• Elastomers and Composites
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• 제54권2호
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• pp.97-104
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• 2019

Emulsion styrene-butadiene rubber silica wet masterbatch (ESBR silica WMB) technology was studied to develop highly filled and highly dispersed silica compounds, involving the preparation of a composite by co-coagulating the modified silica and the rubber latex in a liquid phase. Previous studies have shown that when manufacturing ESBR silica WMB/Butadiene silica dry masterbatch (BR silica DMB) blend compounds, preparing BR silica dry masterbatch and mixing it with ESBR silica WMB gave excellent results. However, WMB still has the problem of lower crosslink density due to residual surfactants. Therefore, in this study, tetrabenzylthiuram disulfide (TBzTD) was added instead of diphenyl guanidine (DPG) in the ESBR silica WMB/BR silica DMB blend compounds and sulfur/CBS contents were increased to evaluate their cure characteristics, crosslink densities, mechanical properties, and dynamic viscoelastic properties. TBzTD was found to be more effective in increasing the crosslink density and to produce superior properties compared to DPG. In addition, with increasing sulfur/CBS contents, mechanical properties and rolling resistance were enhanced due to high crosslink density, but the abrasion resistance was not significantly changed because of the toughness.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.47-50
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• 2003

Carbon-silica membranes were Prepared by Pyrolyzing polyimide/silica composite obtained from ill-situ polymerization of alkoxy silanes via sol-gel reaction. In this study, effects of silica content and silica network in polyimide matrix were focused on the gas permeation and separation properties of the final carbon-silica membrane. The membranes prepared were characterized with a field emission scanning electron microscopy (FE-SEM), a solid state $^{29}$ Si nuclear magnetic resonance spectroscopy ($^{29}$ Si-NMR), an electron spectroscopy for chemical analysis (ESCA), a thermogravimetric analysis (TGA) and gas permeation tests.

• Elastomers and Composites
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• 제57권4호
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• pp.165-174
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• 2022

The effect of fumed silica loading on the thermal stability and mechanical properties of fluorosilicone (FVMQ) rubber was investigated. The distribution of fumed silica inside FVMQ was characterized using scanning electron microscopy, and the thermal stability of composites was evaluated using thermogravimetric analysis and by the changes in mechanical performance during thermo-oxidative aging. The function mechanism of fumed silica was studied by Fourier transform infrared spectroscopy. The results show that with increasing silica content, the crosslink density of composites, the modulus at 100%, and tensile strength also increased, whereas the elongation at break decreased. Furthermore, increasing the silica content of composites increased the initial decomposition temperature (T_d) and residual weight of the composite after exposure to nitrogen. In addition, the thermal oxidative aging experiment demonstrated improved aging resistance of the FVMQ composites, including lower change in tensile strength, elongation at break, and modulus at 100%.

• Composites Research
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• 제24권6호
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• pp.18-24
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• 2011

대기압 화염 플라즈마(APFP) 및 에폭시 실란(ES) 표면처리 한 실리카($V_f=40%$) 강화 고무복합재료의 기계적 특성에 대한 실험적 연구를 수행하였다. 고무복합재료의 인장강도는 평균 입자경이 감소할수록 크게 증가하였고, 평균 입자경 $2.2{\mu}m$일때, 기지(2.52MPa)에 비해 1.4배 증가하였다. 또한 APFP 및 EP의 처리로 인장강도가 각각 8.8~13.3%, 9.9~12.5% 향상되었다. 평균 입자경이 $26.6{\mu}m$일 때, 고무복합재료의 인장탄성율은 기지(0.88MPa)에 비해 2배 증가하였고, APFP 및 EP의 처리로 인장 탄성율이 각각 15.6~22.8%, 21.1~25.8% 증가되었다. 기존의 실란 커플링제 처리방법은 유기용제의 사용 등의 몇 가지 단점을 가지고 있지만, APFP 처리법은 기계적 특성을 향상시키는데 빠르고, 경제적이며 친환경적인 방법이라 판단된다.

• Advances in nano research
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• 제13권1호
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• pp.97-111
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• 2022

In the present article, silica nanoparticles (SNPs) were exploited to improve the tribological and mechanical properties of vinyl ester/glass fiber composites. To the best of our knowledge, there hasn't been any prior study on the wear properties of glass fiber reinforced vinyl ester SiO₂ nanocomposites. The wear resistance is a critical concern in many industries which needs to be managed effectively to reduce high costs. To examine the influence of SNPs on the mechanical properties, seven different weight percentages of vinyl ester/nano-silica composites were initially fabricated. Afterward, based on the tensile testing results of the silica nanocomposites, four wt% of SNPs were selected to fabricate a ternary composite composed of vinyl ester/glass fiber/nano-silica using vacuum-assisted resin transfer molding. At the next stage, the tensile, three-point flexural, Charpy impact, and pin-on-disk wear tests were performed on the ternary composites. The fractured surfaces were analyzed by scanning electron microscopy (SEM) images after conducting previous tests. The most important and interesting result of this study was the development of a nanocomposite that exhibited a 52.2% decrease in the mean coefficient of friction (COF) by augmenting the SNPs, which is beneficial for the fabrication/repair of composite/steel energy pipelines as well as hydraulic and pneumatic pipe systems conveying abrasive materials. Moreover, the weight loss due to wearing the ternary composite containing one wt% of SNPs was significantly reduced by 70%. Such enhanced property of the fabricated nanocomposite may also be an important design factor for marine structures, bridges, and transportation of wind turbine blades.

• Computers and Concrete
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• 제26권5호
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• pp.385-395
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• 2020

The influence of combination of nano silica and silica fume, as partial cement replacement materials, on the properties of concrete has been studied through the measurement of compressive strength. The compressive strength of concrete in terms of mean, standard deviation and with-in-test coefficient of variation related to the variation in the nominated parameters have also been developed. The compressive strength data developed experimentally has been analyzed using normal-probability distribution and partial safety factors of composite concretes have been evaluated by using first order second moment approach with Hasofer Lind's method. The use of Nano silica and silica fume in concrete decreases the partial safety factor of concrete i.e., increase the reliability of concrete. The experimental results show that the properties of concrete having nano silica and silica fume in combination were better than that of a plain concrete. The SEM test results showing the level of Ca(OH)₂ in plain concrete and consumption level Ca(OH)₂ of concrete containing nano silica & silica fume have also been presented.

• 전기화학회지
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• 제8권2호
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• pp.77-81
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• 2005

전기화학적으로 이온을 흡착시켜 이온을 제거하는 capacitive deionization(CDI)공정용 전극으로 탄소에어로젤에 실리카젤이 첨가된 다공성 탄소에어로젤 복합전극을 사용하여 1,000ppm NaCl수용액에서 탈염 특성에 대한 충전과 방전시 시간에 따른 전류 변화, CDI효율을 조사하였다. Paste rolling법으로 제조된 $10\times10cm^2$다공성 탄소에어로젤 복합전극은 촉매 분야에서 활용되고 있는 다공성 지지체인 실리카젤을 첨가함으로써 CDI 반응진행에 대한 전극활물질 탈락이 없이 전극의 성형성이 크게 향상되었고, 친수성과 전극의 기계적 강도 증가 및 CDI 효율을 증가시킬 수 있었다. 이러한 45개의 전극을 하나의 묶음으로 네 개의 단을 직렬연결 하여, CDI 시스템을 구성하였고 충전 시에는 1.2V, 방전 시에는 0.001V를 각각 10분간 인가하여 실험한 결과 $99\%$ 이상의 CDI 효율을 달성하였다.

• Composites Research
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• 제18권6호
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• pp.48-53
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• 2005

본 연구에서는 방탄물성이 매우 우수한 알루미나-실리카계 방탄재료(PL-8)의 방탄물성을 향상시키기 위해 성형압력 및 소결온도를 변화시켰다. 물리/기계적 물성을 측정 한 후 성형작약(HEAT)/운동에너지(KE)탄에 대한 방탄물성을 측정하여 분석하였다. 그 결과 소결온도 $1235^{\circ}C$에서 성형작약탄에 대한 방탄물성이 가장 높았으며 기 개발된 알루미나-실리카계 방탄재료 (PL-8)에 비해 $22\%$ 방탄물성이 향상되었다.

• 전기학회논문지
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• 제67권11호
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• pp.1463-1470
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• 2018

In this study, 20 types of samples were prepared by mixing different kinds of inorganic materials to develop insulation materials for epoxy - based GIS substation equipment used under high voltage environmentally friendly insulation gas. One of the electrical characteristics, AC insulation breakdown experiment was performed. As mixing ratio of mixed heterogeneous inorganic materials, the dielectric breakdown strength was increased with increasing filler ratio of micro silica, micro silica : micro Alumina, 1:9, 3:7, 5:5, 7:3, 9:1, and decreased as the filling amount of micro alumina increased. The AC insulation breakdown characteristics were the best when the composition ratio was 9:1. The higher the content of silica, the better the interfacial properties, and the larger the alumina content ratio, the worse the interfacial properties.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.214-215
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• 2006

Colloidal Silica(CS)와 유기수지를 혼합하여 서로의 단점을 보완하는 나노복합재료를 합성하기 위해 친수성인 CS를 유기실란으로 표면처리하여 소수성화하고 유기수지와 복합체를 제조하였다. CS표면의 -OH기와 실란의 -OH기가 축합반응하여 화학결합을 형성함으로서 CS의 표면은 실란의 $CH_3$에 의해 소수성화되어 CS sol이 제조된다. CS sol과 유기수지는 공동용매에 의해 균일한 분산이 가능하고 필름 및 코팅제로의 제조가 가능하다. 사용된 무기물은 40nm 의 크기를 가지므로 가시광선영역의 빛을 산란하지 않아 투명하고 사용된 수지 또한 투명하여 우수한 광학적 특성을 나타낸다. 만들어진 필름은 CS의 영향으로 유기수지의 내열성보다 향상된 열분해온도와 높은 접촉각, 높은 절연율을 보였다.