• Title, Summary, Keyword: silicone

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Preparation and Physical Properties of Silicone Hydrogel Ophthalmic Lens Containing Hydrophilic Monomer

  • Lee, Min-Jae;Sung, A-Young
    • Journal of the Korean Chemical Society
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    • v.60 no.4
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    • pp.261-266
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    • 2016
  • The major physical characteristics of macromolecules used in silicone hydrogel ophthalmic lenses include optical transmittance, oxygen permeability, water content, and refractive index. For the preparation of highly functional silicone hydrogel lens materials, two silicone monomers were used in the presence of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA). The samples containing HEMA and HPMA had oxygen transmissibility (Dk) values in the range of 73.38–50.98 × 10-11 (cm2/s) (mLO2/mL×mmHg) and 71.94–42.80 × 10-11 (cm2/s) (mLO2/mL×mmHg), respectively. Furthermore, the water contents of samples containing HEMA and HPMA were in the range of 32.73–34.67% and 31.94–33.74%, respectively, and the refractive indices were in the range of 1.4348–1.4364 and 1.4385–1.4407, respectively. Thus, silicone monomers containing HEMA and HPMA are expected to be useful for fabricating high-oxygen-permeability silicon hydrogel ophthalmic lenses.

Electrical and Mechanical Properties of Silicone Rubber for High Voltage Insulation (고압절연용 실리콘고무의 전기특성 및 물성에 관한 연구)

  • Lee, J.H.;Ji, W.Y.
    • Elastomers and Composites
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    • v.37 no.2
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    • pp.115-123
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    • 2002
  • This study was carried out to investigate the influences or the vinyl content of polydimethylsiloxane(PDMS) and type of silica on the electrical and mechanical properties of silicone rubber far high voltage insulation. When the content of vinyl group was increased, cross-linking density and hardness were increased, and tensile strength, volume resistivity and tracking resistance were improved. The mechanical and electrical properties of silicone rubber reinforced with fumed silica were higher than those of silicone rubber reinforced with precipitated silica. It was found that the electrical and mechanical properties of silicone rubber were influenced greatly by the water contents of silica.

Effect of Methyl Silicone, TBHQ and BHA/BHT on Frying and Storage Stabilities of the Vegetable Salad Oil in High Density Polyethylene Bottles (TBHQ, BHA/BHT 및 Methyl silicone이 식용유의 저장성과 고온에서의 안정성에 미치는 영향)

  • Rhee, Joon-Shick
    • Korean Journal of Food Science and Technology
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    • v.10 no.2
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    • pp.250-257
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    • 1978
  • Functional additives such as methyl silicone, TBHQ and BHA/BHT have been evaluated for their effects on storage and frying stabilities of the vegetable salad oil. All test results strongly suggest that methyl silicone improved the frying stability and TBHQ improved the storage stability. BHA/BHT improved neither storage stability, nor frying stability of the vegetable saladoil. Based on the test results, it is recommended that methyl silicone in the range of $1.0{\pm}0.5ppm$ and TBHQ in the range of 200ppm be added to the vegetable salad oil for the improvement of frying and storage stabilities.

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The surface discharge performance of silicone rubber in the Salt fog test (Salt fog 시험에서 silicone rubber에서 발생하는 방전 전류의 특성)

  • 강성화;박영국;이광우;김완수;이용회
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.565-569
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    • 1999
  • In these days, the silicone insulators have been increasingly studied and applied for outdoor insulators because it has superior characteristics than porcelain and glass insulators, which have been used for outdoor insulators. First of all, The excellent performance of the silicone rubber in polluted and wet conditions is attributed to the ability of the material to maintain the hydrophobicity of the surface in the presence of severe contamination and wet conditions. This is because of the presence of low molecular weight mobile fluid in the silicone rubber which diffuses to the surface and to above the contamination layer. But, the leakage current and some surface discharge occurs on surface of the composite polymeric insulation materials when the insulator is used for a long time with severe contaminative condition and it can lead the contamination flashover. So the leakage current and the discharge current are important to estimate the condition of the silicone rubber surface. In this paper, the average leakage current, the relation of surface discharge current and phase angle were study to investigate electrical conduction of silicone rubber surface with the salt fog condition.

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Preparation of Silicone Rubber Membrane and its Porosity (Silicone Rubber Membrane의 제조 및 기공특성)

  • Lee, Seung-Bum;Kim, Hyung-Jin;Hong, In-Kwon
    • Elastomers and Composites
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    • v.30 no.3
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    • pp.185-194
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    • 1995
  • Membrane process has been employed to separate a specific substance from gas or liquid mixture, and treat wastewater. This is due to the fact that the substance of mixture can be permeated and separated selectively by membrane. Since Initial equipment and operation costs are not expensive, membrane process has been adopted in various fields such as petroleum Industry, chemistry, polymer, electronics, foods, biochemical industry and wastewater treatment. In this study, $CaCO_3$ particles impregnated in silicone rubber network were extracted by using supercritical carbon dioxide and pore distribution of silicone $rubber-CaCO_3$ was investigated with varying amount of extract. Silicone rubber has excellent mechanical properties such as heat-resistance, cold-resistance etc. and $CaCO_3$ has microporous structure. It is possible to make silicone $rubber-CaCO_3$ composite sheets via work-intensive kneading processes. In so doing $CaCO_3$ particles become distributed and impregnated in silicone rubber network. Supercritical carbon dioxide diffuse through composite sample, then sample is swollen. $CaCO_3$ in silicone rubber network Is dissolved in supercritical carbon dioxide, and its sites become pores. Pore distribution, pore shape and surface area are observed by SEM(scanning electron microscope) micrograph and BET surface area analyzer examination respectively. Pore characteristics of membrane suggest the possibilities that the membrane can be used for process of mixture separation and wastewater treatment.

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Acute Pulmonary Embolism by Silicone Injection: Radiologic Findings (실리콘액 주사에 의한 급성 폐색전증: 영상의학적 소견)

  • Lee, Jae-Kyo
    • Yeungnam University Journal of Medicine
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    • v.21 no.2
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    • pp.215-223
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    • 2004
  • Silicone is widely used for medical purposes in breast augmentation and other cosmetic procedures. Illegal injections of silicone in human beings might have adverse effects and one of the serious problems is a silicone embolism. We experienced five cases of unusual respiratory difficulties after an injection of liquid silicone in the breast, vagina, uterus, and hip. They were all young adult females, who were previously healthy. One of them died after the injection. The three remaining patients were admitted because of dyspnea, coughing, chest discomfort and bilateral pulmonary infiltration after the silicone injection. A transbronchial lung biopsy and autopsy disclosed many oil like materials filling the alveolar septal capillaries. Three patients underwent a computed tomogram (CT), which revealed multifocal airspace consolidations at the peripheral and nondependent portions of both lungs, which is a different finding from other thromboembolisms. Lung scans of the disclosed abnormalities were compatible with silicone induced pulmonary embolism.

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Analysis of Physical Performance, Hygiene and Safety of Silicone-Laminated Stretch Material (실리콘이 라미네이팅된 신축성 소재의 위생 및 안전성과 역학적 성능)

  • Kwon, Myoung-Sook;Jung, Gi-Soo
    • Journal of the Korean Society of Clothing and Textiles
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    • v.31 no.1
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    • pp.77-84
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    • 2007
  • The purpose of this study was to investigate and to compare the performances of silicone laminated materials sold for swimming cap in market, to get the basic data for product development. We selected 4 specimens and tested their air permeability, waterproofness and breathability. We also tested the physical and mechanical properties of the specimens using KES system. Silicone-laminated material was not bursted on high hydraulic pressure since silicone membrane gave waterproofness while PU/Polyester substrate gave elasticity. It didn't have air permeability and breathability at all. Any toxic materials such as Formaldehyde, Deldrin, PCP, Amin, TDBPP were not detected in silicone-laminated material and other materials. Silicone-laminated material had higher stretchability with the low force but it had lower elastic recovery and shape stability comparing to PU laminated material. It had lower flexibility than PU laminated material. It had lower unrecoverable amount in shearing direction. Friction coefficient was higher in silicone-laminated material than PU laminated material due to its surface stickiness. It was compressed easily and its compression resiliency was higher with compared to PU laminated material.

Adhesion Characteristics of Semiconductive and Insulating Silicone Rubber by Oxygen Plasma Treatment (산소 플라즈마 처리에 의한 반도전-절연 실리콘 고무의 접착 특성)

  • Lee Ki- Taek;Huh Chang-Su
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.2
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    • pp.153-157
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    • 2006
  • In this work, the effects of plasma treatment on surface properties of semiconductive silicone rubber were investigated in terms of X-ray photoelectron spectroscopy (XPS) and contact angles, The adhesion characteristics of semiconductive-insulating interface layer of silicone rubber were studied by measuring the T-peel strengths, The results of the chemical analysis showed that C-H bonds were broken due to plasma discharge and Silica-like bonds(SiOx, x=3${\~}$4) increased, It is thought that semiconductive silicone rubber surfaces treated with plasma discharge led to an increase in oxygen-containing functional groups, resulting in improving the degree of adhesion of the semiconductive-insulating interface layer of silicone rubber. However, the oxygen plama for 20 minute produces a damaged oxidized semiconductive silicone rubber layer, which acts as a weak layer producing a decrease in T-peel strength, These results are probably due to the modifications of surface functional groups or polar component of surface free energy of the semiconductive silicone rubber.

Insulation rehabilitation of water tree aged cables by silicone treatment (실리콘 처리에 의한 수트리 열화케이블의 절연회복)

  • 김주용;송일근;한재홍;이동영;문재덕
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.14 no.1
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    • pp.14-21
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    • 2000
  • This paper presents the results of performance evaluation of silicone treatment technique which was developed for the insulation rehabilitation of water tree aged XLPE power cables. We treated the water tree aged 325 [$\textrm{mm}^2$] CN/CV cables with silicone, and then analyzed the degree of insulation rehabilitation as a function of time. AC breakdown test was conducted to evaluate insulation rehabilitation. The diagnosis test using relaxation current measurement and the characteristic analysis of insulation were also performed to estimate silicone treated cable. AC breakdown strength of silicone treated cable for one year was increased, resulting from the chemical reaction between silicone fluid and water. This experiment showed that the silicone treatment technique was effective for insulation rehabilitation of the water tree aged cables.

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Finite Element Analysis of Residual Stress Evolution during Cure Process of Silicone Resin for High-power LED Encapsulant (고출력 LED 인캡슐런트용 실리콘 레진의 경화공정중 잔류응력 발달에 대한 유한요소해석)

  • Song, Min-Jae;Kim, Heung-Kyu;Kang, Jeong-Jin;Kim, Kwon-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.2
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    • pp.219-225
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    • 2011
  • Silicone resin is recently used as encapsulant for high-power LED module due to its excellent thermal and optical properties. In the present investigation, finite element analysis of cure process was attempted to examine residual stress evolution behavior during silicone resin cure process which is composed of chemical curing and post-cooling. To model chemical curing of silicone, a cure kinetics equation was evaluated based on the measurement by differential scanning calorimeter. The evolutions of elastic modulus and chemical shrinkage during cure process were assumed as a function of the degree of cure to examine their effect on residual stress evolution. Finite element predictions showed how residual stress in cured silicone resin can be affected by elastic modulus and chemical shrinkage behavior. Finite element analysis is supposed to be utilized to select appropriate silicone resin or to design optimum cure process which brings about a minimum residual stress in encapsulant silicone resin.