Showing papers on "Precipitated silica published in 1993"

Compositions and methods for polishing and planarizing surfaces

Abstract: An abrasive composition for use in polishing or planarizing the surface of a work piece is provided comprising about 30 to 50 percent of cerium oxide; about 8 to about 20 percent of fumed silica; and about 15 to about 45 percent of precipitated silica. Methods using the composition to polish or planarize the surfaces of work pieces, as well as products produced by such methods, are also provided.

Effect of the metal oxide loading on the activity of silica supported MoO3 and V2O5 catalysts in the selective partial oxidation of methane

Abstract: Precipitated silica catalysts loaded with either MoO3 (0.2–4.0 wt%) or V2O5 (0.2–5.3 wt%) have been studied in the selective partial oxidation of methane to formaldehyde with molecular oxygen at 520 °C. The functionality of the SiO2 surface towards the formation of HCHO is significantly promoted by V2O5, while it is depressed by the MoO3.

Low temperature method of making very high structure silica

Abstract: Precipitated silica gels having high surface areas and low oil absorption values are produced by a low temperature synthesis precipitation process. The precipitated silicas have unique flatting characteristics and are additionally useful as conditioning agents for food and salt and in dentifrice formulations.

Preparation of γ-Fe2O3-containing silica glasses by the sol-gel process

Abstract: We report the preparation of γ-Fe 2 O 3 -precipitated silica glasses by a sol-gel process from Si(OC 2 H 5 ) 4 and Fe(NO 3 ) 3 .9H 2 O

Aqueous suspensions of precipitated silica with anionic dispersant and aluminum compound

Abstract: Stable aqueous suspensions of precipitated silica, well adopted as coatings for the papermaking industry, include an aqueous suspension of a slaked precipitated silica filter cake and an effective amount of a stabilizer therefor, which stabilizer contains (a) aluminum or an aluminum compound, and (b) an anionic dispersing agent.

Granular bitumen coated with precipitated silica

Abstract: Bitumen granulate containing from 0.5 to 15% by weight, preferably from 6.1 to 15% by weight, of a powdering and separating agent such as, for example, synthetic silica or carbon black is produced by atomizing hot, liquid bitumen in a spray mixer and at the same time introducing the powdering and separating agent into the spray mixer by way of the stream of cold air.

Particulate amorphous precipitated silica

Abstract: A statistically large population of particles of amorphous precipitated silica is substantially free of particles of amorphous precipitated silica which are retained on a 20 mesh sieve screen, and is characterized by at least 90 percent by weight of said particles of said population being retained on a 200 mesh sieve screen. Such a population may be produced by cracking amorphous precipitated silica particles between the textured rolls of at least one roll pair.

Purification and recovery of lipoprotein cholesterol

Abstract: Disclosed is an improved process for the recovery of cholesterol rich fractions from mammalian serum or plasma. The process involves adsorbing the fraction on precipitated silica gel agglomerates which are then separated from the serum or plasma whereupon the adsorbed cholesterol rich fraction is eluted from the silica and recovered.

Flexible magnetic recording media having a backing coating containing a polyurethane resin having a phosphate group and precipated silica

Abstract: In flexible magnetic recording media consisting essentially of a web-like nonmagnetic substrate, the magnetic layer is applied to one main side of the web-like substrate and a backing coating formed on the opposite main side of the substrate from a polymeric binder and nonmagnetic fillers as well as supporting pigments, the backing coating contains a precipitated silica treated on the surface with a phosphate-containing polyurethane.

Heat- and/or sound insulating board and method of making the same

Abstract: Thermal- and/or sound-insulating board characterised in that it comprises a dried mixture: - of precipitated silica consisting of a filter cake originating from the precipitating reaction and crumbled, - a reinforcing agent, - optionally, an opacifying agent. Processes for obtaining the said board from a filter cake originating from the precipitation reaction of a silica.

Agricultural wettable powder composition

Abstract: PURPOSE:To provide the subject composition composed of an agricultural active component, a surfactant and a specified carrier for reducing coagulation and precipitation of the active component as low as possible, remarkably improved in shelf life and workability in preparation and application. CONSTITUTION:The objective composition contains (A) an agricultural active component, (B) a carrier composed of precipitated silica having surface hydroxyl group density and (C) a surfactant (e.g. alkylarylsulfonate). As the component (A), a compound having <=70 deg.C melting point, e.g. 0,0- dimethyl-0-[3-methyl-4-(methylthio)phenyl] thiophosphate is preferable from the viewpoint of preventing precipitation and coagulation. The component (B) is obtained, e.g. by heating precipitated silica prepared by the known method at 700-1000 deg.C for 10-20min.

A Study on Structural Force in Silica Suspensions.

Abstract: The aqueous suspensions of precipitated silica exhibit anomalous stability due to the structural forces not considered in the classical DLVO theory. The magnitudes of the structural energies have been estimated using an extended DLVO theory, in which the structural energy is expressed as a double-exponential function. The result shows that the structural force decreases with increasing NaCl concentration as opposed to the structural forces observed in rutile and mica. It is believed that an inherent water structure exists on silica surfaces and develops a steric repulsion, while the water structures on rutile and mica are gradually formed as hydrated cations adsorb onto each solid surface. In this regard, the hydration force observed with silica can be referred to as “primary hydration force”, while those observed with rutile and mica can be referred to as “secondary hydration force”. By incorporating the concept of cation bridging in silica coagulation, it has been shown that the opposite effect of cations on the structural forces in silica and rutile can be explained consistently.

Formation of Ultrathin Polystyrene Films in Adsorbed Surfactant Bilayers on Silica

Abstract: Adsorbed surfactant bilayers on silica are proposed as the reaction site for the formation of ultrathin polystyrene films. Results from the polymerization of styrene in cetyl trimethyl ammonium bromide bilayers show effective conversion of adsolubilized monomer to polymer. The process has been demonstrated for a variety of precipitated silica substrates and for two types of initiation schemes. The polymer formed has been extracted and characterized using PA-FT1R, NMR, UV, and GPC. The molecular weight of polymer formed has also been investigated with respect to polymerization time.