• Title, Summary, Keyword: ILSS

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Effects of High Energy Radiation on the Mechanical properties of Carbon Fiber/Dpoxy Composites (고에너지 방사선이 탄소섬유/에폭시 복합재료의 기계적 물성에 미치는 영향)

  • 박종신
    • The Korean Journal of Rheology
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    • v.3 no.1
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    • pp.22-29
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    • 1991
  • In an effort to predict the long term durability of carbon fiber/epoxy composites in a space environ-ment interlaminar shear strength (ILSS) of the composites was measured as a function of 0.5 MeV electron radiation dosage. For the ILSS measurements a notch method (ASTM D3846) was used with and without side-supports. the supports were used to prevent peeling or bending during the test. The ILSS of both T300/ 5209 longitudinal composite system increases monotonically with radiation when the test is corried out without the support the ILSS of the composites increases initially but then decreases with further radiation. It is also observed that the ILSS of the unsupported case is much lower than that of the supported case. Measurement of epoxy modulus shows that the elastic modulus increases monotonically with radiation. But the breaking strength of the epoxy decreases with radiation. Electron Spectroscopy for Chemcal Analysis shows that the oxygen contents at both the pure epoxy surface and the composite fracture surface increase with radiation dose resulting in the increase of polarity at the interfacial region. This may be a supporting evidence for the increase in the ILSS of the composites.

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The Improvement of Interlaminar Shear Strength for Low Density 2-D Carbon/Carbon Composites by Additives (첨가제에 의한 저밀도 2-D 탄소/탄소 복합재의 층간전단강도 개선)

  • 손종석;정구훈;주혁종
    • Polymer(Korea)
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    • v.24 no.6
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    • pp.845-853
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    • 2000
  • The optimum cure cycle and carbonization condition were selected by the DSC and TGA analysis and green bodies were prepared by the method of hot press molding and then carbonized up to 140$0^{\circ}C$. Additives such as graphite powder, carbon black, milled carbon fiber and carbon fiber mat, which were considered to be effective in improving the interlaminar shear strength, were also added to check their effects on the density and porosity of products. Then, their relations with mechanical properties such as ILSS and flexural strength were investigated. The composites added 9 vol% of graphite powder showed the greatest values of ILSS and flexural strength. Otherwise, in case of adding carbon black, the composites showed the slight improvement of ILSS at its contents of 3 vol% but the flexural strength was decreased. When milled carbon fiber and carbon fiber mat were added, the lack of resin and the heat shrinkage during the carbonization caused the delamination, resulting in decreasing the density, ILSS and flexural strength.

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Interlaminar Shear Strength and Impact behavior of Low Density 2-D Carbon/Carbon Composites according to Additives (첨가제에 따른 저밀도 2-D 탄소/탄소복합재의 층간전단강도 및 충격거동)

  • 손종석;정구훈;주혁종
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.88-91
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    • 2000
  • 흑연분말, 카본블랙, 탄소섬유분말을 첨가제로 한 저밀도 2-D 탄소/탄소 복합재의 밀도 및 기 기공도에 피치는 영향과 ILSS, 굽힘강도 및 충격에너지와 같은 기계적 물성과의 상관관계에 대하여 연구하였다. 흑연분말을 약 9 vol.% 첨가한 경우 가장 큰 ILSS값과 굽힘강도 및 충격에너지 흡수 거동을 나타내었는데, 특히 흑연의 함량이 증가함에 따라 puncture mode로의 충격 거동을 나타내 띠 많은 충격에너지를 흡수하였고, 인성이 상당히 증가하였다 카본블랙이 첨가된 경우에는, 약 3 vol.%에서 ILSS 값이 증가하였으나 큰 개선을 보이지 못하였으며, 굽힘강도는 감소하였다. 탄소섬유분말의 첨가량이 증가함에 따라 층간분리에 의해 밀도가 현저히 감소하여 ILSS 및 굽힘강도의 감소를 보였다.

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Inter-lamina Shear Strength of MWNT-reinforced Thin-Ply CFRP under LEO Space Environment

  • Moon, Jin Bum;Kim, Chun-Gon
    • Composites Research
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    • v.30 no.1
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    • pp.7-14
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    • 2017
  • In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum ($2.5{\times}10^{-6}torr$), atomic oxygen (AO, $9.15{\times}10^{14}atoms/cm^2{\cdot}s$), ultraviolet light (UV, 200 nm wave length) and thermal cycling ($-70{\sim}100^{\circ}C$) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature ($27^{\circ}C$), high temperature ($100^{\circ}C$) and low temperature ($-100^{\circ}C$) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thin-ply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.

Fiber Surfaces and Interlaminar Shear Strengths of Electrolytic Ni-plated Carbon Fiber/Epoxy Resin Composites (전해 니켈도금 처리에 따른 탄소섬유/에폭시 수지 복합재료의 섬유표면 및 기계적 계면전단 강도)

  • 박수진;장유신;이재락;김진석
    • Polymer(Korea)
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    • v.24 no.5
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    • pp.721-727
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    • 2000
  • The electrolytic plating of a metallic nickel on carbon fiber surfaces was carried out to improve mechanical interfacial properties of carbon fiber/epoxy resin composites. The surface characteristics of carbon fibers and the mechanical interfacial properties of final composites were characterized by X-ray photoelectron spectroscopy (XPS) and interlaminar shear strength (ILSS), respectively. It was found that the electrolytic Ni-plating conditions significantly affected the degree of adhesion at interfaces between carbon fibers and epoxy resin matrix in a composite system. Especially, the increase of O,$_{1s}$/$C_{1s}$ ratio, production of NiO groups, and formation of metallic nickel on the nickel-plated carbon fiber surfaces led to an increase of the ILSS of the composites. Also, the ILSS of the composites was greatly correlated with the $O_{1s}$/$C_{1s}$ ratio of the carbon fibers treated in this work.is work.

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Effect of Anodized Carbon Fiber Surfaces on Interfacial Adhesion of Carbon Fiber-reinforced Composites (양극산화된 탄소섬유가 복합재료의 계면결합력에 미치는 영향)

  • 박수진;김문한;최선웅;이재락
    • Polymer(Korea)
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    • v.24 no.4
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    • pp.499-504
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    • 2000
  • The effect of anodic oxidation on high strength PAN-based carbon fibers has been studied in terms of surface functionality and surface energetics of the fiber surfaces, resulting in improving the mechanical properties of composites. According to FT-IR and XPS measurements, it reveals that the oxygen functional groups on fiber surfaces induced by an anodic oxidation largely influence the surface energetics of fibers or the mechanical interfacial properties of composites, such as the interlaminar shear strength (ILSS) of composites. According to the contact angle measurements based on the wicking rate of a test liquid, it is observed that anodic oxidation does lead to an increase in surface free energy of the carbon fibers, mainly due to the increase of its specific (or polar) component. From the surface energetic point of view, it is found that good wetting plays an important role in improving the degree of adhesion at interfaces between fiber and epoxy resin matrix of the resulting composites. Also, a direct linear relationship is shown between 01s/01s ratio and ILSS or between specific component and ILSS of the composites for this system.

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Effects of Increase in Ratio of Phenolic Hydroxyl Function on Carbon Fiber Surfaces by Anodic Oxidation on Mechanical Interfacial Bonding of Carbon Fibers-reinforced Epoxy Matrix Composites (양극산화 처리에 따른 탄소섬유 표면의 페놀릭 하이드록실 관능기 비율의 증가가 에폭시기지 복합재료의 기계적 계면결합 특성에 미치는 영향)

  • Kim, Dong-Kyu;Kim, Kwan-Woo;Han, Woong;Song, Bhumkeun;Oh, Sang-Yub;Bang, Yun Hyuk;Kim, Byung-Joo
    • Applied Chemistry for Engineering
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    • v.27 no.5
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    • pp.472-477
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    • 2016
  • We studied the effects of anodic oxidation treatments of carbon fibers on interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites with various current densities. The surface of treated carbon fibers was characterized by atomic force microscope (AFM), field emission-scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The interlaminar shear strength (ILSS) of the composites was determined by a short beam shear test. This result showed that both the roughness and oxygen group of the carbon fibers surface increased in proportion to the current density. After anodic-oxidation-treated, the ILSS also increased as a function of the current density. In addition, the proportional relationship between ILSS and phenolic hydroxyl group was confirmed. The ILSS of the CF-2.0 sample increased by 4% compared to that of the CF-AS sample, because the anodic oxidation treatment increased the oxygen group and roughness on the carbon fibers surface, which leading to the improvement of the interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites. Among these, the phenolic hydroxyl group which has the proportional relationship with ILSS is found to be the most important factor for improving the interfacial adhesion of the carbon fibers-reinforced epoxy matrix composites.

A Degradation Characteristic of FRP Rebars Attacked by Combined Environmental Factors (복합환경인자에 의한 FRP 보강근의 성능저하 특성)

  • Oh, Hong Seob;Moon, Do Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.3
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    • pp.1-10
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    • 2012
  • In spite of high resistant to corrosion and its strength, over the last two decades, concerns still remain about the durability of FRP materials under severe environmental and thermal exposures. In this paper, authors experimentally examine the combined degradation by thermal and chemical attacks in heterogeneous FRP rebar be made up with various fibers and resins. Five types of Carbon, Glass and Hybrid FRP rebars had manufactured by different process and surface patterns are adopted for the experiments such as weight change, interlaminar shear strength, SEM and FT-IR analysis. FRP specimens were immersed in alkaline or distilled solution up to 150 days and then thermal exposed on 60, 100, 150 and $300^{\circ}C$ for 30 minutes. From the test results, the degradation of FRP bars are influnced by the resin type and manufacturing process as well as the fiber, and ILSS of exposed FRP bar in solutions is slightly increased in initial stage and then decresed with the passing of immersed time. But, in this test, it is observed that the discrepancy of ILSS between degraded by alkaline solution and distilled water is negligible value.

Interlaminar Shear Strength of Carbon Fiber Epoxy Composite with Nickel Film (니켈 박막 첨가에 따른 탄소섬유 에폭시 복합재료의 층간 계면 특성)

  • Lee, Min-Kyung
    • Composites Research
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    • v.28 no.3
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    • pp.94-98
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    • 2015
  • This paper reports the effects of nickel film interleaves on the interlaminar shear strength(ILSS) of carbon fiber reinforced epoxy composites(CFRPs). A nickel thin film was deposited onto the prepreg by radio frequency(RF) sputtering at room temperature. The ILSS of the nickel film interleaved hybrid composites was increased compared to that of the composites without interleaves. To understand the mechanism of enhancement of the ILSS, the fracture surface of the tested specimens was examined by scanning electron microscopy(SEM). The metal interleaves were acted as a reinforcement for the matrix rich interface and the shear property of their composites improved by enhancing the resistance to matrix cracking.

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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