• Title/Summary/Keyword: repellency

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The Effects of Environmental Factors on Degradation and Hydrophobicity Recovery Characteristics in RTV Silicone Rubber (RTV 실리콘 고무의 열화 및 발수성 회복 특성에 미치는 환경인자의 영향)

  • Heo, Chang-Su;Yeon, Bok-Hui;Jo, Hyeon-Uk;Hwang, Myeong-Geun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.6
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    • pp.462-468
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    • 1999
  • Room temperature vulcanizing (RTV) silicone rubber has been widely used to coat porcelain insulators to render water repellency to prevent formation of water film on the surface and thus to suppress the leakage current and consequently flashover. However, the electrical property and the hydrophobicity of RTV silicone rubber coating under outdoor condition may be influenced by many environmental factors. In this studyvarious treatments, such as salt-fog, salt water immerging and UV irradiation were applied to the samples to investigate the change of the electrical property and hydrophobicity. As a result the leakage current increased and contact angle decreased asthe degradation time is longer. But the degraded RTV silicone rubber has recovered its hydrophobicity during the drying time in ambient condition because LMW(Low Molecular Weight) silicone fluid diffused from the bulk to the surface.

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Surface Property of PET Fabric Treated with $CF_4$ Plasma and $C_2F_6$ Plasma (플루오르 화합물을 플라즈마 처리한 PET 직물의 표면특성)

  • 김태년;모상영
    • Textile Coloration and Finishing
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    • v.11 no.1
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    • pp.25-33
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    • 1999
  • PET fabric was grafted with $CF_4$ or $C_2F_6$ plasmas generated by glow discharge. The water repellency of plasma-treated fabrics were evaluated with contact angle meter. The change in surface morphologies was observed by SEM, and the change of surface chemical characteristics were analyzed by FT-IR, ESCA and microchemical analysis technique. The results obtained are as follows : 1) The contact angle of plasma-treated fabric was over $150^\circ{C}$. 2) It was observed by SEM that the surface of treated substrate was over coated with thin film formed by the fluorocarbon plasma treatment. 3) According to ESCA analysis, there were prevailing -CHF-, $-CF_2$- and a little $-CF_3$ components on fluorocarbon plasma treated substrate. -CHF- and $-CF_2$- components were reduced by washing, and $-CF_2$- component was recovered by heat treatment. 4) In consideration of quantitative analysis of fluorine and F/C ratio by ESCA, we found that fluorination reached to the inner of substrate.

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Repellent activity of aromatic medicinal plant extracts against Aedes aegypti(Diptera: Culicidae) (방향성 한방식물체 조추출물의 에짚트숲모기(Aedes aegypti)에 대한 기피활성에 관한 연구)

  • 최한영;양영철
    • Journal of environmental and Sanitary engineering
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    • v.17 no.3
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    • pp.110-114
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    • 2002
  • The repellent activity of methanol extracts from 8 aromatic medicinal plant species and a steam distillate against blood-starved Aedes aegypti (L.) females was laboratory examined by skin test and compared with that of N,N-diethyl-m-toluamide (deet). Reponeses varied according to Plant species. At a dose of $0.1mg/\textrm{cm}^2$, potent repellency against adult mosquitoes was obtained with extracts of Cinnamomum camphora (94.1 %) Cinnamomum cassia bark (91.2%), Eugenia caryophyllata flower bud (72.2%), and Tilia amurensis (69.4%). Repellent activity of these plant extracts was comparable to that of deet (83.4%). The plants described merit further study as potential mosquito-repellent agents.

Durable Water and Oil Repellent Finish of Wool Fabric(I) (양모직물의 내구성 발수 및 발유가공(I))

  • 나도춘;정순량;박병기;정경락
    • Textile Coloration and Finishing
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    • v.10 no.1
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    • pp.33-37
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    • 1998
  • It is rather important in the water and oil repellent finishing for wool fabric what kind of water-repellent agents will be used. In many cases, Fluorocarbon-based water-repellent agents(eg.Oleophobol-S), the surface tensions of which very low, were recom-mended on account of good water and oil repellencies. In repellent finishing, fabrics were padded in a bath which contained aqueous solution of water-repellent agents, and wetting agents, followed by drying and curing. The most suitable treating condition for excellent repellency was as follows Fabrics were padded at liquor pick-up ratio of 50%, with aqueous solution which contained $30g/\ell$ of water-repellent agents, and $40g/\ell$ of wetting agents. And the padded fabrics were dried at $110^\circ{C}$ for 1 minute, and cured at $160^\circ{C}$ for 2 minutes. For the fabrics, water and oil repellencies and durability to repeated dry-cleanings are observed.

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Evaluation of Repellency Effect of Two Natural Aroma Mosquito Repellent Compounds, Citronella and Citronellal (천연 아로마 모기 기피제 (시트로넬라와 시트로넬롤)의 기피력 효과 측정)

  • Jung Eun-Suk;Yun Hwa-Kyung
    • Proceedings of the KAIS Fall Conference
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    • 2005.05a
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    • pp.287-289
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    • 2005
  • Repellent effcacies of two natural aroma compounds. citronella and citronellal, against mosquitoes were evaluated both in field and in vitro. In vitro, the experiment was conducted with three controlled bands impregnated with $30\%$ citronella extract, $15\%$ citronella extract and $30\%$ citronellal extract, and with band impregnated $30\%$ citronella in field. Raw data was obtained by the means of counting numbers bitten by mosquitoes per unit time, namely human bait method. Comparative repellent efficacies of above three controlled bands were calculated at $86\%$, $73\%$, and $78\%$, respectively in vitro, and $80\%$ in field, showing high repellent effectiveness against mosquitoes. This estimation was also confirmed by t-test compared between control group and each experimental group.

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Bioinspired Nanoengineering of Multifunctional Superhydrophobic Surfaces

  • Choi, Chang-Hwan
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.102-133
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    • 2015
  • Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. Especially, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing. Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing.

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Superhydrophobic and Hydrophobic Anodic Aluminum Anodic Oxide Layer: A Review (초발수성 및 발수성 알루미늄 양극산화피막의 최신 연구 동향)

  • Lee, Junghoon
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.11-20
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    • 2018
  • Hydrophobic and Superhydrophobic surfaces are promising technology for the surface finishing of metallic materials due to its water-repellency. Realization of highly water-repellent surface on aluminum and its alloys provides various functionalities for real application fields. In order to realize the hydrophobic/superhydrophobic surfaces on aluminum and its alloys, various technologies have been demonstrated. Especially, traditional anodic oxidation for aluminum has been widely employed for the morphological texturing of surfaces, which is essential to enhance the hydrophobic efficiency. De-wetting superhydrophobic surface on aluminum provides various exceptional properties, such as anti-corrosion, anti-/de-icing, anti-biofouling, drag reduction, self-cleaning and liquid separation. Nevertheless, the durability and stability of superhydrophobic surfaces still remain challenges for their actual applications in engineering systems and industry. In this review, the theoretical/experimental studies and current technical limitations on the hydrophobic and superhydrophobic surface using anodic oxidation of aluminum have been summarized.

Surface-Properties of Poly(Ethylene Terephthalate) Fabric by In-line Atmospheric Plasma Treatments (연속 대기압 플라즈마를 처리한 폴리에스테르 섬유의 표면 특성)

  • Kwon, Il-Jun;Park, Sung-Min;Koo, Kang;Song, Byung-Kab;Kim, Jong-Won
    • Textile Coloration and Finishing
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    • v.19 no.4
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    • pp.38-46
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    • 2007
  • Surface properties of the plasma treated fabric were changed while maintaining its bulk properties. Surface of plasma treated fabric take charge of enhanced adhesion by surface etching, surface activity. The water repellency coating Poly(Ethylene Terephthalate) fabric was treated with atmospheric pressure plasma using various parameters such as Argon gas, treatment time, processing power. Morphological changes by atmospheric pressure plasma treatment were observed using field emmission scanning electron microscopy(FE-SEM) and the zeta-potential measurement, contact angle measurement equipment. At the atmospheric pressure plasma treatment time of 150 sec, the power of 800W, the best wettability and peel strength were obtained. And we confirmed the possibility of industrial application by using atmospheric plasma system.

Thermally/Dynamically Stable Superhydrophobic ZnO Nanoparticles on Various Substrates

  • Lee, M.K.;Kwak, G.J.;Yong, K.J.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.360-360
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    • 2011
  • We demonstrated the fabrication method of superhydrophobic nanocoating through a facile spin-coating and the chemical modification. The resulting coating showed a tremendous water repellency with a static water contact angle (CA) of 158$^{\circ}$ and a hysteresis of 1$^{\circ}$. The number of ZnO nanoparticle (NP) coating cycles affected on the surface roughness, which is key role for superhydrophobic surface, and thus the CA can be modulated by changing the ZnO NP coating cycles. The CA can be controlled by changing the carbon length of Self-Assembled Monolayers(SAM). This simple ZnO coating is substrate-independent including flexible surfaces, papers and cotton fabrics, which can effectively be used in various potential applications. We also observed the thermal and dynamic stabilities of SAM on ZnO nanoparticles. The superhydrophobicic surface maintained its superhydrophobic properties below 250$^{\circ}C$ and under dynamic conditions.

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Chemically Modified Superhydrophobic Zinc Oxide nanoparticle surface

  • Lee, Mi-Gyeong;Gwak, Geun-Jae;Yong, Gi-Jung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.448-448
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    • 2011
  • We investigated the fabrication method of superhydrophobic nanocoating prepared by a simple spin-coating and the chemisorption of fatty acid. The resulting coating showed a tremendous water repellency (static water contact angle = $154^{\circ}$) and the water contact angle can be modulated by changing the number of deposition cycles of ZnO and the carbon length of Self-Assembled Monolayers (SAM). Varying the number of deposition cycles of ZnO controlled the surface roughness, and affected to the superhydrophobicity. This simple coating method can be universally applicable to any substrates including flexible surfaces, papers and cotton fabrics, which can effectively be used in various potential applications. We also observed the thermal and dynamic stabilities of SAM on ZnO nanoparticles. The superhydrophobicic surface maintained its superhydrophobic properties below $250^{\circ}C$ and under dynamic conditions.

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