• Title/Summary/Keyword: 탄소/에폭시 튜브

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Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission (전기적-미세역학시험법과 음향방출을 이용한 단일 탄소섬유/탄소나노튜브-에폭시 나노복합재료의 자체-감지능)

  • Park, Joung-Man;Jang, Jung-Hoon;Wang, Zuo-Jia;Kwon, Dong-Jun;Park, Jong-Kyu;Lee, Woo-Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.5
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    • pp.411-422
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    • 2010
  • Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT -epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to micro failure at the interfaces by added CNTs.

Effect of Fluorination of Carbon Nanotubes on Physico-chemical and EMI Shielding Properties of Polymer Composites (고분자 복합재의 물리화학적 및 전자파차폐 특성에 미치는 탄소나노튜브의 불소화 영향)

  • Lee, Si-Eun;Kim, Doyoung;Lee, Man Young;Lee, Min-Kyung;Jeong, Euigyung;Lee, Young-Seak
    • Polymer(Korea)
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    • v.39 no.1
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    • pp.114-121
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    • 2015
  • Mutli-walled carbon nanotubes (MWCNTs) were surface-modified by a hydrofluoric acid solution to remove impurities and improve interfacial bonding and dispersion of nanotubes in an epoxy matrix. The crystallinity on the surface of treated MWCNTs was investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties were characterized by tensile test, and the enhancement of mechanical properties of the modified MWCNTs/epoxy composites was indicated by a 33% increase in tensile strength. The electromagnetic interference shielding effectiveness (EMI-SE) of modified MWCNTs/epoxy composites was improved with an increase in concentration of hydrofluoric solution, and EMI-SE showed the maximum increase with 25% HF. However, mechanical and EMI-SE properties didn't show further increase with over 50% HF concentration because the properties of MWCNTs were influenced by degradation of crystallinity and intrinsic properties of MWCNTs. The mechanical and electrical property enhancements of the polymer composites are attributed to the modification of MWCNTs which improve crystallinity of MWCNTs and dispersion in the epoxy resin.

Influence of Alkylation on Interface and Thermal Conductivity of Multi-walled Carbon Nanotubes-reinforced Epoxy Resin (알킬화가 다중벽탄소나노튜브로 강인화된 에폭시수지의 계면 및 열전도도에 미치는 영향)

  • Heo, Gun-Young;Rhee, Kyong-Yop;Park, Soo-Jin
    • Polymer(Korea)
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    • v.35 no.6
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    • pp.548-552
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    • 2011
  • Two functionalization methods, i.e., acid treatment and chemical amidation were performed to prepare the functionalized multi-walled carbon nanotubes (MWCNT), and the properties of epoxy/functionalized MWCNT composites were investigated and compared. Fourier transform infrared spectroscopy (FTIR) was used to confirm the surface functionality of the MWCNT obtained by the functionalization methods. The effects of the MWCNT functionalization on the interface and thermal conductivity were studied by zeta potential analyzer, scanning electron microscope and thermal conductivity analyzer. From these results, it was confirmed that the thermal conductivity of the epoxy/MWCNT composites could be increased by grafting with dodecylamine. This could be interpreted by relatively strong dispersion forces of the grafting MWCNT with dodecylamine in DGEBF epoxy resin. These results were in good agreement with the results that the zeta potential value of the grafting MWCNT with dodecylamine has a higher negative value than that of MWCNT with acid treatment.

Measurement of Mechanical Property and Thermal Expansion Coefficient of Carbon-Nanotube-Reinforced Epoxy Composites (탄소나노튜브로 강화된 에폭시 복합재료의 기계적 물성과 열팽창 계수 측정)

  • Ku, Min Ye;Kim, Jung Hyun;Kang, Hee Yong;Lee, Gyo Woo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.5
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    • pp.657-664
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    • 2013
  • By using shear mixing and ultrasonication, we fabricated specimens of well-dispersed multi-walled carbon nanotube composites. To confirm the proper dispersion of the filler, we used scanning electron microscopy images for quantitative evaluation and a tensile test for qualitative assessment. Furthermore, the coefficients of thermal expansion of several specimens having different filler contents were calculated from the measured thermal strains and temperatures of the specimens. Based on the microscopy images of the well-dispersed fillers and the small deviations in the measurements of the tensile strength and stiffness, we confirmed the proper dispersion of nanotubes in the epoxy. As the filler contents were increased, the values of tensile strength increased from 58.33 to 68.81 MPa, and those of stiffness increased from 2.93 to 3.27 GPa. At the same time, the coefficients of thermal expansion decreased. This implies better thermal stability of the specimen.

A Study on Tensile Properties of Multi-Welled Carbon Nanotube/Epoxy Composites (다중벽 탄소나노튜브/에폭시 복합재료의 인장 물성에 관한 연구)

  • Lee Sang-Eui;Lee Won-Jun;Kim Chun-Gon
    • Composites Research
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    • v.17 no.6
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    • pp.1-7
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    • 2004
  • The studies of particulate reinforced composites have been conducted for many years. The nanocomposites to be studied vigorously in recent years are one of them. We fabricated and studied multi-walled carbon nanotube(MWNT)/epoxy composites which may be useful as matrix for continuous fiber-reinforced composites. We investigated tensile properties of MWNT/epoxy composites as a function of MWNT concentration, which were prepared by the fabrication method established in this study. Tensile stiffness and strength increased 19% at 0.5 wt% and 12% at 0.2 wt%, respectively. We observed the reaggregation phenomenon of MWNTS during curing, which should be controlled to obtain higher tensile properties.

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.

Mechanical and Thermal Properties of Epoxy Composites Reinforced Fluorinated Illite and Carbon Nanotube (불소화 일라이트 및 탄소나노튜브 강화 에폭시 복합재의 기계적 및 열적 특성)

  • Lee, Kyeong Min;Lee, Si-Eun;Kim, Min Il;Kim, Hyeong Gi;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.27 no.3
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    • pp.285-290
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    • 2016
  • To improve properties of epoxy composites, surfaces of the illite and carbon nanotube (CNT) were treated by fluorine gas. The fluorinated illite and CNT were then characterized by X-ray photoelectron microscopy (XPS) and the mechanical and thermal properties of their composites were evaluated. The tensile and impact strengths and thermal stability of the composites increased upto about 59%, 18% and 124%, respectively compared to those of the neat epoxy. Improvements of mechanical and thermal properties in the composites were attributed that the fluorination of illite and carbon nanotube helps to enhance the dispersion in epoxy resin and interfacial interaction between them.

Study on the Axial Crushing Behaviors of UD Kevlar/Epoxy and Carbon-Kevlar/Epoxy Composite Tubes (단방향 케블라/에폭시, 탄소-케블라/에폭시 복합재 튜브의 축방향 압괴 거동에 대한 연구)

  • Kim, Hyung-Uk;Kim, Jung-Seok;Jung, Hyun-Seung;Yoon, Hyuk-Jin;Kwon, Tae-Soo
    • Journal of the Korean Society for Railway
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    • v.13 no.3
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    • pp.271-277
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    • 2010
  • In this paper, a numerical model for a Kevlar/Epoxy and Carbon-Kevlar/Epoxy tube used as an energy absorbing component has been developed and then results have been verified through experiment. The 2D shell element and Chang-Chang failure criterion of LS-DYNA that is commercial explicit FE code was used. Mechanical material properties for the model were obtained by material testing in advance. The numerical results were compared with quasi-static test results under axial compressive loading at 10mm/min. From the results, in the case of the Kevlar/Epoxy tube, load-crushed displacement curves were very close to the experiments and SEA (specific energy absorption) shows a good agreement with experimental one within less than 6%. However, the Carbon-Kevlar/Epoxy tube shows some differences with the experimental results.

Nondestructive Damage Sensitivity of Carbon Nanotube and Nanofiber/Epoxy Composites using Electro- Micromechanical Technique and Acoustic Emission (전기적-미세역학 시험법과 음향 방출을 이용한 탄소 나노튜브와 나노섬유 강화 에폭시 복합재료의 비파괴 손상 감지능)

  • 김대식;박종만;김태욱
    • Polymer(Korea)
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    • v.28 no.4
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    • pp.285-290
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    • 2004
  • Nondestructive damage sensitivity of carbon nanotube(CNT) and nanofiber (CNF)/epoxy composites with their adding contents was investigated using electro-micromechanical technique. Carbon black (CB) was used only for the comparison with CNT and CNF. The fracture of carbon fiber was detected by acoustic emission (AE), which was correlated to the change in electrical resistance, ΔR under double-matrix composites (DMC) test. Stress sensing on carbon nanocomposites was performed by electro-pullout test under uniform cyclic loading. At the same volume fraction, the damage sensitivity for fiber fracture, matrix deformation and stress sensing were highest for CNT/epoxy composite, whereas for CB/epoxy composite they were the lowest among three carbon nanomaterials (CNMs). Damage sensitivity was correlated with morphological observation of carbon nanocomposites. Homogeneous dispersion among CNMs could be keying parameters for better damage monitoring. In this study, damage sensing of carbon nanocomposites could be evaluated well nondestructively by the electrical resistance measurement with AE.

Interfacial Properties and Sensing of Carbon Nanofiber/Tube and Electrospun Nanofiber/Epoxy Composites Using Electrical Resistance Measurement and Micromechanical Technique (전기저항측정 및 미세역학시험법을 이용한 탄소나노섬유/튜브 및 전기방사된 나노섬유/에폭시 복합재료의 계면특성 및 감지능 연구)

  • Jung Jin-Gyu;Kim Sung-Ju;Park Joung-Man
    • Composites Research
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    • v.18 no.4
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    • pp.21-26
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    • 2005
  • Nondestructive damage sensing and load transfer mechanisms of carbon nanotube (CNT) and nanofiber (CNF)/epoxy composites have been investigated by using electro-micromechanical technique. The electrospun PVDF nanofibers were also prepared as a piezoelectric sensor. The electro-micromechanical techniques were applied to evaluate sensing response of carbon nanocomposites by measuring electrical resistance under an uniform cyclic loading. Composites with higher volume content of CNT showed significantly higher tensile properties than neat and low volume$\%$ CNT composites. CNT composites showed humidity sensing within limited temperature range. CNT composites with smaller aspect ratio showed higher apparent modulus due to high volume content in case of shorter aspect ratio. Thermal treated electrospun PVDF nanofiber showed higher mechanical properties than the untreated case due to crystallinity increase, whereas load sensing decreased in heat treated case. Electrospun PVDF nanofiber web also showed sensing effect on humidity and temperature as well as stress transferring. Nanocomposites and electrospun PVDF nanofiber web can be applicable for sensing application.