• Title/Summary/Keyword: Silanes

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Synthesis of poly(dialkyl or monoalkyl)silanes as silicon carbide precursors for ceramic matrix composites (탄화규소 선구물질로서의 폴리(디알킬 또는 모노알킬)실란들의 합성과 세라믹 복합체 응용)

  • Lee, Gyu-Hwan
    • Analytical Science and Technology
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    • v.26 no.1
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    • pp.27-33
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    • 2013
  • Polyalkylsilanes such as poly(dialkyl)silanes and poly(monoalkyl)silanes were synthesized by sonochemical dechlorination-condensation method from (dialkyl or monoalkyl)chlorosilanes with sodium metal. Those polyalkylsilanes were analyzed for the properties such as thermal behaviors from TGA analysis and obtained ceramic yields of 10-20% for poly(dialkyl)silanes and 40-60% for poly(monoalkyl)silanes. Ceramic composite discs were prepared by the combined mixture of polyalkylsilanes and SiC powder and were tested by TGA and analyzed by SEM and XRD for the application as binder for ceramic composite precursors.

Reaction Scheme on the Direct Synthesis of Methylchlorosilanes (Methylchlorosilanes의 직접 생산 반응에서 반응기구)

  • Kim, Jong Pal;Lee, Kwang Hyun
    • Korean Chemical Engineering Research
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    • v.56 no.2
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    • pp.291-296
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    • 2018
  • Direct synthesis of methylchlorosilanes was developed by Rochow with addition of copper on the silicon surface as a catalyst and many research were followed. Most of research were focused on the increase of reaction activity through addition of promoters and concentrated on the increase of selectivity of DMDC. However, there are very few studies about the reaction mechanism. Although formation of DMDC was explained in literature, formation of other silanes were not mentioned at all. This reseach focused on the explanation about formation of all silanes obtained during direct reaction and TPD. Reaction paths were proposed by means of dissociative adsorption of methyl chloride and spillover of surface Cl and H. Surface silicon sites were considered as $=SlCl_2$ and $=Sl(CH_3)Cl$. The synthesis of all methylchlorosilanes were explained by the adsorption of methyl group on the silicon sites and by the surface diffusion of nearby Cl and H. The proposed reaction mechanism explains the formation of all silanes during the reaction and also during the TPD process.

Deoxygenation of ${\beta}$-Aryl-${\alpha}$,${\beta}$-Epoxy Silanes to Vinylsilanes by Magnesium-Magnesium Halide

  • Kang, Kyung-Tae;Park, Chun-Yi;Kim, Joung-Sook
    • Bulletin of the Korean Chemical Society
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    • v.13 no.1
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    • pp.48-53
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    • 1992
  • The reactions of ${\beta}-aryl-{\alpha},{\beta}-epoxy$ silanes with magnesium bromide or magnesium iodide in the presence of excess magnesium in ether at room temperature afforded vinylsilanes in 18-100% yields. E-Vinylsilanes were predominant over Z-isomers (> 80%) regardless of the stereochemistry of ${\alpha},{\beta}-epoxy$ silanes.

Dehydropolymerization of Silanes to Polysilanes Catalyzed by Organometallic Complexes (유기금속 착물 촉매에 의한 실란의 탈수소중합 반응)

  • Woo, Hee Gweon;Song, Sun Jung
    • Journal of the Korean Chemical Society
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    • v.41 no.9
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    • pp.502-517
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    • 1997
  • This review deals with (1) the catalytic systems and mechanisms for the dehydropolymerization of silanes to polysilanes, (2) the dehydropolymerization of versatile silanes, (3) the preparation of polysilane derivatives, and (4) the applications of catalytic dehydropolymerizing systems to ceramics. The efforts to maximize the catalytic efficiency of group 4 metallocenes were introduced. Finally, the future of this dehydropolymerizing techniques of silanes was foreseen.

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Photopolymerization of Methacrylic Acid with Secondary Silanes

  • 우희권;박선희;홍란영;강행구;함희숙
    • Bulletin of the Korean Chemical Society
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    • v.17 no.6
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    • pp.532-535
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    • 1996
  • The bulk photopolymerization of methacrylic acid (MA) with secondary silanes such as PhMeSiH2 and Ph2SiH2 gave poly(MA)s possessing the secondary silyl moiety presumably as an end group. It was found that while the polymerization yields and intrinsic viscosities decreased, the TGA residue yields and the relative intensities of SiH IR stretching bands increased with increasing mole ratio of the secondary silane over MA. The sterically less bulky silane PhMeSiH2 produced poly(MA)s with somewhat higher molecular weights and with similar TGA residue yields compared with the sterically bulkier silane Ph2SiH2. The secondary silanes seem to significantly influence on the photopolymerization of MA as both chain initiation and chain transfer agents.

Preparation and Characterization of Chemically Modified Wood Flour Reinforced Phenol-formaldehyde Composites

  • Nam, Byeong-Uk;Mun, Jun-Yeong
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.1
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    • pp.1-5
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    • 2018
  • Wood Polymer Composites(WPC) have attracted significant attention because of ecological and environmental concerns. However, the structure of Wood Flour containing many hydroxyl groups(-OH) reduces the interface adhesion to Phenol-formaldehyde(PF) and it decreases the mechanical properties of the PF/Wood Flour Composites. The present work involves the modification of Wood Flour using silanes reinforced with Phenol-formaldehyde to enhance the mechanical properties of the composites. The spectroscopic properties of the composites were analyzed using FT-IR, XPS(X-ray Photoelectron Spectroscopy) and the mechanical properties i.e., tensile strength, flexural strength and impact strength were studied. We confirmed the modification effect of silanes by spectroscopic analysis, and the mechanical properties of the composites using wood flour modified by silanes were significantly improved.

The Adhesion Promotion of Glass Fiber Reinforced Composite Using Methacrylate Functional Silanes (메타아크릴레이트 실란을 이용한 유리섬유 강화복합재료의 물성향상)

  • Jang, Jyong-Sik
    • Applied Chemistry for Engineering
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    • v.1 no.2
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    • pp.133-139
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    • 1990
  • Methacrylate functional silanes with different methylene spacer groups have been synthesized and the orientation effect and absorption behavior of these silane coupling agent were investigated by Fourier transform infrared spectroscopy(FT-IR). The mechanical properties of glass bead/polyester composites are found to be dependent on the spacer group of treated silane coupling agent. The absorption rate of the silane coupling agent onto the fumed silica surface decreases with increasing the number of the methylene spacer in methacrylate functional silanes. Silane molecules containing long spacer groups are adsorbed onto silica slightly bowed with respect to the substrate surface. The relationship between silane molecular structure and mechanical properties of polymer composites is also investigated in order to improve hot/wet properties of glass fiber/polyester composites.

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The Crystalline Quality of Si Films Prepared by Thermal- and Photo-CVD at Low Temperatures

  • Chung, Chan-Hwa;Rhee, Shi-Woo;Moon, Sang-Heup
    • Journal of the Korean Vacuum Society
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    • v.4 no.S1
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    • pp.34-39
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    • 1995
  • Various silicon films were prepared by thermal- and UV photo-CVD processes. The reactants were SiH4, Si2H6, SiH2F2, SIF4, and H2. Silicon films grown at temperatures below $500 ^{\circ}C$ were either amorphous or crystalline depending on the process conditions, and the growth rates ranged between 5 and $80\AA$min. Crystallinity of the film was improved even at $250^{\circ}C$ when the film was grown by photo-CVD using fluoro-silanes as the reactants. Analysis of the film by RBS, SIMS, XRD, and ex-situ IR indicated that substrate surface was contaminated by oxygen and other impurities when the reactants contained neither hydrogen nor fluoro-silnanes, but when fluoro-silanes were used as reactants the silicon film was highly crystalline.

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Interfaces Between Rubber and Metallic or Textile Tire Cords

  • Ooij Wim J. Van;Luo Shijian;Jayaseelan Senthil K,
    • Elastomers and Composites
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    • v.34 no.4
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    • pp.299-314
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    • 1999
  • Bonding metal and textile components to rubber has always posed a problem. In this paper, an attempt had been made to modify textile and metal surfaces for bonding with rubber. The metal surfaces were modified using silane coupling agents and textile fibers were modified using plasma polymerization techniques. Some results on adhesion of metals to a range of sulfur-cured rubber compounds using a combination of organofunctional silanes are given here. The treatment was not only effective for high-sulfur compounds but also for low-sulfur com pounds as used in engine mounts and even for some semi-EV compounds. Coatings of plasmapolymerized pyrrole or acetylene were deposited on aramid and polyester tire cords. Standard pull-out force adhesion measurements were used to determine adhesion of tire cords to rubber compounds. The plasma coatings were characterized by various techniques and the performance results are explained in an interpenetrating network model.

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