• Title, Summary, Keyword: epoxy

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Effects of oil absorption on the wear behaviors of carbon/epoxy woven composites

  • Lee, Jae-H.;Lee, Jae-S.;Rhee, Kyong-Y.
    • Carbon letters
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    • v.12 no.4
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    • pp.249-251
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    • 2011
  • Carbon/epoxy woven composites are prominent wear-resistant materials due to the strength, stiffness, and thermal conductivity of carbon fabric. In this study, the effect of oilabsorption on the wear behaviors of carbon/epoxy woven composites was investigated. Wear tests were performed on dry and fully oil-absorbed carbon/epoxy woven composites. The worn surfaces of the test specimens were examined via scanning electron microscopy to investigate the wear mechanisms of oil-absorbed carbon/epoxy woven composites. It was found that the oil absorption rate was 0.14% when the carbon/epoxy woven composites were fully saturated. In addition, the wear properties of the carbon/epoxy woven composites were found to be affected by oilabsorption. Specifically, the friction coefficients of dry and oil-absorbed carbon/epoxy woven composites were 0.25-0.30 and 0.55-0.6, respectively. The wear loss of the oilabsorbed carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$, while that of the dry carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$. SEM results revealed that the higher friction coefficient and wear loss of the oil-absorbed carbon/epoxy woven composites can be attributed to the existence of broken and randomly dispersed fibers due to the weak adhesion forces between the carbon fibers and the epoxy matrix.

The Study of Water Stability of MDF Cement Composite by Addition of Epoxy Resin and Manufacturing Process (Epoxy Resin 첨가 및 제조공정에 따른 MDF 시멘트 복합재료의 수분안정성 연구)

  • 노준석;김태진;박춘근;최상홀
    • Journal of the Korean Ceramic Society
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    • v.35 no.4
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    • pp.371-377
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    • 1998
  • The effect of epoxy resin on the water stability of HAC/PVA based MDF cement composite were stu-died through the three different forming methods calendering extruding and warm pressing. In prexing step the epoxy resin was added in 5-15wt% of cement weight. The 3-point flexural strength of each dry and wet specimen which were immersed in water during 3. 7, 14 days was estmated and the mi-crostructural change of epoxy resin-added MDF cement composite due to water immersion was charac-terized by scanning electron microscopy. As the addition amount of epoxy resin the im-provement of water stability of MDF cement composite was achieved in most case. Especially through the warm press forming method the effectiveness of epoxy resin addition to the water stability was enhanced. When the epoxy resin was added by 5wt% to 7wt% the optimum flexural strength and water stability

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An Estimation of the Long-Term Properties of Epoxy Used for Reinforcing Surface in Concrete (콘크리트 표면강화 에폭시의 장기특성 평가)

  • 김성욱;김도겸;이장화;김근경;김상조
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.183-186
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    • 1999
  • Up to date, it is difficult to estimate the consistence of properties on the epoxy liner in service time because an estimation of the long term environment-deterioration with aging has not been processed. In the study, the estimation on epoxy liner is carried by the physical test 7 rounds. There are the elongation the and the crack bridging test in the part of physical tests. An elongation test is carried out with epoxy membrane and a crack bridging test is carried out with specimen painted epoxy on concrete. The subjects of test and estimation are a containment quality system and a fibre-glass reinforced system. The materials of these systems are a Robber added Epoxy, a Silica added Epoxy, and a Fiber reinforced Epoxy. Ensuring the test data, properties of epoxy liner was estimated and the change of properties was predicted on epoxy liners.

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Stochastic Estimation of Acoustic Impedance of Glass-Reinforced Epoxy Coating

  • Kim, Nohyu;Nah, Hwan-Seon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.2
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    • pp.119-127
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    • 2014
  • An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

Improved mechanical and electromagnetic interference shielding properties of epoxy composites through the introduction of oxyfluorinated multiwalled carbon nanotubes

  • Lee, Kyeong Min;Lee, Si-Eun;Lee, Young-Seak
    • Journal of Industrial and Engineering Chemistry
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    • v.56
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    • pp.435-442
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    • 2017
  • To improve the mechanical properties of epoxy composites, multiwalled carbon nanotubes (MWCNTs) were oxyfluorinated and used as reinforcement in an epoxy matrix. A comparison of various oxyfluorinated MWCNTs and neat epoxy revealed that the tensile strength of the epoxy composites with oxyfluorinated MWCNTs increased by approximately 24%. The maximum impact strength of these epoxy composites were improved by 43% compared to that of neat epoxy. The electromagnetic interference shielding efficiency (EMI-SE) of the epoxy composites with oxyfluorinated MWCNTs was enhanced with the increasing oxygen concentration during the oxyfluorination. The composites resulted in the maximum EMI-SE increase of 18% compared to that of the neat epoxy. These results were attributed to the oxyfluorination effects of MWCNTs, which form an interface with stronger adhesion as a consequence of the presence of oxygen and fluorine functional groups on the surface of the MWCNTs.

Mechanical and thermal properties of MWCNT-reinforced epoxy nanocomposites by vacuum assisted resin transfer molding

  • Lee, Si-Eun;Cho, Seho;Lee, Young-Seak
    • Carbon letters
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    • v.15 no.1
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    • pp.32-37
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    • 2014
  • Multi-walled carbon nanotube (MWCNT)/epoxy composites are prepared by a vacuum assisted resin transfer molding (VARTM) method. The mechanical properties, fracture surface morphologies, and thermal stabilities of these nanocomposites are evaluated for epoxy resins with various amounts of MWCNTs. Composites consisting of different amounts of MWCNTs displayed an increase of the work of adhesion between the MWCNTs and the matrix, which improved both the tensile and impact strengths of the composites. The tensile and impact strengths of the MWCNT/epoxy composite improved by 59 and 562% with 0.3 phr of MWCNTs, respectively, compared to the epoxy composite without MWCNTs. Thermal stability of the 0.3 phr MWCNT/epoxy composite increased compared to other epoxy composites with MWCNTs. The enhancement of the mechanical and thermal properties of the MWCNT/epoxy nanocomposites is attributed to improved dispersibility and strong interfacial interaction between the MWCNTs and the epoxy in the composites prepared by VARTM.

Synthesis of Epoxy Functional Siloxane and its Effect on Thermal Stress

  • Hyun, Dae-Sup;Jeong, Noh-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.26 no.4
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    • pp.379-384
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    • 2009
  • Epoxy resin based encapsulants are widely used in semiconductor packaging applications. Epoxy resin based encapsulants are often subject to crack or delamination during the reliability test due to the thermal stress caused by high modulus nature of epoxy resins. Epoxy functional siloxanes are often added into epoxy resin to reduce the modulus so that the thermal stress can be reduced. Epoxy functional siloxanes, additives for reduced modulus, were synthesized and added into the curable epoxy resins. The modulus and the coefficient of thermal expansion (CTE) were also measured to investigate the thermal stress and to see whether the epoxy functional siloxane adversely affects the CTE or not. As a result, around 26% to 72% of thermal stress reduction was observed with no adverse effect on CTE.

Properties of Epoxy Modified PVC-sol Sealants (에폭시가 함유된 PVC졸 실란트의 물성)

  • Lee, Seung-Jin;Kim, Hyun-Kyo;Park, Hwan-Man;Cho, Won-Jei;Ha, Chang-Sik
    • Elastomers and Composites
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    • v.34 no.3
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    • pp.199-211
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    • 1999
  • In this work, the effects of the addition of epoxy on the properties of PVC-sol sealants were investigated. PVC-sol was plasticized with dioctyl phthalates(DOP). Two kinds of epoxy resins having different epoxy equivalent weight (E.E.W.) were used. It was found that the properties of the PVC-sol sealants were significantly affected by the contents and types of the added epoxy resins. The viscosity behaviors of the epoxy-modified sealants, in the case of epoxy A addition, the viscosity was decreased with increasing the epoxy contents, but In the case of $CaCO_3$ addition, the viscosity was increased with increasing the $CaCO_3$ contents. The viscosity of epoxy modified sealants aged at $45^{\circ}C$ waterbath was decreased with increasing epoxy contents, since the epoxy acted on the sealants as a stabilizer. The thermal stability of the PVC-sol sealants was slightly improved by adding epoxy. The tensile strength and elongation of sealants modified with epoxy A(two functionalities of epoxy) were increased with increasing the epoxy contents up to a certain epoxy contents but was decreased with further increasing the epoxy contents. In the case of $CaCO_3$ addition, the tensile strength of sealants were decreased with increasing the $CaCO_3$ contents. In view of the electrical properties, such as tan ${\delta}$($0.1{\pm}0.04$) and ${\epsilon}_r$($0.5{\pm}0.04$), it was found that the epoxy modified sealants were as good as insulators.

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The Toughness of Polyurethane and Epoxy Resins IPNs (폴리우레탄-에폭시 IPNs의 강인성)

  • Kim, Jong Seok;Hong, Suk Pyo
    • Applied Chemistry for Engineering
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    • v.9 no.3
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    • pp.445-450
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    • 1998
  • Interpenetrating polymer networks(IPNs) were prepared from castor oil-type polyurethanes(PUs) and epoxy resin. Two types of PU were prepared by using polypropylene ether glycol(PPG) as a chain extending agent and caster oil(CO) as a crosslinking agent. COPU/epoxy simultaneous interpenetrating polymer networks(SINs) based on CO had a better compatibility over the all composition than PPGPU/epoxy SINs based on PPG. The flexural strength of all PPGPU/epoxy SINs was decreased with decreasing entanglement of networks. COPU/epoxy SINs showed the higher fracture toughness and mechanial properties than the PPGPU/epoxy SINs. Fracture surfaces of all of the SINs showed the localized shear deformation and crack deflection rather than generation of stress whitening associated with the cavitation.

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Cure Properties of Isocyanurate Type Epoxy Resin Systems for FO-WLP (Fan Out-Wafer Level Package) Next Generation Semiconductor Packaging Materials (FO-WLP (Fan Out-Wafer Level Package) 차세대 반도체 Packaging용 Isocyanurate Type Epoxy Resin System의 경화특성연구)

  • Kim, Whan Gun
    • Journal of the Semiconductor & Display Technology
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    • v.18 no.1
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    • pp.65-69
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    • 2019
  • The cure properties of ethoxysilyl diglycidyl isocyanurate(Ethoxysilyl-DGIC) and ethylsilyl diglycidyl isocyanurate (Ethylsilyl-DGIC) epoxy resin systems with a phenol novolac hardener were investigated for anticipating fan out-wafer level package(FO-WLP) applications, comparing with ethoxysilyl diglycidyl ether of bisphenol-A(Ethoxysilyl-DGEBA) epoxy resin systems. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, and the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The isocyanurate type epoxy resin systems represented the higher cure conversion rates comparing with bisphenol-A type epoxy resin systems. The Ethoxysilyl-DGIC epoxy resin system showed the highest cure conversion rates than Ethylsilyl-DGIC and Ethoxysilyl-DGEBA epoxy resin systems. It can be figured out by kinetic parameter analysis that the highest conversion rates of Ethoxysilyl-DGIC epoxy resin system are caused by higher collision frequency factor. However, the cure conversion rate increases of the Ethylsilyl-DGEBA comparing with Ethoxysilyl-DGEBA are due to the lower activation energy of Ethylsilyl-DGIC. These higher cure conversion rates in the isocyanurate type epoxy resin systems could be explained by the improvements of reaction molecule movements according to the compact structure of isocyanurate epoxy resin.