Fumed silicon dioxide

Aerosil Cab-O-Sil Cab-O-Sil MSP-, colloidal silica fumed silica light anhydrous silicic acid silicic anhydride silicon dioxide fumed Wacker HDK. 

Chemical Name Silicon dioxide, fumed amorphous... 

Silicon Dioxide occurs in nature as agate, amethyst, chalcedony, flint, quartz, sand, and tridymite. Silicon dioxide is obtained by acid precipitation from a sodium silicate solution to yield veiy fine particles. If silicon dioxide is obtained by the addition of sodium silicate to a mineral acid, the product is termed a silica gel. The pharmaceutical industry uses colloidal silicon dioxide, which is a submicroscopic fumed silica prepared by the vapor phase hydrolysis of a silica compound, such as silicon tetrachloride. Other names for colloidal silicon dioxide include light anhydrous silicic acid, silicic anhydride, and silicon dioxide fumed. Colloidal Silicon Dioxide NF must meet the following standards ... 

Fumed Silica. Today colloidal silica (fumed silica) is the most common thixotropic agent in epoxy resins. Fumed silica, an amorphous silicon dioxide, is a versatile, efficient additive used for flow control and thixotropy. Fumed silica has long been the dominant thixotrope employed in the adhesive and sealant industry. 

Assay for Silicon Dioxide Transfer about 400 mg of sample, accurately weighed, into a beaker, add 5 mL of water and 10 mL of perchloric acid, and heat until dense, white fumes of perchloric acid evolve. 

Silicon Dioxide occurs as an amorphous substance that shows a noncrystalline pattern when examined by X-ray diffraction. It is produced synthetically, either by a vapor-phase hydrolysis process, yielding fumed silica, or by a wet process, yielding precipitated silica, silica gel, colloidal silica, or hydrous silica. Fumed silica is produced in an essentially anhydrous state, whereas the wet-process products are obtained as hydrates or contain surface-adsorbed water. 

Fumed silica occurs as a white, fluffy, nongritty powder of extremely fine particle size and is hygroscopic. The wet-process silicas occur as white, fluffy powders or as white, microcellular beads or granules and are hygroscopic or absorb moisture from the air in varying amounts. All of these forms of Silicon Dioxide are insoluble in water and in organic solvents, but they are soluble in hydrofluoric acid and in hot, concentrated solutions of alkalies. 

Commonly used lubricants are listed in Table 5. Talc is traditionally one of the most commonly used glidants, having the additional benefit of being an excellent antiadherent. The level of talc that can be added to a formulation is restricted by its hydrophobic nature, too high levels resulting in decreased wetting of the tablet and a subsequent reduction in the rate of dissolution. Fumed silicon dioxides are... 

Fumed silicon dioxide 0.1-05 and diluent Has small particle size and large surface area for... 

If a powder flows poorly, the vibrator can be used, but it also causes powder segregation and stratification. The addition of glidant (occasionally lubricant) in the powder mixtures can readily increase flowability at the low concerntration. Talc or fumed silicon dioxide is an example of a glidant. If this is not sufficient to improve the flow, other means of flow improvement are necessary. There are two main factors that affect powder flow particle size and particle shape. The more spherical a particle is, the better it flows. Small particles are very cohesive and hence do not flow well, but increasing the particle size will improve flow. With the aid of spray drying or spheronizers, particles become spherical. 

Fumed silica appears as a fluffy white powder characterized by an extremly low bulk density down to the range of about 20-50 g f. In contrast, the submicron fumed silica particle consists of amorphous silicon dioxide and, hence, its true density is about 2200 g 1 ... 

The chemistry of a finely divided solid with high surface area is at the borderline between molecular chemistry and physics of solid surfaces. The surface of a finely divided amorphous silica may be understood as a two-dimensional projection of the three-dimensionally linked silicon dioxide tetrahedra. By this the chemistry of the fumed silica surface is dominated by Si-O-Si units and, in particular, dangling surface Si-0 bonds, which will create silanol groups under the influence of humidity at ambient temperature. 

Due to its high surface area, surface chemistry and physics dominate the properties of fumed silica. The O—Si-O being 0.3 to 0.4 nm let estimate about only 20 silicon dioxide units spanning the diameter of a primary particle of amorphous silica. Fumed silica therefore has an extremely high surface to bulk ratio up to about 10 %. This is why even bulk methods of chemical analysis are suitable to follow chemical reactions on its surface elemental analysis, IR or NMR methods, etc. 

Fumed silica is a highly dispersed silicon dioxide of large industrial importance and a wide spectrum of applications. Due to its production in a flame process fumed silica exhibits a smooth and nonporous particle surface. Additionally to its high surface area fumed silica bears isolated and statistically distributed surface silanol groups that render this product hydrophilic. A most important technical reaction, therefore, is the silylation and hydrophobization of the hydrophilic surface. 

SYNS ACTICEL AEROSIL AMORPHOUS SILICA DUST AQUAFIL CAB-O-GRIP II CAB-O-SIL CAB-O-SPERSE CATALOID COLLOIDAL SIUCA COLLOIDAL SILICON DIOXIDE DAVISON SG-67 DICALITE DRI-DIE PESTICIDE 67 ENT 25,550 FOSSIL FLOUR FUMFX) SILICA FUMED SILICON DIOXIDE O LUDOX NALCOAG NYACOL NA ACOL 830 NYACOL 1430 SANTOCEL SG-67 SIUCA, AMORPHOUS SILICIC ANHYDRIDE SIUCON DIOXIDE (FCQ SIUKILL VULKASIL... 

Colloidal silicon dioxide is a submicroscopic fumed silica with a particle size of about 15 nm. It is a light, loose, bluish-white-colored, odorless, tasteless, nongritty amorphous powder. 

Fe(N03)3 9 H2O, oxalic acid, K3[Fe(CN)6]. H2O, Triton -X-100 (nonionic surfactant), Cab-O-Sil (highly dispersed fumed silicon dioxide). 

The fumed silicon dioxides are perhaps the most effective glidants. These are materials with very small (10 nm) spherical particles that may achieve their glidant properties by rolling over each other under shear stress. They are available in a number of grades with a range of hydrophobic and hydrophillic forms. 

Aggregate, alumiiia (alumiiium oxide), cement raw mix, clay, dolomite, fluorspar, kaolin, light weight aggregate, lime, limestone, magnesia (magnesium oxide), pigments, silica (silicon dioxide), silica fume Products... 

CAB-O-SPERSE CATALOID COLLOIDAL SILICA COLLOIDAL SILICON DIOXIDE DICALITE DRI-DIE INSECTICIDE 67 FLO-GARD FOSSIL FLOUR FUMED SILICA FUMED SILICON DIOXIDE HI-SEL LO-VEL LUDOX NALCOAG ... 

In The Chemistry of Silica [1], Her used the term silica powders as a broad category encompassing silica gels, precipitated silicas, and fumed or pyrogenic silicas. These are all forms of synthetic amorphous silicon dioxide, a broad category that also includes another form — silica sols or coUoidal silica — that is not a powder, but rather a dispersion of discrete silica particles in a liquid medium. 

Colloidal silicon dioxide. See Silica, colloidal Silica, fumed... 

Fumaric acid, diallyl ester. See Diallyl fumarate Fumaric acid, dibutyl ester. See Dibutyl fumarate Fumaric resin. See Maleic resin Fumed silica Fumed silicon dioxide. See Silica, fumed Fural 2-Furaldehyde Furale. See Furfural... 

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