Silica-silane reaction

ZnO influences the characteristics of a compound twofold Primarily, ZnO influences the kinetics of the silica-silane reaction. Secondly, ZnO enhances the scorching behavior of a sulfur-containing coupling agent. This effect is clearly visible when looking at the G at 100% strain and the 300% modulus. 

W. Dierkes, Economic mixing of silica-mbber compounds Interaction between the chemistry of the silica-silane reaction and the physics of mixing, Ph.D. thesis, University of Twente, The Netherlands, 22 April 2005, ISBN 90-365-2185-8. 

The latter procedure has so far been applied successfully (/) to a large number of silicas suitable for column chromatography (60-200 mesh). Attempts to extend these techniques to thin-layer silicas have not been successful. In the case of silicas with calcium sulfate binder, experimental values of 5,. and St appear quite variable and do not agree with values that can be inferred from surface area, pore diameter, and chromatographic activity data. This suggests that calcium sulfate in some way interferes with the silica-silane reaction. For thin-layer silicas without binder, erroneously low values of S jSf are obtained. This is believed to be due to... 

Blume, A. (2011). Kinetics of the Silica-Silane Reaction. Kautschuk und Gummi Kunststoffe, 4, 38 3. 

The mixing of highly filled silica rabber is discussed with reference to the linking of a bifunctional organosilane to the sihca. The reaction mechanism is investigated for fotrr different silanes for the in-situ modification of sihca. A study is made of the silane reaction following the ethanol formation the influence of the dump temperature, the influence of silane concentration, the silica/silane reaction following the shear modulus tan tones, and consequences for compotmders. 23 refs. 

U. Gorl, A. Hunsche. Advanced investigations into the silica/silane reaction system. ACS, Rubb. Div. Mtg., Louisville, KY, Oct. 8-11,1996. Paper 76. 

U. Gorl, A. Hunsche, A. Mueller, H.G. Koban. Investigations into the silica/ silane reaction system. Rubb. Chem. TechnoL, 70,608-623,1997. 

The silanization reaction has been used for some time to alter the wetting characteristics of glass, metal oxides, and metals [44]. While it is known that trichlorosilanes polymerize in solution, only very recent work has elucidated the mechanism for surface reaction. A novel FTIR approach allowed Tripp and Hair to prove that octadecyl trichlorosilane (OTS) does not react with dry silica. 

Network Formation with Silica The Silanization Reaction.802... 

Silica compounds are generally processed in conventional internal mixers, preferably with intermeshing rotors. These mixers are designed and optimized for carbon black-fiUed compounds in which mixing is based only on physical processes. When a silica-silane reinforcing system is used, additionally a chemical reaction, the sUanization, occurs. One of the main influencing factors of the silanization reaction is the concentration of ethanol in the compound as well as in the mixer [25,26]. As the silanization finally reaches an equilibrium, low concentrations of ethanol in the compound are expected to enhance the reaction rate. 

High operation temperature (limited by scorch phenomena) in order to raise the speed of the silane reaction with silica and the diffusion coefficient of ethanol... 

The efficiency of the silanization reaction is increased by aU measures enhancing devolatilization of ethanol from the silica compound in the mixer. One possible measure is the reduction of the ethanol concentration in the void space of the mixer, thus increasing the driving force for mass... 

In this part, we wish to focus on the study of two types of silanes. Aminoorganosilanes are special members of the alkoxysilanes group. They carry the catalyzing amine function, required for chemical bonding with the silica surface, inside the molecule. This makes them more reactive than other organosilanes and reduces the complexity of the liquid phase reaction system to be studied. Only three components, silica, silane and solvent, are present. Furthermore there is a large interest in the reaction mechanism of silica gel with APTS, since this aminosilane is the most widely used compound of the organosilane family. 

FIGURE 6-2. (a) Types of silanols on the surface of silica, (b) Reaction of various chlorosubstituted silanes with silica gel. 

Surface Modification with Chlorosilanes. Chlorosilanes are volatile and very sensitive to the presence of trace amounts of water. Vapor-phase silanization reactions with rigorous control of the absence of water show that Cl SiMe4-n-type chlorosilanes react with aerosil (nonporous microparticulate silica) as... 

A typical RPLC column is packed with porous silica beads. The pore sizes have a length scale in the range 50-100 A. The silica substrate is derivatized by a silanization reaction which attaches alkanes to hydroxyl groups on the surface. Chains of length 8-18 carbon atoms are utilized, with the Cjg case being common. Surface densities up to about 50% of close packing are typical. The mobile phase most often contains a cosolvent, such as methanol or acetonitrile, in addition to water. 

As noted earlier, three types of functional silanol groups exist on the silica surface isolated hydroxyl groups, geminal groups (two -OH groups on one Si atom), and vicinal groups (see Figure 9.6). The silanization reaction is illustrated in Eq. (9.5). 

CAS 68611-44-9 EINECS/ELINCS 271-893-4 Synonyms Dimethyidichlorosilane, reaction prods, with silica Silane, dichlorodimethyl-, reaction prods, with silica Uses Rheology control agent, reinforcing agent, free-flow agent for adhesives, coatings,... 

Considering the same filler content, the compound with silanized silica presents a maximum G" value lower (70 MPa) than that with non silanized silica. This result can be understanding, in the case when the silica surface activity decrease, due to the silanization reaction. As consequence of the silanization, the physical interaction of the less polar filler surface with epoxidized SBR, or the cross section of the chemical bond became reduced. Both mechanisms cause a decrease in the volume... 

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