• Title/Summary/Keyword: IFSS

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Study on the Flow Characteristics of the Epoxy Resin w.r.t. Sizing Materials of Carbon Fibers (탄소섬유 사이징에 따른 에폭시 수지 유동 특성에 관한 연구)

  • Lim, Su-Hyun;On, Seung Yoon;Kim, Seong-Su
    • Composites Research
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    • v.31 no.6
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    • pp.379-384
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    • 2018
  • This paper aims to study flow characteristics of epoxy resin w.r.t. the sizing agents treated on the carbon fibers which have the same surface morphologies before sizing treatment. Dynamic contact angle (DCA) was measured to evaluate wettability of a single carbon fiber. Wicking test and Vacuum Assisted Resin Transfer Molding (VARTM) were performed to find relation between DCA measurement results and impregnation characteristics. In addition, surface properties of the carbon fibers such as surface free energy and chemical compositions were measured and interfacial shear strength (IFSS) between the carbon fiber and the resin were experimentally characterized by using micro-droplet tests. According to these experimental results, the sizing agent for carbon fibers should have appropriate level of surface free energy and good chemical compatibility with the resin to reconcile resin flow characteristics and interfacial strength.

Cloning and Characterization of Soybean IFS (Isoflavone Synthase) Genes from Korean Cultivar, Sinpaldalkong (신팔달콩 유래 IFS (isoflavone synthase)유전자 클로닝 및 기능 규명)

  • Park, Hayng-Mi;Shin, Sang-Hyun;Ko, Jong-Min;Yi, Gi-Hwan;Nam, Min-Hee;Chung, Young-Soo;Chung, Won-Bok;Lee, Jai-Heon;Park, Seong-Whan
    • Journal of Life Science
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    • v.14 no.1
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    • pp.38-44
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    • 2004
  • Two genes, SinIFS1 and SinIFS2 from Korean soybean cultivar, Sinpaldalkong known as one of isoflavonerich cultivars, were cloned with PCR and degenerate primers. The sequences of two genes were analyzed with previously reported IFS genes of leguminous plants and their expression pattern in various environmental conditions was surveyed. The genomic clone of SinIFS1 contained 1,828bp nucleotides and encoded a polypeptide of 521 amino acids, and 1912bp nucleotides and a polypeptide of 521 amino acids for SinIFS2. Both genes included several conserved motifs, oxygen binding and activation (A/G-G-X-E/D-T-T/S), ERR triad (E...R....R), and heme binding (F-X-X-G-X-R-X-C-X-G) domain, which are typical in any member of cytochrome P45O superfamily. Very high sequence homology (>98%) was observed in the comparison with other IFSs of legumes. In the northern blot analysis to check the expression and increase of SinIFS1 to various environmental renditions (low temperature, light, dark, UV, and fungal elicitor), the most significant induction, more than 6 times of transcript level compared to the dark treatment as a control, was observed from the fungal elicitor treatment. The next up-regulated expression was from UV treatment (4${\times}$), low temperature and light conditions.

Curing Behavior and Interfacial Properties of Electrodeposited Carbon Fiber/Epoxy Composites by Electrical Resistivity Measurement under Tensile/Compressive Tests (전기증착된 탄소섬유/에폭시 복합재료의 인장/압축 하중하에서의 전기저항 측정법을 이용한 경화 및 계면특성)

  • Park, Joung-Man;Lee, Sang-Il;Kim, Jin-Won
    • Journal of Adhesion and Interface
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    • v.2 no.1
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    • pp.9-17
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    • 2001
  • Curing behavior and interfacial properties were evaluated using electrical resistance measurement and tensile/compressive fragmentation test. Electrical resistivity difference (${\Delta}R$) during curing process was not observed in a bare carbon fiber. On the other hand, ${\Delta}R$ appeared due to the matrix contraction in single-carbon fiber/epoxy composite. Logarithmic electrical resistivity of the untreated single-carbon fiber composite increased suddenly to the infinity when the fiber fracture occurred under tensile loading, whereas that of the ED composite reached relatively broadly up to the infinity. Comparing to the untreated case, interfacial shear strength (IFSS) of the ED treated composite increased significantly in both tensile fragmentation and compressive Broutman test. Microfailure modes of the untreated and the ED treated fiber composite showed the debonding and the cone shapes in tensile test, respectively. For compressive test, fractures of diagonal slippage were observed in both untreated and the ED treated composite. Sharp-end shape fractures exhibited in the untreated composite, whereas relatively dull fractures showed in the ED Heated composite. It is proved that ED treatments affected differently on the interfacial adhesion and microfailure mechanism under tensile/compressive tests.

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Improvement of Interfacial Adhesion of Plasma Treated Single Carbon Fiber Reinforced CNT-Phenolic Nanocomposites by Electrical Resistance Measurement and Wettability (젖음성 및 전기저항 측정을 이용한 플라즈마 처리된 단일 탄소섬유 강화 탄소나노튜브-페놀수지 나노복합재료의 계면접착력 향상)

  • Wang, Zuo-Jia;Kwon, Dong-Jun;Gu, Ga-Young;Park, Jong-Kyoo;Lee, Woo-Il;Park, Joung-Man
    • Journal of Adhesion and Interface
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    • v.12 no.3
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    • pp.88-93
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    • 2011
  • Optimal dispersion and fabrication conditions of carbon nanotube (CNT) embedded in phenolic resin were determined by electrical resistance measurement; and interfacial property was investigated between plasma treated carbon fiber and CNT-phenolic composites by electro-micromechanical techniques. Wettability of carbon fiber was improved significantly after plasma treatment. Surface energies of carbon fiber and CNT-phenolic nanocomposites were measured using Wilhelmy plate technique. Since surface activation of carbon fiber, the advancing contact angle decreased from $65^{\circ}$ to $28^{\circ}$ after plasma treatment. It was consistent with static contact angle results of carbon fiber. Work of adhesion between plasma treated carbon fiber and CNT-phenolic nanocomposites was higher than that without modification. The interfacial shear strength (IFSS) and apparent modulus also increased with plasma treatment of carbon fiber.

Nondestructive Evaluation and Microfailure Mechanisms of Single Fibers/Brittle Cement Matrix Composites using Electro-Micromechanical Technique and Acoustic Emission (Electro-Micromechanical 시험법과 Acoustic Emission을 이용한 단섬유/시멘트 복합재료의 미세파괴 메커니즘과 비파괴적 평가)

  • 박종만;이상일;김진원;윤동진
    • Composites Research
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    • v.14 no.3
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    • pp.18-31
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    • 2001
  • Interfacial and microfailure properties of the modified steel, carbon and glass fibers/cement composites were investigated using electro-pullout test under tensile and compressive tests with acoustic emission (AE). The hand-sanded steel composite exhibited higher interfacial shear strength (IFSS) than the untreated and even neoalkoxy zirconate (Zr) treated steel fiber composites. This might be due to the enhanced mechanical interlocking, compared to possible hydrogen or covalent bonds. During curing process, the contact resistivity decreased rapidly at the initial stage and then showed a level-off. Comparing to the untreated case, the contact resistivity of either Zr-treated or hand-sanded steel fiber composites increased to the infinity at latter stage. The number of AE signals of hand-sanded steel fiber composite was much more than those of the untreated and Zr-treated cases due to many interlayer failure signals. AE waveforms for pullout and frictional signals of the hand-sanded composite are larger than those of the untreated case. For dual matrix composite (DMC), AE energy and waveform under compressive loading were much higher and larger than those under tensile loading, due to brittle but well-enduring ceramic nature against compressive stress. Vertical multicrack exhibits fur glass fiber composite under tensile test, whereas buckling failure appeared under compressive loading. Electro-micromechanical technique with AE can be used as an efficient nondestructive (NDT) method to evaluate the interfacial and microfailure mechanisms for conductive fibers/brittle and nontransparent cement composites.

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