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62.
硅烷接枝聚乙烯储存稳定性的研究 总被引:3,自引:0,他引:3
利用熔体流动速率测定仪进行了硅烷接枝聚乙烯的水解缩合交联反应的加速试验,发现该反应对水分浓度为一级反应,反应的表现活化能42kJ/mol,由此可推算A组份的保存期。当催化剂存在时,水解缩合反应明显加快,这时的表观活化能降到20kJ/mol。 相似文献
63.
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65.
三(三甲基硅氧基)甲基丙烯酰氧丙基硅烷的合成研究 总被引:3,自引:0,他引:3
用3种方法合成了三(三甲基硅氧基)甲基丙烯酰氧丙基硅烷,通过核磁共振氢谱和红外吸收光谱确证其结构,其中一步法产率可达60%以上,纯度可达98%以上,与文献报道方法相比,产率提高了10%,成本降低了30%。 相似文献
66.
Wieland Tyrra Dieter Naumann Sigrid Buslei Mikhail M. Kremlev 《Journal of fluorine chemistry》2007,128(7):813-817
A temperature range of −18 °C to room temperature was found to be effective for selective fluoride-mediated cross-coupling reactions of trimethyl(perfluoroalkyl)silanes, Me3SiCF3 and Me3SiC2F5, and alkyl halides, RX (X = Br, I) in the absence of any catalyst. 相似文献
67.
Total energy calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and ultrasoft pseudopotential approximation and an analysis tool of atom‐resolved density of states (ADOS) have been used to investigate (1) the energetic profiles for the possible initial dissociative adsorption of XH4 (X?Si and Ge) onto the Si(100)? (2 × 2) surface to evaluate their reactivity and (2) the effect of surface electronic states of Si(100)? (2 × 2) on gaseous molecular precursors XH4 (X?Si and Ge) during initial dissociative adsorption to understand the factors governing their reactivity. Our calculated lower‐energy barrier for initial dissociative adsorption of GeH4 is due to the forming of stronger bond of Si? H between H within GeH4 and buckled‐down Si atom on the Si(100)? (2 × 2) surface accompanying the larger extent of unbuckling of the buckled Si?Si dimer on the Si(100)? (2 × 2) surface at the transition state. Our evaluated better reactivity for GeH4 than SiH4 (a factor of around 14.6) is slightly larger than observed higher reactivity for GeH4 than SiH4 (a factor of between 2 and 5 depending on the incident kinetic energy) employed supersonic molecular bean techniques. Finally, our calculated ADOS indicate that the surface electronic states of buckled Si?Si dimer on the Si(100)? (2 × 2) surface energetically favorably participate in the transition state during GeH4 initial dissociative adsorption to reduce the energy barrier, i.e., enhance its reactivity, in comparison with SiH4 initial dissociative adsorption onto the Si(100)? (2 × 2) surface under the same reaction conditions. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
68.
Crystal Structure of Bis[lithium-tris(trimethylsilyl)hydrazide] and Reactions with Fluoroboranes, -silanes, and -phospanes Tris(trimethylsilyl)hydrazine reacts with n-butyllithium in n-hexane to give the lithium-derivative 1 . The reaction of 1 with SiF4, PhSiF3, BF3 · OEt2, F2BN(SiMe3)2 and PF3 leads to the substitution products 2–6 . The 1,2-diaza-3-bora-5-silacyclopentane 7 is formed by heating (Me3Si)2N? N(SiMe3)(BFNSiMe3)2 ( 5 ) at 250°C. In the reaction of (Me3Si)2N? N(SiMe3)PF2 ( 6 ) with lithiated tert.-butyl(trimethylsilyl)amine the hydrazino-iminophosphene (Me3Si)2N? N = P? N(SiMe3)(CMe3) ( 8 ) is obtained. In the molar ratio 2:1 1 reacts with SiF4 and BF3 · OEt2 to give bis[tris(trimethylsilyl)hydrazino]silane 9 and -borane 10 . 相似文献
69.
Characterization of electron-beam-modified surface coated clay fillers and their influence on physical properties of rubbers 总被引:3,自引:0,他引:3
Sudip Ray Anil K. Bhowmick K. S. S. Sarma A. B. Majali V. K. Tikku 《Radiation Physics and Chemistry》2002,65(6):627-640
A novel process of surface modification of clay filler has been developed by coating this with an acrylate monomer, trimethylol propane triacrylate (TMPTA) or a silane coupling agent, triethoxy vinyl silane (TEVS) followed by electron beam irradiation. Characterization of these surface modified fillers has been carried out by Fourier-transform infrared analysis (FTIR), electron spectroscopy for chemical analysis (ESCA), wettability by dynamic wicking method measuring the rise of a liquid through a filler-packed capillary tube and water flotation test, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Presence of the acrylate and the silane coupling agent on the modified fillers has been confirmed from FTIR, ESCA, and EDX studies, which has also been supported by TGA studies. The contact angle measurement by dynamic wicking method suggests improvement in hydrophobicity of the treated fillers, which is supported by water flotation test especially in the case of silanized clay. However, XRD studies demonstrate that the entire modification process does not affect the bulk properties of the fillers. Finally, both unmodified and modified clay fillers have been incorporated in styrene butadiene rubber (SBR) and nitrile rubber (NBR). Rheometric and mechanical properties reveal that there is a definite improvement using these modified fillers specially in the case of silanized clay compared to the control sample, probably due to successful enhancement in interaction between the treated clay and the base polymer. 相似文献
70.
Siddharth V. Patwardhan Christina Raab Nicola Hüsing Stephen J. Clarson 《Silicon Chemistry》2005,2(5-6):279-285
Following recent investigations on the role of synthetic and biological macromolecules in silicification and biosilicification, we report here the bioinspired synthesis of silica structures under ambient conditions and neutral pH mediated by two synthetic macromolecules. In this research ethylene glycol modified silane (EGMS) was used as the silica precursor. The macromolecules used were either poly(allylamine hydrochloride) (PAH) or poly-l-lysine (PLL), both being cationically charged at neutral pH in an aqueous medium. Mild conditions that constitute the bioinspired or biomimetic synthesis were used to compare the behaviour of the EGMS to other silica precursors. The products were characterised by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectroscopy (FTIR). The formation of well-defined spherical silica particles (for both PAH and PLL) and hexagons (for PLL only), was shown by electron microscopy. In addition, it was also found that these macromolecules were incorporated into the silica products, thus fulfilling the dual role of catalysts and structure directing agents in a similar fashion to that described in the literature for the formation of (bio)silica, as facilitated by (bio)macromolecules.This paper is dedicated to Mike Owen on occasion of his winning the DeBruyn medal, the first silicon chemist to do so. 相似文献