• Title/Summary/Keyword: ILSS

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Electrodeposition onto the Surface of Carbon Fiber and Its Application to Composites (II) - CFRC with MVEMA and EMA Interphase - (탄소섬유 표면에의 고분자 전착과 복합재료 물성 (II) - MVEMA 및 EMA 계면상을 갖는 탄소섬유 복합재료 -)

  • Kim, Minyoung;Kim, Jihong;Bae, Jongwoo;Kim, Wonho;Hwang, Byungsun;Choi, Youngsun
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.336-342
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    • 1999
  • Various surface treatment techniques can be applied onto the surface of carbon fibers to increase interlaminar shear strength (ILSS). In a commerciaI treatment, first, surface of carbon fiber was oxidized, after that, a sizing agent was coated to improve handleability and adhesion to the matrix. Carbon fiber reinforced composites (CFRC) which is made of these fibers show excellent ILSS but show low vaIues of impact strength In this study, reactive and ductile interphase was introduced between fiber and matrix to increase both the ILSS and impact strength. By using electric conductivity of carbon fibers, flexible polymers which have ionizable group, i.e., MVEMA and EMA, were coated onto the surface (oxidized) of carbon fiber by the technique of electrodeposition. ILSS and impact strength of composites were evaluated according to the surface treatments, i.e., commercial sizing treatment, interphase introduction, and without sizing treatment. Izod impact strength and ILSS of CFRC were simultaneously improved in thc thickness range of $0.08{\sim}0.12{\mu}m$ of MVEMA interphase. Water resistance of the composites was decreased by introducing MVEMA interphase.

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A Study on the Preparation of the Eco-friendly Carbon Fibers-Reinforced Composites

  • Choi, Kyeong-Eun;Seo, Min-Kang
    • Carbon letters
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    • v.14 no.1
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    • pp.58-61
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    • 2013
  • In this work, the effect of catalysts on the mechanical properties of carbon fibers-reinforced epoxy matrix composites cured by cationic latent thermal catalysts, i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) was studied. Differential scanning calorimetry was executed for thermal characterization of the epoxy matrix system. Mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ($K_{IC}$), and specific fracture energy ($G_{IC}$). As a result, the conversion of neat epoxy matrix cured by BPH was higher than that of one cured by diaminodiphenyl methane (DDM). The ILSS, $K_{IC}$, $G_{IC}$, and impact strength of the composites cured by BPH were also superior to those of the composites cured by DDM. This was probably the consequence of the effect of the substituted benzene group of BPH catalyst, resulting in an increase in the cross-link density and structural stability of the composites studied.

Fabrication and Application of Nano-Fibers for Korean Post-Textile Industry (나노섬유의 제조와 응용 및 한국의 차세대 섬유산업)

  • 이재락;박수진;김효중;정효진;지승용;김준현
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.10a
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    • pp.3-6
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    • 2003
  • In this work, poly(ethylene oxide) nanofibers were fabricated by electrospinning to prepare nanofibers-reinforced composites. And the PEO powders-impregnated composites were also prepared to compare with physicochemical properties of nanofibers-reinforced composites. Morphology and fiber diameter of PEO nanofibers were determined by SEM observation. Mechanical interfacial properties of the composites were investigated in fracture toughness tests and interlaminar shear strength (ILSS) test. As a result, the fiber diameter decreased in increasing applied voltage. However the optimum condition for the fiber formation was 15 ㎸, resulting from increasing of jet instability at high voltage and the prepared PEO nanofibers were useful in fiber reinforced composites. The PEO-based nanofibers-reinforced composites showed an improvement of fracture toughness factors ($K_{IC} and G_{ IC}$) and ILSS, compared to the composites impregnated with PEO powders. These results were noted that the nanofibers had higher specific surface area and larger aspect ratio than those of the powder, which played an important role in improving the mechanical interfacial properties of the composites.

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Evaluation of Mechanical Properties of Carbon Fabrics Composite with Thermal Shock (열 충격에 따른 탄소 직물 복합재료의 역학적 특성 평가)

  • Kim, Jae-Hong;Lee, Jung-Ho;Jung, Kyung-Ho;Kang, Tae-Jin
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.11a
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    • pp.79-82
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    • 2005
  • In this study, mechanical properties of carbon fabrics composite under the thermal shock cycling were evaluated. Due to the interactions between fiber and polymer matrix, it is reasonable to conclude that both thermal cycles of thermal shock result in improvement of interlaminar shear strength(ILSS) for the longer conditioning time duration. The rise in ILSS may be attributed to the improved adhesion by cryogenic compressive stress and also by the post-curing strengthening effect. However, the flexural and tensile strength were decreased with increasing conditioning time of thermal cycle.

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Studies on ILSS and Acoustic Emission Properties of Carbon-Carbon Composites

  • Park, Soo-Jin
    • Carbon letters
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    • v.1 no.2
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    • pp.60-63
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    • 2000
  • In this work, the carbon fibers-reinforced carbon matrix composites made with different carbon char yields of phenolic resin matrix have been characterized by mechanical flexural tests for acoustic emission properties. The composites had been fabricated in the form of two-dimensional polyacrylonitrile based carbon fibers during the carbonization process. It was found that the composites made with the carbon char yield-rich of resin matrix result in better mechanical interfacial properties, i.e., the interlaminar shear strength (ILSS) of the composites. The data obtained from the acoustic emission monitored appeared to show that the composites made with carbon char yield-rich were also more ductile. From the acoustic emission results, the primary composite failure was largely depended on the debonding at interfaces between fibers and matrix. The interlaminar shear strengths of the composites were correlated with the acoustic emission results.

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Effect of Graphitic Nanofibers on Interfacial Adhesion and Fracture Toughness of Carbon Fibers-reinforced Epoxy Composites

  • Kim, Seong-Hwang;Park, Soo-Jin
    • Composites Research
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    • v.34 no.2
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    • pp.82-87
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    • 2021
  • The mechanical properties of carbon fiber-reinforced epoxy composites (CFRPs) are greatly dependent on the interfacial adhesion between the carbon fibers and the epoxy matrix. Introducing nanomaterial reinforcements into the interface is an effective approach to enhance the interfacial adhesion of CFRPs. The main purpose of this work was to introduce graphitic nanofiber (GNFs) between an epoxy matrix and carbon fibers to enhance interfacial properties. The composites were reinforced with various concentrations of GNFs. For all of the fabricated composites, the optimum GNF content was found to be 0.6 wt%, which enhanced the interlaminar shear strength (ILSS) and fracture toughness (KIC) by 101.9% and 33.2%, respectively, compared with those of neat composites. In particular, we observed a direct linear relationship between ILSS and KIC through surface free energy. The related reinforcing mechanisms were also analyzed and the enhancements in mechanical properties are mainly attributed to the interfacial interlocking effect. Such an effort could accelerate the conversion of composites into high performance materials and provide fundamental understanding toward realizing the theoretical limits of interfacial adhesion and mechanical properties.

Processing - Interlaminar Shear Strength Relationship of Carbon Fiber Composites Reinforced with Carbon Nanotubes (탄소나노튜브로 보강된 탄소섬유복합재의 제조공정과 층간전단강도)

  • Kim, Han-Sang
    • Composites Research
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    • v.24 no.5
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    • pp.34-38
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    • 2011
  • Carbon nanotubes (CNTs) have been widely investigated as reinforcements of CNT/polymer nanocomposites to enhance mechanical and electrical properties of polymer matrices since their discovery in the early 90's. Furthermore, the number of studies about incorporating CNTs into carbon fiber reinforced plastics (CFRP) to reinforce their polymer matrices is increasing recently. In this study, single-walled carbon nanotubes (SWNT) were dispersed in epoxy with 0.2 wt.% and 0.5 wt.%. Then, the SWNT/epoxy mixtures were processed to carbon fiber composites by a vacuum assisted resin transfer molding (VARTM) and a wet lay up method. The processed composite samples were tested for the interlaminar shear strength (ILSS). The relationship between the interlaminar shear strengths and processing, and the reinforcement mechanism of carbon nanotubes were investigated. CNT/epoxy nanocomposite specimens showed the increased tensile properties. However, the ILSS of carbon fiber composites was not enhanced by reinforcing the matrix with CNTs because of processing issues caused by increased viscosity of the matrix due to addition of CNTs particularly for a VARTM method.

Evaluation of Mechanical Property of Carbon Fiber/Polypropylene Composite According to Carbon Fiber Surface Treatment (탄소섬유 표면처리에 따른 탄소섬유/폴리프로필렌 복합재료의 기계적 물성 평가)

  • Han, Song Hee;Oh, Hyun Ju;Kim, Seong Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.6
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    • pp.791-796
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    • 2013
  • In this study, the mechanical properties of a carbon fiber/polypropylene composite were evaluated according to the carbon fiber surface treatment. Carbon fiber surface treatments such as silane coupling agents and plasma treatment were performed to enhance the interfacial strength between carbon fibers and polypropylene. The treated carbon fiber surface was characterized by XPS, SEM, and single-filament tensile test. The interlaminar shear strength (ILSS) of the composite with respect to the surface treatment was determined by a short beam shear test. The test results showed that the ILSS of the plasma-treated specimen increased with the treatment time. The ILSS of the specimen treated with a silane coupling agent after plasma treatment increased by 48.7% compared to that of the untreated specimen.

Studies of Electroless Ni-plating on Surface Properties of Carbon Fibers and Mechanical Interfacial Properties of Composites (화학환원 니켈도금 처리에 따른 탄소섬유 표면 및 복합재료의 기계적 계면 특성)

  • 박수진;장유신;이재락
    • Polymer(Korea)
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    • v.25 no.2
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    • pp.218-225
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    • 2001
  • The electroless plating of a metallic nickel on PAN-based carbon fiber surfaces was carried out to improve mechanical interfacial properties of the carbon fiber/epoxy resin composites which were unidirectionally fabricated by a prepregging method. In this work, the influence of Ni-P alloy concentration showing brittle-to-ductile transition was investigated on interlaminar shear strength (ILSS) and impact strength of the composites. The surface properties of carbon fibers were also measured by X-ray photoelectron spectroscopy (XPS). As the result, the $O_{ls}$ /$O_{ls}$ ratio or Ni and P amounts were increased with increasing electroless nickel plating time but the ILSS were not significantly improved. However, the impact properties was significantly improved in the presence of Ni-P alloy in the carbon fiber surface, resulting in an increase of the ductility of the composites.

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Mechanical Interfacial Properties of Electrospun-based Poly(ethyleneoxide) Nanofibers/Epoxy Composites (전기방사한 폴리에틸렌옥사이드 나노섬유/에폭시 복합재료의 기계적 계면특성)

  • Jeong Hyo-Jin;Lee Jae-Rock;Park Soo-Jin
    • Composites Research
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    • v.18 no.3
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    • pp.31-37
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    • 2005
  • In this work, poly(ethylene oxide) (PEO) nanofibers were fabricated by electrospinning to prepare the nanofibers-reinforced composites. And the PEO powders-impregnated composites were also prepared to compare the mechanical interfacial behaviors of the composites. Morphology and fiber diameter of PEO nanofibers were determined by SEM observation. Mechanical interfacial properties of the composites were investigated in fracture toughness $(K_{IC})$ and interlaminar shea. strength (ILSS) tests. As a result, the fiber diameter was decreased with increasing the applied voltage. And optimum condition for the fiber formation was 15 kV, resulting from increasing of jet instability at high voltage. The PEO-based nanofibers-reinforced epoxy composites showed the improvements of both $K_{IC}$ and ILSS, compared to the composites impregnated with PEO powders. These results indicated that the nanofibers had higher specific surface area and larger aspect ratio than those of the powders, which played an important role in improving the mechanical interfacial properties of the composites.