• Title/Summary/Keyword: Epoxy composites

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Nondestructive Damage Sensitivity for Functionalized Carbon Nanotube and Nanofiber/Epoxy Composites Using Electrical Resistance Measurement and Acoustic Emission (전기저항 측정과 음향방출을 이용한 표면 처리된 탄소 나노튜브와 나노 섬유 강화 에폭시 복합재료의 비파괴적 손상 감지능)

  • Kim, Dae-Sik;Park, Joung-Man;Kim, Tae-Wook
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.42-45
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    • 2003
  • Nondestructive damage sensing and mechanical properties for acid-treated carbon nanotube (CNT) and nanofiber (CNF)/epoxy composites were investigated using electro-micromechanical technique and acoustic emission (AE). Carbon black (CB) was used to compare to CNT and CNF. The results were compared to the untreated case. The fracture of carbon fiber was detected by nondestructive acoustic emission (AE) relating to electrical resistivity under double-matrix composites test. Sensing for fiber tension was performed by electro-pullout test under uniform cyclic strain. The sensitivity for fiber damage such as fiber fracture and fiber tension was the highest for CNT/epoxy composites. Reinforcing effect of CNT obtained from apparent modulus measurement was the highest in the same content. For surface treatment case, the damage sensitivity and reinforcing effect were higher than those of the untreated case. The results obtained from sensing fiber damage were correlated with the morphological observation of nano-scale structure using FE-SEM. The information on fiber damage and matrix deformation and reinforcing effect of carbon nanocomposites could be obtained from electrical resistivity measurement as a new concept of nondestructive evaluation.

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Nondestructive Damage Sensitivity of Carbon Nanotube and Nanofiber/Epoxy Composites Using Electro-Micromechanical Technique and Acoustic Emission (Electro-Micromechanical 시험법과 음향방출을 이용한 탄소 나노튜브와 나노섬유 강화 에폭시 복합재료의 비파괴적 손상 감지능)

  • Kim, Dae-Sik;Park, Joung-Man;Lee, Jae-Rock;Kim, Tae-Wook
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.117-120
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    • 2003
  • Electro-micromechanical techniques were applied using four-probe method for carbon nanotube (CNT) or nanofiber (CNF)/epoxy composites with their content. Carbon black (CB) was used to compare with CNT and CNF. The fracture of carbon fiber was detected by nondestructive acoustic emission (AE) relating to electrical resistivity for double-matrix composites test. Sensing for fiber tension was performed by electro-pullout test under uniform cyclic strain. The sensitivity for fiber damage such as fiber fracture and fiber tension was the highest for CNT/epoxy composites, and in CB case they were the lowest compared with CNT and CNF. Reinforcing effect of CNT obtained from apparent modulus measurement was the highest in the same content. The results obtained from sensing fiber damage were correlated with the morphological observation of nano-scale structure using FE-SEM. The information on fiber damage and matrix deformation and reinforcing effect of carbon nanocomposites could be obtained from electrical resistivity measurement as a new concept of nondestructive evaluation.

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A Study on Permittivity of Multi-walled Carbon nanotube/Epoxy Composites (다중벽 탄소나노튜브/에폭시 복합재료의 유전율에 관한 연구)

  • 이상의;박기연;김천곤;한재흥
    • Composites Research
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    • v.17 no.3
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    • pp.38-44
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    • 2004
  • The electromagnetic interference (EMI) shielding is very essential for commercial and military purposes. We fabricated multi-walled carbon nanotube (MWNT)/epoxy composites and studied the electromagnetic characteristics of the composites before we study the characteristics of MWNT-added glass fiber-reinforced composites. After setting up the fabrication process, we measured the permittivity of MWNT/epoxy composites with process variables and MWNT concentrations in X-band (8.2GHz~12.4GHz). We also observed re-aggregation phenomenon of MWNTs and investigated its effect on the permittivity. The permittivity of the composites was influenced by the degree of dispersion of MWNTs and increased almost linearly as MWNT concentration increases.

Friction and Wear Characteristics of Silica/Epoxy Composites for various Particle Size (입자지름의 변화에 따른 실리카 복합재료의 마찰 및 마모 특성)

  • Koh, Sung-Wi;Kim, Hyung-Jin;Kim, Kae-Dong;Kim, Chang-Soo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.141-144
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    • 2006
  • In this study, the friction and wear characteristics of pure epoxy and silica-filled epoxy resin composites with average silica particle diameter of $6-33{\mu}m$ were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials against SiC abrasive paper were determined experimentally. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. silica filled epoxy.

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The Recovery of Carbon Fiber from Carbon Fiber Reinforced Epoxy Composites for Train Body (철도차량용 폐 복합소재에서의 탄소섬유 회수)

  • Lee, Suk-Ho;Lee, Cheul-Kyu;Kim, Yong-Ki;Kim, Jung-Seok;Ju, Chang-Sik
    • Proceedings of the KSR Conference
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    • pp.406-415
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    • 2008
  • Recently, the amount of thermosetting plastic wastes have increased with the production of reinforced plastic composites and causes serious environmental problems. The epoxy composites, one of the versatile thermosetting plastics with excellent properties, cannot be melted down and remolded as what is done in the thermoplastic industry. In this research, a series of experiments that recovers carbon fibers from carbon fiber reinforced epoxy composites for train body was performed. We experimentally examined various decomposition processes and compared their decomposition efficiencies and mechanical property of recovered carbon fibers. For the prevention of tangle of recovered carbon fibers, each composites specimen was fixed with a Teflon supporter and no mechanical mixing was applied. Decomposition products were analyzed by scanning electron microscope (SEM), gas chromatography mass spectrometer (GC-MS), and universal testing machine (UTM). Carbon fibers could be completely recovered from decomposition process using nitric acid aqueous solution, liquid-phase thermal cracking and pyrolysis. The tensile strength losses of the recovered carbon fibers were less than 4%.

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The variations of tracking resistance of outdoor Epoxy composites due to complex degradation (복합열화로 인한 옥외용 에폭시수지의 내트래킹성 변화)

  • Kim, T.Y.;Kim, K.M.;Lee, D.J.;Son, I.H.;Ka, C.H.;Kim, J.H.
    • Proceedings of the KIEE Conference
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    • pp.1614-1616
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    • 1999
  • Epoxy resin has been used as matrix resin of advanced composites owing to ideally suitable properties and inherent physical and chemical properties for electrical and electronic insulation. In this paper, in order to evaluate the performance of epoxy composites for out door insulation, variations of tracking resistance were investigated on the complex ageing parameter. Also, IPN methods were introduced in order to improve performance for out door use. As a result, it was confirmed that tracking resistance were degraded with complex ageing parameters. But, it was confirmed that specimen of IPN structure have the better tracking resistance properties than SIN structure by moisture absorption aging.

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An Estimation of Breakdown Time of the Epoxy Composites according to Filler and Silane Treatment (충진제와 실란처리에 따른 에폭시 복합체의 파괴시간 예측)

  • Shin, Cheol-Gi
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.9
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    • pp.793-797
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    • 2007
  • In this paper, the long time breakdown characteristic of the epoxy composite, which is widely used in the insulation system for high voltage application, was estimated with Weibull distribution. In the procedure of the estimation, the short time breakdown characteristics for the epoxy composite specimens, which were made with the variation of hardener and/or filler, were tested firstly. Then the long time voltage-to-time test was implemented. Finally, the long time breakdown voltage of each specimen was estimated with the parameters obtained from the statistical treatment with Weibull distribution. Base on the results, it has been found that the optimal weight ratio of epoxy resin/hardener/filler that has the excellent long time breakdown characteristic was 100/100/65. It was due to the silane treatment which relieves the electric field at the interface between filler and epoxy.

Dynamic Strength Variation of Glass Epoxy Composites with respect to Strain Rates (변형률 속도에 따른 유리섬유 에폭시 복합재료의 동적 강도 변화)

  • 임태성;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.83-88
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    • 2001
  • In this study, the tensile and compressive tests of glass fiber epoxy composites were performed to measure the strength variation with respect to strain rates of 1-200 $\textrm{sec}^{-1}$. In addition, tensile and compressive tests of 50-200 $\textrm{sec}^{-1}$ strain rates were conducted at a low temperature ($-60^{\circ}C$) to investigate the effects of temperature on the strength variation. From the test results, it was found that the tensile and compressive strengths increased about 100% and 70%, respectively, at the strain rates of 10-100 $\textrm{sec}^{-1}$ compared to the quasi-static strengths while the strengths were little affected by the environmental temperature variation.

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Cutting(Milling) Characteristics of Carbon Fiber/Epoxy Composites (탄소섬유 에폭시 복합재료의 절삭(밀링) 특성)

  • 김기수;이대길;곽윤근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.37-42
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    • 1990
  • Carbon fiber epoxy composite materials are widely used in the structures of aircrafts, robots and other machines because of their high specific stiffness, high specific strength and damping. In order for the composite materials to be used in the robot structure or machine element, bearing mounting and joining surfaces must be provided, which require accurate machining. In this paper, the machinability and tool wear characteristics of the milling operation of the carbon fiber epoxy composite materials were experimentally measured. The tool wear mechanism and the Taylor tool wear constants were determined. Also, the surface roughness of milling operation was measured w.r.t. cutting speed and feed.