• 방사선산업학회지
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• 제4권1호
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• pp.19-23
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• 2010

Vinyl ester (VE) resins, introduced in the late 1960s, have made large strides in reinforced plastics applications as adhesive and matrix materials on their appropriate mechanical performance characteristics in the glassy state. Generally, VE resins are a group of dimethacrylate resins based on bisphenol A type epoxy resin. They exhibit easy handling properties as well as good resistance to most chemical agents due to their mechanical and thermal properties. In this study, the effects of curing methods of vinyl ester resins on gel contents, flexural strength and dynamic mechanical properties were investigated. Thermal curing (room temperature, $80^{\circ}C$) and electron beam curing were used to crosslink a VE resin/styrene complex (65/35 wt%) with methyl ethyl ketone peroxide (MEKPO) as a catalyst and an 8 wt% cobalt naphthenate in styrene solution as a accelerator. For the samples, gel contents as well as flexural strength and dynamic mechanical properties were characterized and compared by soxhlet apparatus, universal testing machine (UTM) and dynamic mechanical analysis (DMA). As a result, the electron-cured VE resin was confirmed as a better condition than those for gel contents, flexural strength and dynamic mechanical properties, respectively.

• 방사선산업학회지
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• 제4권3호
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• pp.271-276
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• 2010

Epoxy resin has wide application in various industrial fields because of their good mechanical strength, superiority adhesion and low shrinkage etc. And the typical curing method for epoxy resins is thermal and press compaction. However, a curing method was used electron beam process in this study. Epoxy acrylate was fabricated from mixture of epoxy, acrylic acid, tetraphenylporphyrin (TPP) and hydroquinone monomethyl ether (MEHQ) with mole ratios. Then electron beam irradiation effect on the curing of the epoxy acrylate resin was investigated various absorption dose in nitrogen atmospheres at room temperature. The dynamic mechanical and thermal properties of the irradiated epoxy acrylate resins were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analyzer (TGA). And the tensile and flexural strength were measured by an universal tensile machine (UTM).

• Macromolecular Research
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• 제10권6호
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• pp.332-338
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• 2002

The effect of an electron beam and ${\gamma}$-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) as epoxy resin were used. The epoxy resins containing 1.0-3.() wt% of triarylsulphonium hexafluoroantimonate(TASHFA) and triarylsulphonium hexafluorophosphate(TASHFP) as initiator were irradiated under nitrogen at room temperature with different dosage of EB and ${\gamma}$-rays from a Co$^{60}$ u source. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of EB and ${\gamma}$-ray irradiation. The thermal properties of cured epoxy were investigated using dynamic mechanical thermal analysis. The chemical structures of cured epoxy were characterized using near infrared spectroscopy. Mechanical properties such as flexural strength, modulus were measured. The gel fraction of DGEBA with ${\gamma}$-ray was higher than that of the epoxy with EB at the same dose. Young's modulus of the sample irradiated by ${\gamma}$-ray is higher than that of sample cured by EB. From the result of strain at yield, it was found that the epoxy cured by ${\gamma}$-ray had a higher stiff property compared with the irradiated by EB.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.75-79
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• 2008

In this paper, we measured the activation energy of the Bisphenol A type Epoxy resin (DGEBA)-Jeffamine system according to an irradiation. We put the mixed solutions to the silicon mold after mixing both DGEBA(216g) and Jeffamine(93.9g), curing agent of amine system. The mixed solutions were cured in the atmosphere during 24hours after finishing the first curing during 4hours in the vacuum oven under $80^{\circ}C$. The mixed solutions were cured in the atmosphere during 24hours after finishing the second curing during 12hours in the vacuum oven under $60^{\circ}C$ again. Prepared samples were irradiated to the dose rate of 8kGy/hr with 500kGy, 700kGy, 1000kGy, 1500kGy, 2000kGy, 2500kGy. Experimental results indicated activation energy of the samples reduced as the irradiation dose increased because of the peroxides of the Epoxy created by the oxidation and the radiation.

• 한국연초학회지
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• 제22권2호
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• pp.138-142
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• 2000

The effects of stalk cutting time and environmental factors such as air temperature, leaf temperature, solar radiation and leaf moisture content during harvesting and curing in burley tobacco(Nicotiana tabacum L.) on weight loss of fresh stalks and sunburning in leaves were investigated at Chonju Experiment Station, Korea Ginseng & Tobacco Research Institute in 1996 and 1997. Twelve to fifteen percent of the fresh weight was lost in 3 to 4 hours after stalk-cutting, and sunburned leaves could be observed in case of stalk cutting between 11:00 and 15:00 O'clock on a clear sunny day, when the air temperature was 34 to 35$^{\circ}C$, leaf temperature 52 to 54$^{\circ}C$, and solar radiation 700 to 940 w/$m^2$. The leaves exposed to this weather condition were sunburned within 1 hour after stalk cutting. But low temperature (below $25^{\circ}C$) with high solar radiation(above 700w/m2) or high temperature(above 3$0^{\circ}C$) with low solar radiation (below 600w$m^2$) did not induce the sunburn damage in leaves. As the leaf temperature and leaf moisture content were higher, the sunburned leaves increased. The leaves at the higher stalk position were more easily sunburned than those at the lower. This result indicates that the immature leaves with higher chlorophyll content might be more susceptible to sunburning.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.103-106
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• 2003

In this work the novel potential epoxy resins, were synthesized and acrylated. Their structures were confirmed by means of FTIR, $^1H NMR, and^{13}/C NMR$ spectroscopies. Also, we were to note the effect of W curing on functional group changes of VE/UP blend system after UV curing.

• 대한화학회지
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• 제21권4호
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• pp.284-292
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• 1977

메타크릴酸과 diglycidyl ether 型 低分子量의 에폭시樹脂로부터 에폭시樹脂의 dimethacrylate를 合成하였으며 이 prepolymer와 단위체인 스티렌 및 polyethyleneglycol dimethacrylate 混合物의 電子線硬化에 關하여 檢討하였다. 에스테르化反應은 메타크릴酸에 對하여 約 250∼300ppm以上의 hydroquinone과 $1{\%}$(wt) 以下의 triethanolamine의 添加로서 거의 定量的으로 進行되었다. 空氣中에서 행한 硬化에 있어서는 단위체 濃度10 ∼ $30{\%}$에서 最高의 겔分率을 나타내었으며 겔化速度는 prepolymer의 未反應 에폭시基와 酸의 存在에 의하여 減少되었고 polyethyleneglycol dimethacrylate內의 polyethyleneglycol의 重合度가 增加함에 따라 增加하였다. 窒氣中과 空氣中에서 겔化速度는 별다른 差異가 없었으나 生成物 性質의 差異로 보아 硬化時의 酸素의 影響은 상당히 컸으며 polyethyleneglycol dimethacrylate類를 단위체로 使用時는 더욱 그러하였다.

• 한국전산구조공학회논문집
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• 제25권3호
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• pp.203-209
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• 2012

본 논문에서는 상온 및 방사선 경화 복합재 풍력 블레이드의 구조성능을 비교하기 위하여 단면 강성, 정적응력 및 동적 고유 진동수를 해석하였다. 먼저 상온 및 방사선 경화공정에 의한 복합재료 시편의 탄성계수 등 물성 값을 적용하였다. 블레이드의 단면 강성 값은 고형 복합재료 보 이론을 적용하여 유한요소 적분법으로 계산하였다. 허브 체결부위를 포함한 소형 풍력 블레이드를 상용 유한요소 프로그램으로 모델링하여 최대 변위와 응력분포 등을 확인하였다. 또한, 풍력 블레이드의 회전속도에 따른 원심력 효과를 고려하여 고유 진동수 해석을 병행하였다. 이와 같은 일련의 해석결과를 상호 비교함으로써, 상온 및 방사선 경화 복합재료의 물성 값 차이에서 기인하는 풍력 블레이드의 구조성능 변화를 정량적으로 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1115-1116
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• 2011

• 한국연초학회지
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• 제5권1호
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• pp.79-85
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• 1983

The greenhouse bulk curing and drying system utilization of the direct solar energy was tested to evaluate that how much fuel could be saved for curing flue-cured tobacco at the Dae Gu Experiment Station (North latitude : $35^{\circ}$49'), in 1979-1982. The air temperature and total radiation were 19.0 to 38.5$^{\circ}C$ and 1311.0 to 1412.7 cal/$\textrm{cm}^2$/day during the 4 replicated curing test, respectively. The greenhouse bulk curing and drying system was able to cut fuel consumption by 32% compared with the conventional bulk curing barn. We could obtain almost same utilization efficiency of solar energy in 1982 compare with normal year, mainly increasing the heat receiving area.