• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.203-206
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• 2017

The effect of the content of microsilica and nanosilica continuously modified with hydroxy silane and epoxy-modified silicone in cycloaliphatic epoxy/microsilica/nanosilica composites (EMNCs) on the mechanical and water repellent properties was evaluated. Surface-modified micro- and nanosilica was well-mixed with a cycloaliphatic epoxy resin in the presence of polyester-modified polydimethylsiloxane (PEM-PDMS) as a dispersing agent using an ultrasonicator. Tensile and flexural tests were carried out using a universal testing machine (UTM). The water repellent property was evaluated by contact angle measurements of water on the composite surface. Tensile strength of the composite could be enhanced by 32.2% up to 91.4 MPa, and the flexural strength was raised to 122.0 MPa, which is 38.8% higher than that of neat epoxy. The contact angle of water on the composite was as high as $104.1^{\circ}$.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.155-158
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• 2016

The effect of microsilica content modified with silicone-modified epoxy on electrical and mechanical properties of cycloaliphatic epoxy/microsilica system was investigated. The cycloaliphatic epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and curing agent was an anhydride. Surface of microsilica was modified with silicone-modified epoxy. Electrical breakdown strength, the most important property for electrical insulation materials was tested. Tensile and flexural tests were also performed using universal testing machine (UTM). The microcomposite with 60 wt% microsilica shows maximum values in electrical breakdown strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.90-90
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• 2010

Cycloaliphatic Epoxy와 Bisphenol Epoxy를 각각 mol-wt%비 (80:20, 50:50, 20:80)로 혼합하고 Epoxy Silaned Silica, 바ed Silica, Spherical Silica, ATH(Aluminum Trihydrate)를 충진하여 내트래킹 특성 및 인장강도, 충격강도 등의 기계적 강도를 비교하였다. Cycloaliphatic 수지는 Huntsman사(社)의 CY5622, Bisphenol 수지는 Hexion사(社)E의 Epikote2200을 사용하였으며, Silaned Silica 및 Fused Silica는 Quatzwerke사(社)의 W12, FW12를 사용하였다. 전체 혼합물 중, 에폭시는 약 36%, 실리카는 약 34~540%, ATH는 약 10~30% 이다. 실험결과, ATH 함량이 높은 조성 및 Epoxy Silaned Silica를 사용한 조성과 Cycloaliphatic 혼합비율이 높은 조성이 우수한 내트래킹 특성을 보였다. 또한, Silica의 함량이 증가할수록 기계적 강도가 증가하였으며, Silaned Silica를 사용하였을 때 가장 우수한 특성을 나타내었다. 본 실험의 결과를 통해 옥외용 내트래킹 특성 규격인 IEC60587 4.5kV/6h를 만족하는 조성에 대해 가늠이 가능하였고, 각 조성에 따른 기계적 강도의 확인이 가능하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.431-434
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• 2002

This paper reports on the evaluation of weathering resistance, tracking test and salt-fog of various kinds of cycloaliphatic epoxy systems. It was found that UV irradiation induced the loss of hydrophobic level due to the chain scission attack at the surface. It could be seen that samples containing an UV absorbent/antioxidant and a silicone oil additive knave a good performance in weathering ageing, whereas ATH filled ones have high resistance against tracking failure than others. Under salt-fog test, specimens mixed with silicone oil could suppress leakage current development. It was thought that silicone oil mixed into cycloaliphatic epoxy system could lead to lower the surface energy and to retain hydrophobic properties for a long time, which are desirable for outdoor performances.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.74-77
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• 2015

The cure kinetics of a neat epoxy system and epoxy/silica composite were investigated by DSC analysis. A cycloaliphatic type epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and curing agent was anhydride type. To estimate kinetic parameters, the Kissinger equation was used. The activation energy of the neat epoxy system was 88.9 kJ/mol and pre-exponential factor was 2.64×10¹² min⁻¹, while the activation energy and pre-exponential factor for epoxy/silica composite were 97.4 kJ/mol and 9.21×10¹² min⁻¹, respectively. These values showed that the silica particles have effects on the cure kinetics of the neat epoxy matrix.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1840-1847
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• 2016

The surface of nanosilica and microsilica was modified in order to develop a high voltage insulation material for outdoor application. The modified silicas were well dispersed in an aliphatic cyclic epoxy resin. Dielectric properties were studied for 8 kinds of specimens: 1 kind of neat epoxy, 3 kinds of epoxy/microsilica composites, and 4 kinds of epoxy/microsilica/nanosilica composites. Complex dielectric constants were measured in the range of 10-2~1.2 Hz at room temperature.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.82-85
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• 2015

Mechanical and electrical properties of epoxy/silica microcomposites were investigated. The cycloaliphatic- type epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and the curing agent was of an anhydride type. To measure the glass transition temperature (Tg), dynamic differential scanning calorimetry (DSC) analysis was carried out, and tensile and flexural tests were performed using a universal testing machine (UTM). Electrical breakdown strength, the most important property for electrical insulation materials, and insulation breakdown strength were also tested. The microcomposite with 60 wt% microsilica showed maximum values in mechanical and electrical properties.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1323-1326
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• 1994

the application of epoxy composite materials for outdoor insulating systems has some significant advantages compared with conventional inorganic materials, that is low weight in combination with high mechanical strength, small dimensions and design versatility. The experimental results for the basis composition and interlace characteristics of the matrix resin/inorganic fillers($SiO_2$) which are the composite materials have been studied. The electrical characteristics(electrical breakdown, dielectric, insulating resistivity, tracking) and mechanical characteristics( tensile strength, elongation, flexible strength) in the epoxy composite materials have been studied. The life of the epoxy composite material was evaluated by accelerated Weather-Ometer test and the degradation process due to outdoor exposure condition is discussed with respect to the mechanical and electrical properties.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.30-37
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• 2002

This paper reports on the results of weathering test, tracking test and salt-fog test of various kinds of cycloaliphatic epoxy systems. UV irradiation dramatically induced the loss of surface hydrophobicity due to the chain scission attack at the surface under UV irradiation. It could be seen that samples containing an UV absorbent/antioxidant and a silicone oil additive have a good performance in weathering test, while ATH(alumina tri-hydrate) filled ones have high resistance against tracking failure than others. Under salt fog chamber test, specimens mixed with silicone oil are able to suppress leakage current development. It was thought that silicone oil mixed into cycloaliphatic epoxy system could lead to lower the surface energy and to retain hydrophobic properties for a long time, which are desirable for outdoor use.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.200-204
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• 2008

The curing kinetics of diglycidyl ether of bisphenol F (DGEBF) with an asymmetric cycloaliphatic amine curing agent were examined by thermal analysis in both isothermal and dynamic curing conditions. From the residual curing of the samples partially cured in isothermal condition and from the dynamic curing with various heating rates, it was found that there exist two kinds of reactions such as at low temperature and at high temperature regions. It was thus also found that the cure parameters obtained from the isothermal curing kinetic model hardly estimate experimental results for a degree of cure larger than 0.6. The activation energies and frequency factors of these two kinds of reactions were obtained from the dynamic curing experiments with various heating rates. From the curing analysis, it was verified that the total cure kinetics for low degrees of cure is dominated by the cure reaction in the low temperature region.