• Title/Summary/Keyword: Curing Reaction

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Curing and Rheological Behavior of Epoxy Resin Compositions for Underfill (언더필용 에폭시 수지 조성물의 경화 및 유변학적 거동)

  • Kim, Yoon-Jin;Park, Min;Kim, Jun-Kyung;Kim, Jin-Mo;Yoon, Ho-Gyu
    • Elastomers and Composites
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    • v.38 no.3
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    • pp.213-226
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    • 2003
  • The cure and rheological behavior of diglycidyl ether of bisphenol F/nadic methyl anhydride resin system with the kinds of imidazole were studied using a differential scanning calorimeter (DSC) and a rotational rheometer. The isothermal traces were employed to analyze cure reaction. The DGEBF/ anhydride conversion profiles showed autocatalyzed reaction characterized by maximum conversion rate at $20{\sim}40 %$ of the reaction. The rate constants ($k_1,\;k_2$) showed temperature dependance, but reaction order did not. The reaction order (m+n) was calculated to be close to 3. There are two reaction mechanisms with the kinds oi catalyst. The gel time was determined by using G'-G" crossover method, and the activation energy was obtained from this results. From measurement of rheological properties it was found that the logarithmic 1:elation time of fused silica filled DBEBF epoxy compounds linearly increased with the content of filler and decreased with temperature. The highly filled epoxy compounds showed typical pseudoplastic behavior, and the viscosity of those decreased with increasing maximum packing ratio.

Effect of the Binder Content on the Recycling of Scrap Waste Tires (폐타이어 재활용에 있어서 Binder양이 미치는 영향)

  • Kim, Jin-Kuk;Cho, Ha-Na;Lee, Soo-Koo
    • Elastomers and Composites
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    • v.29 no.5
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    • pp.431-435
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    • 1994
  • For recycling of the waste tires, polyurethane binder mixed with the scrapped rubber powders which obtained from tread part of waste tire. This study covered the effect of the binder contents on the mechanical properties of the blend. We also studied the change of the properties after aging on properties compared with those of before aging. The curing reaction of the binder was also investigated in this study. We obtained conclusions the suitable binder content was 15phr in this system.

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Modeling of the Setting Characteristics of Early-age Concrete (초기재령 콘크리트의 응결특성 모델링)

  • 조호진;송하원;변근주
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.391-396
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    • 2002
  • The so called setting is defined as the onset of rigidity in fresh concrete. In the analysis of the early-age concrete behavior, we consider fresh concrete as a structural element immediately after mixing. But for the activation of real structural behavior of fresh concrete, it takes some time after the beginning of hydration reaction. So, the very early age deformations due to hydration heat and shrinkage which occur before the setting do not produce restraint stresses. In this paper, we propose a setting characteristic model based on the so called percolation theory. From the analysis using the model, the influence of curing temperature is investigated and analytical results are compared with experimental results. From the comparison, the validity of proposed model is verified. This model is also applied to evaluate stress development in a temperature-stress test machine (TSTM) specimen and then the effect of setting time on the stress development is discussed.

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The Characteristics of Solidification and Leachability of Lead Sludge (납슬러지 고형화 및 용출 특성)

  • 연익준;주소영;김광렬
    • Journal of environmental and Sanitary engineering
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    • v.14 no.3
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    • pp.22-30
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    • 1999
  • This study was carried out to examine the compressive strength characteristics of solids solidified with the lead sludge with mixture of cement and fly ashes as additive. And the additives are commercial fly ash and ESP(Electrostatic precipitator) fly ash. The compressive strength of solidified lead sludge solid was increased by adding fly ash up to 46~62%, which was the results of pozzolanic reaction. When replaced the cement with 10%of commercial fly ash, the solid showed the highest value $210{\;}kg/cm^2$, and the solidification conditions were 0.55 of the water/cement ratio and curing for 14 days. Also, the results of leaching test by EPT(Environmental Protection Agency-Toxicity Test) were showed that the solidified lead has leached out under 10%, which was less than 0.173 mg/L of EPA standard. As leaching solutions, the demineralized water, 0.1N acetic acid solution, and synthetic brine were used. and the observations by SEM of the solidified lead-laden solid after EPT leaching test were indicated the severe erosion on solid surface.

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A New Approach of Strength Prediction of High Strength Concrete by the Equivalent Age (적산온도기법에 의한 고강도콘크리트의 강도예측)

  • Kwon, Young-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.177-183
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    • 2004
  • The maturity concept is based on the fact that concrete gains strength with time as a result of the cement hydration and, thus the strength of concrete is related to the degree of hydration of the cement in concrete. The rate of hydration, as in any chemical reaction, depends primarily on the concrete temperature during hydration. Therefore, the aim of the study is to investigate of the correlation between strength of high-strength concrete and maturity that is expressed as a function of an integral of the curing period and temperature.

Modeling of Setting Behavior in Fresh Concrete considering Microstructure Formation

  • Cho, Ho-Jin;Song, Ha-Won;Byun, Keun-Joo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.490-493
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    • 2004
  • In the analysis of early-age concrete behavior, the fresh concrete is considered as a structural element immediately after mixing. But for the activation of real structural behavior in the fresh concrete, the so-called setting time is necessary a few hours after the beginning of hydration reaction. In this paper, analysis on the setting behavior is carried out by proposing an analytical model based on the percolation theory as well as the expanding cluster model by defining the setting as a microstructure formation in fresh concrete. An experimental investigation is also carried out to show the influences of curing temperature, mineral admixtures and chemical admixture on setting behavior of fresh concrete. Finally, the analytical results using proposed model are compared with the experimental results for the sake of verification.

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Effects of Reactive Diluents on the Electrical Insulation Breakdown Strength and Mechanical Properties in an Epoxy System

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.14 no.4
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    • pp.199-202
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    • 2013
  • In order to study the effect of reactive diluents on the electrical insulation breakdown strength and mechanical properties of, a polyglycol and an aliphatic epoxy were individually introduced to an epoxy system. Reactive diluents were used in order to decrease the viscosity of the epoxy system; polyglycol acted as a flexibilizer and 1,4-butanediol diglycidyl ether (BDGE) acted as an aliphatic epoxy, which then acted as a chain extender after curing reaction. The ac electrical breakdown strength was estimated in sphere-to-sphere electrodes and the electrical breakdown strength was estimated by Weibull statistical analysis. The scale parameters of the electrical breakdown strengths for the epoxy resin, epoxy-polyglycol, and epoxy-BDGE were 45.0, 46.2, and 45.1 kV/mm, respectively. The flexural and tensile strengths for epoxy-BDGE were lower than those of the epoxy resin and those for epoxy-polyglycol were lower than those of the epoxy resin.

Effect of Electric Frequency on the Partial Discharge Resistance of Epoxy Systems with Two Diluents

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.14 no.6
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    • pp.317-320
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    • 2013
  • Partial discharge resistance for the epoxy systems with two diluents was investigated in the rod-plane electrodes arrangement, and the effect of electric frequency on the partial discharge resistance was also studied. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and 1,4-butanediol diglycidyl ether (BDGE) or polyglycol (PG) as a reactive diluent was introduced to the DGEBA system, in order to decrease the viscosity of the DGEBA epoxy system. BDGE was acted as a chain extender, and PG acted as a flexibilizer, after the curing reaction. To measure the partial discharge resistance, 5 kV alternating current (ac) with three different frequencies (60, 500 and 1,000 Hz) was applied to the specimen in a rod-plane electrode arrangement, at $30^{\circ}C$. PG had a good effect, while BDGE had a bad effect on the partial discharge resistance of the DGEBA system, regardless of the electric frequency.

SOLUTION OF THE SUPER BESSEL WAVE EQUATION WITH INTEGRAL PARAMETER m

  • Lee, Nae-Ja;Liu, Chang-Keng
    • Bulletin of the Korean Mathematical Society
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    • v.20 no.2
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    • pp.99-103
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    • 1983
  • Internal heat generation is one of the insidious conditions affecting the quality of an industrial product after it is cast, coated, molded, forged or laminated. Frequently, the product is pressed into service before the exothermic chemical reactions in the generic material has been completed. The heat liberated from this continuing chemical reaction or the residual deformation from the rheological activities in the materials must be adequately removed or prevented, or the product may be discolored, warped, weakened or even "ignited" spontaneously. Numerous instances of premature structural failures, product-recalls, and/or system-malfunctions have been recorded in recent history. The Coulee Dam was poured with pre-chilled concrete just to negate this freakish encore. It is well-known that concrete (a non-isotropic conducting medium), for instance, takes 28 days to develop its full strength. During this period of curing it is conceivable that the processes of internal heat generation, heat conduction and heat dissipation take place simultaneously inside the medium.he medium.

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Evaluation of Thermal Property and Fluidity with Underfill for BGA Package (BGA 패키지를 위한 언더필의 열적 특성과 유동성에 관한 연구)

  • Noh, Bo-In;Lee, Bo-Young;Kim, Soo-Jung;Jung, Seung-Boo
    • Journal of Welding and Joining
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    • v.24 no.2
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    • pp.57-63
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    • 2006
  • In this study, the curing kinetics and thermal degradation of underfill were investigated using differential scanning calorimetry (DSC) and thermo gravimetry analysis (TGA). The mechanical and thermal properties of underfill were characterized using dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). Also, we presented on underfill dispensing process using Prostar tool. The non-isothermal DSC scans at various heating rates, the exothermic reaction peak became narrower with increasing the heating rate. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The results of fluidity phenomena were simulated using Star CD program, the fluidity of the underfills with lower viscosity was faster.