• 제목/요약/키워드: functional composites

검색결과 295건 처리시간 0.028초

Silane Coupling Agent 첨가에 의한 MDF Cement Composite의 수분안정성 연구 (The Study of Water Stability of MDF Cement Composite by Addition of Silane Coupling Agent)

  • 노준석;김진태;박춘근;오복진;최상홀
    • 한국세라믹학회지
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    • 제35권5호
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    • pp.421-428
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    • 1998
  • 순수 HAC/PVA 계 및 epoxy 수지와 urethane이 첨가된 HAC/PVA 계 MDF 시멘트 복합재료에 서로 다른 관능기를 갖는 3종류의 silane coupling agent를 첨가하여 강도 및 수분안정성에 대한 영향을 살펴보고 기공율 분석을 통해 미세구조와 강도의 관계를 살펴보았다. Silane의 관능기에 따라 각각의 MDF 시멘트 복합재료의 강도 및 수분안정성 향상에 대한 효과가 다른 것을 알 수 있었다. 순수 PVA 메트릭스의 경우에 대해서는 vinyl 기를 갖는 silane이 효과적인 영향을 나타내었으며 epoxy수지가 첨가된 MDF 시멘트에 대해서는 epoxy-methoxy 기를 갖는 silane이, 그리고 urethane이 첨가된 MDF 시멘트에 대해서는 diamine 기의 silane이 효과적이었다. Silane의 첨가량에 따라서는 urethane이 첨가된 MDF 시멘트 복합재료의 경우, diamine 기의 silane이 많이 첨가될수록 수분안정성이 향상되었으며 특히 2wt%의 silane을 첨가하고 wqrm press를 이용하여 성형하였을 때 건조 강도는 약 20% 향상되었으며 습윤강도는 40~70%까지 크게 향상되었다. 이는 기공율과 밀접한 관계가 있음을 알 수 있었다. Epoxy 수지가 첨가된 MDF 시멘트의 경우에서도 2wt%의 silane 첨가까지는 그 첨갈향이 많아질수록 강도가 향상되는 것을 알 수 있었지만 과량의 silane(4wt%)이 첨가될 경우에서는 오히려 특성저하가 나타났다.

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Extension of a new tailoring optimisation technique to sandwich shells with laminated faces

  • Icardi, Ugo
    • Structural Engineering and Mechanics
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    • 제43권6호
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    • pp.739-759
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    • 2012
  • The tailoring optimization technique recently developed by the author for improving structural response and energy absorption of composites is extended to sandwich shells using a previously developed zig-zag shell model with hierarchic representation of displacements. The in-plane variation of the stiffness properties of plies and the through-the thickness variation of the core properties are determined solving the Euler-Lagrange equations of an extremal problem in which the strain energy due to out-of-plane strains and stresses is minimised, while that due to their in-plane counterparts is maximised. In this way, the energy stored by unwanted out-of-plane modes involving weak properties is transferred to acceptable in-plane modes. As shown by the numerical applications, the critical interlaminar stress concentrations at the interfaces with the core are consistently reduced without any bending stiffness loss and the strength to debonding of faces from the core is improved. The structural model was recently developed by the author to accurately describe strain energy and interlaminar stresses from the constitutive equations. It a priori fulfills the displacement and stress contact conditions at the interfaces, considers a second order expansion of Lame's coefficients and a hierarchic representation that adapts to the variation of solutions. Its functional d.o.f. are the traditional mid-plane displacements and the shear rotations, so refinement implies no increase of the number of functional d.o.f. Sandwich shells are represented as multilayered shells made of layers with different thickness and material properties, the core being treated as a thick intermediate layer.

X-ray Photoelectron Spectroscopic Analysis of Modified MWCNT and Dynamic Mechanical Properties of E-beam Cured Epoxy Resins with the MWCNT

  • Lee, Young-Seak;Im, Ji-Sun;Yun, Seok-Min;Nho, Young-Chang;Kang, Phil-Hyun;Jin, Hang-Kyo
    • Carbon letters
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    • 제10권4호
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    • pp.314-319
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    • 2009
  • The surface treatment effects of reinforcement filler were investigated based on the dynamic mechanical properties of mutiwalled carbon nanotubes (MWCNTs)/epoxy composites. The as-received MWCNTs(R-MWCNTs) were chemically modified by direct oxyfluorination method to improve the dispersibility and adhesiveness with epoxy resins in composite system. In order to investigate the induced functional groups on MWCNTs during oxyfluorination, X-ray photoelectron spectroscopy was used. The thermo-mechanical property of MWCNTs/epoxy composite was also measured based on effects of oxyfluorination treatment of MWCNTs. The storage modulus of MWCNTs/epoxy composite was enhanced about 1.27 times through oxyfluorination of MWCNTs fillers at $25^{\circ}C$. The storage modulus of oxyfluorinated MWCNTs (OF73-MWCNTs) reinforced epoxy composite was much higher than that of R-MWCNTs/epoxy composite. It revealed that oxygen content led to the efficient carbon-fluorine covalent bonding during oxyfluorination. These functional groups on surface modified MWCNTs induced by oxyfluorination strikingly made an important role for the reinforced epoxy composite.

Realistic adsorption behaviors of the copper onto the functionalized CNTs

  • 박미나;김병현;이광렬
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2011년도 제40회 동계학술대회 초록집
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    • pp.476-476
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    • 2011
  • Introduction of CNTs into a metal matrix has been considered to improve the mechanical properties of the metal matrix. However, the binding energy between metals and pristine CNTs wall is known to be so small that the interfacial slip between CNTs and the matrix occurs at a relatively low external stress. The interfacial strength between CNT and metal matrix is thus one of the key factors for successful development of the CNT/metal composites. Defective or functionalized CNT has been considered to enhance the interfacial strength of nanocomposites. In the present work, we design the various realistic hybrid structures of the single wall CNT/Cu complexes and characterize the interaction between single wall CNTs and Cu nano-particle and Cu13 cluster using first principle calculations. The characteristics of functionalized CNTs with various surface functional groups, such as -COOH, -OH, and -O interacting with Cu are investigated. We found that the binding energy can be enhanced by the surface functional group including oxygen since the oxygen atom can mediate and reinforce the interaction between carbon and Cu. These results strongly support the recent experimental work which suggested the oxygen on the interface playing an important role in the excellent mechanical properties of the CNT/Cu composite.

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자연에서 배운 마이크로/나노구조물을 이용한 초발수 표면 (Micro/nanostructured Superhydrophobic Surface)

  • 임현의;박준식;김완두
    • Elastomers and Composites
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    • 제44권3호
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    • pp.244-251
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    • 2009
  • 최근 들어, 자연의 기능성 표면을 모사하여 공학적으로 이용하려는 연구가 전세계적으로 급격히 증가하고 있다. 자연계에 존재하는 표면의 여러 기능을 우리 생활에 응용할 수 있다면, 현재 인류가 직면하고 있는 환경오염, 에너지고갈, 물/식량 부족 등의 문제들을 해결하는데 큰 도움이 될 뿐만 아니라, 우리가 일상생활에 사용하는 많은 제품들의 표면 기능을 고도화시킬 수 있기 때문이다. 이 글에서는 다양한 기능을 가진 자연의 표면 중 마이크로/나노구조물을 이용하여 초발수 특성을 갖는 표면에 대하여 살펴보고 초발수 표면의 이론적인 배경 및 초발수 표면을 구현하기 위한 여러 연구들에 대하여 소개하고자 한다.

고주파유도 가열에 의한 나노구조 Fe-Si3N4 복합재료의 합성 및 급속소결 (Rapid Sintering and Synthesis of a Nanocrystalline Fe-Si3N4 Composites by High-Frequency Induction Heating)

  • 고인용;두송이;도정만;윤진국;박상환;손인진
    • 대한금속재료학회지
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    • 제49권9호
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    • pp.715-719
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    • 2011
  • Nanopowders of $Fe_3N$ and Si were fabricated by high-energy ball milling. A dense nanostructured $12Fe-Si_3N_4$ composite was simultaneously synthesized and consolidated using a high-frequency induction-heated sintering method for 2 minutes or less from mechanically activated powders of $Fe_3N$ and Si. Highly dense $12Fe-Si_3N_4$ with a relative density of up to 99% was produced under simultaneous application of 80 MPa pressure and the induced current. The microstructure and mechanical properties of the composite were investigated.

Triazine Thiol 유도체(誘導體)에 의한 1-Chlorobutadiene-Butadiene Copolymer의 안정화효과(安定化效果)에 관한 연구(硏究) (A Study on the Stabilization Effects of 1-Chlorobutadiene-Butadiene Copolymer by Triazine Thiol Derivative)

  • 유종선;산하진삼;백남철
    • Elastomers and Composites
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    • 제22권2호
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    • pp.109-120
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    • 1987
  • In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of CB-BR was attemped through stabilization. At first the stabilization effect of CB-BR and the concentration dependancy in CB-BR were determined. Then, triazine thiol derivative(BPTT) was synthesized by reacting p-aminodiphenylamine with cyanuric chloride. Further the functional mechanism and the effects of the antioxidants were investigated using BPTT together with other various antioxidants in liquid and solid states. The results obtained are as follows: 1) The aging of CB-BR depended on the concentration and temperature. Thus, at a low temperature of $50^{\circ}C$, the aging proceeded with gel formation; at high temperature above $100^{\circ}C$ and in above 4wt% concentration, the aging occured by the formation of gel. And in concentrations below that, the aging proceeds with a decomposition caused by oxygen attacked to elastomer molecules. 2) The effect of antioxidation of CB-BR in the liquid state was at it's best when the MBIZ and BPTT were used at $110^{\circ}C$, 4hrs after the oxidation. 3) The effect of antioxidation of CB-BR in the solid state was the best choice the simultaneous use of NDBC and BPTT at $50^{\circ}C$, 30days after the oxidation.

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Effect of Cross-Linking Characteristic on the Physical Properties and Storage Stability of Acrylic Rubber

  • Seong-Guk Bae;Min-Jun Gim;Woong Kim;Min-Keun Oh;Ju-Ho Yun;Jung-Soo Kim
    • Elastomers and Composites
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    • 제58권3호
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    • pp.136-141
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    • 2023
  • Polyacrylic rubber (ACM) is well known for its excellent heat resistance and chemical stability. Additionally, its performance can be readily manipulated by modifying its functional groups, rendering it highly attractive to various industries. However, extreme climate changes have necessitated an expansion of the operating temperature range and lifespan of ACM products. This requires the optimization of both the compounding process and functional-group design. Hence, we investigated the relationship between the cross-linking system and mechanical properties of an ACM with a carboxylic cure site. The crosslink density is determined by chemical kinetics according to the structure of additives, such as diamine crosslinkers and guanidine accelerators. This interaction enables the manipulation of the scotch time and mechanical properties of the compound. This fundamental study on the correlation analysis between cross-linking systems, physical properties, and storage stability can provide a foundation for material research aimed at satisfying the increasingly demanding service conditions of rubber products.

전복과 천연 식물류 복합물의 항산화 및 알코올대사 효소 활성 (Antioxidant and Alcohol Dehydrogenase Activity of Water Extracts From Abalone Containing Medicinal Plants)

  • 신정혜;이수정;최덕주;강민정;성낙주
    • 한국식품조리과학회지
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    • 제24권2호
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    • pp.182-187
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    • 2008
  • This study was performed to evaluate the possible production of a functional beverage derived from abalone and with several plants (AP). Five types of AP composites were prepared having different medicinal plant compositions (AP- I : abalone, garlic, jujube, Chinese matrimony fruit, dried orange peel, licorice root, zinger, honey; AP- II: abalone, garlic, black bean, Chinese matrimony fruit, cornus fruit, licorice root, zinger, honey; AP-III : abalone, jujube, arrow root, milk vetch, dried orange peel, licorice root, zinger, honey; AP-N: abalone, black bean, arrow root, milk vetch, cornus fruit, liquorice root, zinger, honey; AP-V : abalone, garlic, Chinese matrimony fruit, milk vetch, licorice root, zinger, honey). In vitro analysis were performed to examine the antioxidant contents and alcohol dehydrogenase activities of the composites. AP- II had the highest total phenol contents ($28.55{\pm}1.56\;mg/l00\;g$), and AP- V the highest level of flavonoids ($47.61{\pm}1.58\;mg/l00\;g$). At $78.89{\pm}0.16%$, AP- V displayed the strongest electron donating ability followed by AP-II($57.99{\pm}0.21%$) and API ($37.66{\pm}0.20%$). Reducing power was also significantly higher in AP- V. The Hydroxyl radical scavenging and SOD-like activities of all composites were less than 15% and 20%, respectively. At 12.5% alcohol concentration, ADH activity ranged from $114.47{\pm}2.18{\sim}121.39{\pm}4.36%$ and ALDH activity ranged from $100.04{\pm}2.90{\sim}129.54{\pm}4.80%$; AP- I , AP- II, and AP- Vin 12.5% of alcoholic concentration. The composites of AP- I , AP- II, and AP- V, all containing garlic and Chinese matrimony fruit, were significantly stronger than AP-III and AP-N. Finally, also at 12.5% alcoholic concentration, the ALDH activity of AP- V was higher than its ADH activity.

활성탄소섬유 표면의 염산처리효과와 TiO2 형성에 관한 분석 (The analysis for the HCl modification effect and formation of TiO2 on activated carbon fiber surface)

  • 오원춘;한상범;배장순
    • 분석과학
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    • 제20권4호
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    • pp.279-288
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    • 2007
  • 본 연구에서는 염산처리에 의하여 표면 개질된 활성탄소 섬유에 TNB (titanium n-butoxide) 용액을 침투시켜 $ACF/TiO_2$ 광촉매를 제조하였다. 염산 처리에 의하여 표면 기능기가 증가된 다공성 탄소에 형성된 $TiO_2$의 특성화에 연구의 관점을 두었다. TNB가 $TiO_2$로 변화되는 산처리 효과는 $ACF/TiO_2$ 광촉매제조에 상당히 중요한 요소임을 확인하였다. 표면 특성분석 결과로부터, BET 비표면적과 전체 동공부피는 산처리 양이 증가함에 따라 표면의 이산화티탄 화합물 형성과 함께 감소함을 나타내었다. 염산처리에 의해 형성된 $ACF/TiO_2$ 계에 대한 X-선 회절 변화로부터, 염산을 처리하지 않은 FT와 0.05, 0.1 M 처리된 FT1, FT2의 3가지 시료의 경우, 주요한 회절선의 피크는 아나타제의 결정상을 나타내었으며, 0.5M 처리된 FT3의 경우 아나타제와 루타일의 두 가지 형상이 나타났다. SEM 결과로부터, 전처리 하기전과 후에 활성탄소섬유 주변에 형성된 화합물들의 분포가 현저하게 다름을 알 수 있었으며, 이러한 현상은 산처리 효과의 우수성을 설명하고 있다. EDX 결과에 의하면, 모든 시료의 스펙트럼은 C, Ti와 O의 피크가 주요한 특징적 피크로 크게 나타났음을 보여 주고 있다. 마지막으로 MB (methylene blue)의 제거 효율에 근거하여, MB 농도 감소는 활성탄소섬유의 흡착효과와 $TiO_2$의 우수한 광분해 효과에 대한 두 가지 복합적인 결과로 설명할 수 있다.