• Title/Summary/Keyword: 실리카

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Transport Properties of Fluorinated Polyimide/PMMA-g-Silica Nanocomposite Membrane (PMMA가 그래프트된 실리카 나노입자를 포함한 불소계 폴리이미드 복합 분리막의 기체 투과 특성)

  • Kwon, Yu-Mi;Im, Hyun-Gu;Kim, Joo-Heon
    • Polymer(Korea)
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    • v.34 no.1
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    • pp.1-7
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    • 2010
  • To enhance the transport properties of gas separation membrane, we prepared 6FDA-6FpDA based polyimide membrane with PMMA-graft-silica nanoparticles. The silica was grafted PMMA which is miscible with 6FDA-based polyimide after surface treatment by 3-methacryloxypropyltrimethoxysilane ($\gamma$-MPS). The untreated silica/6FDA-6FpDA membrane showed greater permeability and less selectivity than PMMA-g-silica/6FDA-6FpDA due to its low dispersion. The transport properties of PMMA-g-silica/6FDA-GFpDA membrane were measured as a function of filler concentration. These membranes were evaluated using pure gases (He, $O_2$, $N_2$, $CO_2$). The increase in permeation was attributed to changes in the free volume distribution until 1 wt%. After 1 wt%, the permeability was decreased by excess silica which decreased effective area in polymer matrix. The selectivity was decreased with increasing permeability on the whole. However, the selectivity of $CO_2$ showed more enhance value.

A study on the synthesis of porous silica from a sodium silicate (물유리로부터 다공성 실리카 제조에 관한 연구)

  • Yoo, Jeong-Kun;Keum, Young-Ho;Shon, Byung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.4
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    • pp.2519-2525
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    • 2014
  • WeI have studied the process for synthesizing porous silica with a specific surface area of minimum $800m^2/g$ by adding surfactant [Poly Etylene Glycol(PEG) and Hydroxy Propyl Cellulose(HPC)] to the sol-gel reaction between sodium silicate and hydrochloric acid. NaCl, the by-product of the sol-gel reaction, was water cleaned and removed; when 200 ml of water was used to clean 50 g of silica gel, NaCl remaining in the silica gel was reduced to maximum 0.81wt%. The appropriate level of surfactant for silica gel synthesizing proved to be below 5%. As a result of the experiment, for the silica synthesized by adding surfactant of HPC(2.5%)+PEG(2.5%), the surfactant area was $860m^2/g$ and grain size was $20-50{\mu}m$. From this study, we have concluded that it is of industrial significance that specific surface area is improved and silica of a regular grain size is obtained just by adding surfactant in the gel process or drying process of silica.

A Study on Physical Properties of Epoxy Resin Filled with Surface-treated Silica: I. Surface-treating of Silica and Properties of Mixtures (표면처리된 실리카를 충전한 에폭시 수지계의 물성에 관한 연구 I. 실리카의 표면처리 및 혼합 물성)

  • Hong, Suk-Pyo;Choi, Sang-Goo
    • Applied Chemistry for Engineering
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    • v.1 no.1
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    • pp.63-72
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    • 1990
  • Surface of crystalline silica was sequentially reacted with silane(A 187), liquid rubber(CTBNx8) and vinyl monomer(AA, MMA, 2-HEA, GMA) in existance of amines(TEA, CTMAB, BETAC) or peroxide(BPO). By mixing it with epoxy resin at a ratio 0~36%(volume %) of total component, liquid properties of mixtures was investigated experimentally. i) Coating ratio depended on quantity and sorts of catalyst. ii) Total coating of 2.5~5.8% was attained by using 0.1~2.0% of catalyst. iii) Treated surfaces represented each different features in according to sorts of treatment. iv) Silane/rubber or silane/rubber/vinyl represented lower viscosity and settling than non-treated or silane-treated.

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Mechanical Properties of Polymeric Dental Restorative Composites Filled With Silica Treated by Heat at Various Temperatures (다양한 온도에서 열처리시킨 실리카가 충진된 치아수복용 고분자 복합체의 기계적 물성)

  • Kim, Ohyoung;Lee, Jung Soo;Seo, Kitaek;Kang, Doo Whan;Kang, Ho-Jong;Gong, Myoung-Seon;Oh, Myoung-Hwan
    • Applied Chemistry for Engineering
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    • v.16 no.4
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    • pp.549-555
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    • 2005
  • To evaluate the posterior and anterior restoration of polymeric dental restorative composite (PDRC), PDRC was prepared using a silica filler treated by heat at various temperatures. Compressive strength (CS) and diametral tensile strength (DTS) values were investigated to study the effect of a heat-treated silica on the mechanical properties of PDRC using the recommended dental specifications. Both the particle size and specific volume of silica were decreased upon increasing the heat treatment temperature. CS and DTS values of PDRC containing a heat-treated silica showed 1.2 and 1.3 times, respectively, higher than that of the PDRC containing a neat silica. Also, it was found that the lower heat treatment temperature, the better mechanical properties of PDRC were observed because there was less agglomeration between silica particles. Specially, PDRC using a silica treated at $600^{\circ}C$ showed superior mechanical strength.

Filler-Elastomer Interactions 5. Effect of Silane Surface Treatment on Interfacial Adhesion of Silica/Rubber Composites (충전재-탄성체 상호작용 5. 실란 표면처리가 실리카/고무 복합재료의 계면 특성에 미치는 영향)

  • 박수진;조기숙
    • Polymer(Korea)
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    • v.26 no.4
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    • pp.445-451
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    • 2002
  • In this work, the adsorption characteristics and mechanical interfacial properties of treated silicas by silane coupling agents, such as, ${\gamma}$-methacryloxy propyl trimethoxy silane (MPS), ${\gamma}$-glycidoxy propyl trimethoxy silane (GPS), and ${\gamma}$-mercapto propyl trimethoxy silane (MCPS), were investigated. The equilibrium spreading pressure ($pi_e$), surface free energy ($gamma_s$ s/), and specific surface area ($S_{BET}$) were studied by the BET method with $N_2$/77 K adsorption. The developments of nonpolar functional groups of the silica surfaces treated by silane coupling agents led to the increase in the $S_{BET}$, $pi_e$, and $gamma_s$, resulting in the improved tearing energy ($G_{mc}$)of the silica/rubber composites. The composites treated by MPS showed the superior mechanical interfacial properties in these systems. These results explained by changing of crystalline size, dispersion, agglomerate, and surface functional group of silica/rubber composites.

Preparation and characterization of nanoporous monolith with high thermal insulation performance (나노 기공성 단열 실리카 모노리스 제조 및 특성 연구)

  • Choi, Hyun-Muk;Kim, Seong-Woo
    • Journal of the Korean Applied Science and Technology
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    • v.31 no.1
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    • pp.83-91
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    • 2014
  • In this study, we synthesized two different silica monoliths by using sol-gel, solvent exchange, surface modification, ambient pressure drying processes, and surfactant-based templating technique followed by calcination process. All of the prepared two silica monoliths showed crack-free appearance with fairly good transparency, and furthermore were confirmed to have extremely high porosity, specific surface area, and mean pore size below 30 nm. The silica aerogel sample exhibited finer and more homogeneous nano-sized pore structure due to spring back effect caused by surface modification, which resulted in better thermal insulation performance. Based on measured thermal conductivities and theoretical relationship, multi-layered glass window system in which silica monolith prepared in this study was inserted as a middle layer was revealed to have superior thermal insulation performance compared to conventional air-inserted glass window system.

Preparation and Growth of Silica Sol from Sodium Silicate (소디움실리케이트로부터 실리카 솔 제조(製造) 및 성장(成長))

  • Yoon, Ho-Sung;Kim, Chul-Joo;Kim, Sung-Don;Jang, Hee-Dong
    • Resources Recycling
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    • v.16 no.5
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    • pp.31-35
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    • 2007
  • The formation of silica sol from sodium silicate solution and the growth of silica sols were investigated in this study. The $SiO_2$ content of 2% in sodium silicate solution was proper to oxidize sodium silicate with sulfuric acid. After the removal of sodium ions in sodium silicate solution, the pH of silicate solution had to be controlled above 9 for a stable silicate solution. The silica sol, which size is about 10 nm, could be prepared by heating the mixed solution of sodium silicate and silicate solution removed sodium ions at pH 10 and 80. And the silica sol grew into about 50 nm as silicate solution was added to silica sol solution.

Nanoimprinting Pattern Formation Using Photo-Curable Acrylate Composites (광경화성 아크릴레이트 복합체를 이용한 나노 임프린트 패턴 형성)

  • Kim, Sung-Hyun;Park, Sun-Hee;Moon, Sung-Nam;Lee, Woo-Il;Song, Ki-Gook
    • Polymer(Korea)
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    • v.36 no.4
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    • pp.536-541
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    • 2012
  • The effects of silica content were studied on UV curing characteristics and defect formations in imprinted patterns of hundreads nanometer size for the photo-curable imprinting composites with silica particles. An increase in elasticity and a decrease in shrinkage were observed with an increase in silica content in the imprinting resin which was UV cured at room temperature. However, the patterned nano-pillars were stuck together with neighboring nano-pillars if the amount of silica is more than 7 wt%. This can be ascribed to the increased viscosity of imperfectly cured resin due to the obstruction of the photo-reaction by silica particles. Addition of silica to the imprinting resin is useful in enhancing the strength of the cured resin although it is difficult to get good imprinted patterns for the resin with more than 7 wt% of silica due to the reduction of photo-reaction conversion.

Influence of Filler Systems and Microstructures of SBR on Stress Softening Effect of SBR Vulcanizates (SBR의 미세 구조와 보강 시스템이 SBR 가황물의 응력 풀림 효과에 미치는 영향)

  • Choi, Sung-Seen;Han, Dong-Hun;Woo, Chang-Su
    • Elastomers and Composites
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    • v.41 no.3
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    • pp.164-171
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    • 2006
  • Stress softening behaviors of SBR vulcanizates reinforced with silica or carbon black were studied. Two types of SBR with different 1,2-unit contents of 18 and 60 wt% were used and three filler systems of carbon black and silica with/without silane coupling agent were employed. Stress softening behaviors of the SBR vulcanizates were varied with the SBR types as well as the filler systems. The silica-filled rubber specimens had higher residual strains than the carbon black-filled ones. The residual strains of silica-filled vulcanizates were remarkably reduced by adding a silane coupling agent. The maximum loads at 50% maximum stretch of the carbon black-filled vulcanizates were lower than those of the silica-filled ones. On the contrary, the maximum loads at 200% maximum stretch of the carbon black-filled vulcanizates were higher than those of the silica-filled ones. The maximum loads of the specimens with the 1,2-unit content of 60 wt% are higher than those with the 1,2-unit content of 18 wt% irrespective of the filler systems.

Study on Silica Removal from Borated Water Using Reverse Osmosis Membranes in Nuclear Power Plants (역삼투막의 선택적 제거특성을 이용한 원자력발전소 붕산수 중의 실리카 제거에 관한 연구)

  • 윤석원;박광규
    • Membrane Journal
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    • v.7 no.4
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    • pp.167-174
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    • 1997
  • The concentration of silica is required to meet a certain level because silica affects fuel and materials integrity by forming a zeolite layer on fuel cladding surfaces. When the established Feed and Bleed method is employed, nuclear waste increase and the corresponding amount of boric acid is constantly consumed. This study concentrates on minimizing the amount of nuclear waste and consumption of boric acid. Using five different membranes, operating conditions such as temperatur, feed water flow rate, boric acid recovery and silica removal rate were examined. A silica-selective removal system was designed based on the above optimization procedures. Three-stage system was designed with two characteristically different membranes so that it could correspond with the different situation easily. Compared to the pevious results of the Feed and Bleed method, the current method showed that the amount of nuclear waste was reduced to 7%, and the consumption of boric acid to 15.7%.

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