Small Amounts Of Silane Research Articles

Improving steel passivation with aqueous solutions of [3-(2-Aminoethylamino)propyl]trimethoxysilane

It is shown by means of electrochemical measurements that small amounts of silane are capable of improving the protective properties of sodium salts of different organic carboxylates in the passivation of lowcarbon steel. The adsorption of sodium oleoylsarcosinate on both oxidized and reduced steel surfaces is studied by means of ellipsometry. It is shown that the passivation of low-carbon steel with a mixture of silane and oleoylsarcosinate at a ratio of 3 : 1 is an efficient method of protection under severely humid atmospheric conditions.

Modification of bentonite by combination of reactions of acid-activation, silylation and ionic exchange

ObjectiveThe aim of this study is to analyze different strategies of modification of bentonite (Bent) combining reactions of cationic exchange, silylation and acid activation. MethodsSix samples of modified bentonite were prepared: silylated bentonite (S-Bent), acid-activated bentonite (A-Bent), exchanged clay (E-Bent), silylated and acid-activated clay (S–A-Bent), exchanged and acid-activated clay (E–A-Bent), and exchanged, silylated and acid-activated bentonite (E–S–A-Bent). To study the effectiveness of the different treatments, X-ray diffraction analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy and water absorption tests were performed. ResultsThe silylated bentonite presented a significant reduction in the equilibrium water uptake percentage with respect to the unmodified clay, even when small amounts of silane were incorporated to the clay. On the other hand, no significant changes in the organic content were obtained when the silylation reaction was performed on previously acid-activated bentonite. When a sample of silylated and activated bentonite was further modified by cationic exchange reaction, it was found that the previous treatments allowed increasing the uptaken amount of surfactant cations during the exchange reaction. In fact, the combination of the three treatments (acid-activation, silylation and cationic exchange) gave place to the modified bentonite with the biggest basal spacing and the lower equilibrium water uptake percentage. SignificanceThe results obtained in the present study reveal the potential usefulness of the E–S–A-Bent sample as promising filler for the formulation of clay polymer nanocomposites. Work is in progress in this direction.

Polylactide‐recycled wood fiber composites

AbstractPolylactide (PLA)‐recycled wood fiber (RWF) composites with a small amount of silane were compounded using a kinetic‐mixer and molded using an injection molding machine. The molded PLA‐RWF composites were characterized using gel permeation chromatography, scanning electron microscope, X‐ray diffraction, differential scanning calorimeter, tensile testing machine, and a dynamic mechanical analyzer. As observed in the stress–strain plots, the amount of necking before fracture decreased with an increasing RWF content. Similarly, the strain‐at‐break also decreased with the RWF content. The tensile strength remained the same irrespective of the RWF content. Both the tensile modulus and the storage modulus of the PLA‐RWF composites increased with the RWF content. The degree of crystallinity of the PLA increased with the addition of RWF. No reduction in the number–average molecular weight (Mn) was observed for pure PLA and PLA‐10%RWF‐0.5%Silane composites after injection molding; however, substantial reduction in Mn was found in PLA‐20%RWF‐0.5%Silane composites. Finally, a theoretical model based on Halpin–Tsai empirical relations is presented to compare the theoretical results with that of the experimental results. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Mechanical and physical properties of amorphous carbon-based alloys

Silane and nitrogen were added in the gas phase in a technique suitable for the deposition of a-C and a-C:H films, even in the absence of an external bias. It has been shown that nitrogen dehydrogenates the films and weakens CH bonds, while a small amount of silane is sufficient to achieve high values (up to 40 GPa) of hardness, as measured by nanoindentation of thick films. This result has to do with the kinetics of deposition and not the alloying itself. Preliminary results concerning a new alloy (a-C:H:Si:N) are discussed too.

The counterflow diffusion flame burner: A new tool for the study of the nucleation of refractory compounds

This paper describes the development of the counterflow diffusion flame burner into a tool which provides great promise as a technique for the study of the nucleation from the vapor phase of refractory compounds such as SiO 2, Al 2O 3, and other metal oxides. This burner produces a flame which is flat, stable, and rectangular in shape, with temperature and species-concentration distributions which are uniform in the horizontal plane. Thus, concentrations and temperatures can be measured spectroscopically. Hydrogen (diluted in argon) and oxygen (diluted in argon) have been used as the primary fuels and oxidants. Small amounts of appropriate gases, e.g., silane, are added to the fuel stream. Light scattering measurements indicate that an avalanche of nucleation occurs when the silane flow rate is increased beyond a critical value (e.g., 2.3 cm 3/min). The temperatures and the partial pressures of SiO and O 2 were measured. Assuming chemical equilibrium in the vapor phase, the SiO 2 partial pressure and the SiO 2 supersaturation were calculated. The H 2 O 2 flame changes color from pale-blue to a whitish pale-yellow when small amounts of silane are introduced into the flame. Increasing the silane flow rates makes this flame brighter and brighter. When the silane flow rate is increased sufficiently (e.g., to 9.3 cm 3/min), a second flame, thin and orange in color, appears on the H 2-side of the H 2 O 2 flame zone. Between the two flames there is always a dark space. The peak in light scattering intensity always occurs in the middle of this dark space.

Survey of selected hydrides as doping agents for a hydrogen-atmosphere flame-ionization detector

The hydrogen-atmosphere flame-ionization detector for gas chromatography exhibits a selective and enhanced response for metal containing compounds when its atmosphere is doped with small amounts of silane. In this study, response characteristics of the flame were investigated for a variety of organic compounds when the hydrogen atmosphere was doped with small amounts of methane, silane, germane, or phosphine. Responses of pure hydrocarbons and compounds containing F, Cl, O, S, N, P, As, Sb, Si, or Ge were either unaffected by the addition of doping agents, or their variations were not considered analytically significant. As expected, compounds of Fe, Sn and Pb exhibited enhanced responses with silane doping. Mo and W compounds showed increased ionization with methane. Several compounds increased response with the introduction of germane, but noise also increased such that no gain in signal-to-noise ratio was obtained. Phosphine proved to be the doping agent with the most potential. Response intensities for compounds containing Fe, Sn, Pb, Mo and Sb appeared analytically useful, but more significant, was the fact that the peaks were negative. Thus, it appears that a potential exists for the development of a phosphine-doped detector in which compounds not containing elements of interest would produce deminutive positive peaks while metal containing compounds would respond with enhanced negative peaks. Further studies on this mode of operation are recommended.