 1:5 furosemide-PVP 40,000 coprecipitate system, even after standing for two years. The various ratio furosemide-PVP 40,000 coprecipitate systems revealed that the coprecipitate containing a greater amount of PVP 40,000 than that of furosemide showed a crystalline state of furosemide and that the minimum amounts of PVP to make amorphous form of furosemide was 1:1 ratio of furosemide to PVP. From the furosemide-PVP coprecipitate systems with PVP of different molecular weights of 10,000, 40,000 and 360,000, all the 1:1 ratio coprecipitates did not exhibit any crystallinity of furosemide, whereas all the 2:1 ratio coprecipitates showed a presence of crystalline furosemide. All the coprecipitated preparations with PEG 4,000 and with PEG 6,000 showed the diffraction peaks indicating the presence of crystalline furosemide. The comparison of infrared spectra of the physical mixture and the coprecipitate showed an interaction such as association between the functional groups of furosemide and PVP in the molecular level, whereas the studies by TLC, UV and NMR showed its dissociation in methanol solution. The weight losses in TGA curves showed all the same patterns. However, a little different transition form in DTA thermograms was shown between the physical mixture and the coprecipitate, indicating the different thermal property.