Showing papers on "Precipitated silica published in 1992"

Surface vibrational modes of silanol groups on silica

Abstract: Infrared spectroscopy has been used to study the vibrational modes associated with free (isolated) silanol groups on an aerosil silica and a precipitated silica which have been activated in vacuum in the temperature range from 450 to 800 o C. Both silicas exhibit two Si-O-H angle deformation modes at 760 and 840 cm -1 , indicative of two types of isolated silanol species, called type I and II, respectively

Filler—Elastomer Interactions. Part IV. The Effect of the Surface Energies of Fillers on Elastomer Reinforcement

Abstract: Carbon black N110 and a precipitated silica, which have comparable surface area and structure, were selected as model fillers to study the effect of filler surface energies on rubber reinf...

Process for the preparation of precipitated silica, precipitated silicas thus obtained, and their use in the reinforcement of rubbers

Abstract: A process for the preparation of precipitated silica having an aptitude for dispersion and improved reinforcing properties. The invention also relates to new silicas which exist in the form of granules, powder or substantially spherical balls, these silicas being characterised in that they have both a BET specific surface and a CTAB specific surface of between 140 and 200 m /g, and in that the porous volume constituted by the pores with diameters between 175 ANGSTROM and 275 ANGSTROM represents at least 50 % in the case of powders and balls, and at least 60 % in the case of granules, of the porous volume constituted by the pores with diameters less than or equal to 400 ANGSTROM . Additionally, the granules have a degree of attrition which is less than 20 %, the powder which is a DOP oil uptake of between 180 and 350 ml/100 g, and the balls a mean size of at least 80 mu m. The invention also relates to the use of the said silicas as reinforcing fillers for plastics (elastomers).

Precipitated silica particulates having controlled porosity

Abstract: Precipitated silica particulates having a BET specific surface ranging from 20 to 300 m 2 /g, a CTAB specific surface ranging from 10 to 200 m 2 /g, an oil uptake (DBP) ranging from 80 to 400 cm 3 /100 g, a pore volume ranging from 1 to 10 cm 3 /g and a mean pore diameter ranging from 10 to 50 nm, well adapted for such applications as the coating of paper and catalysis, are prepared by (a) simultaneously introducing a silicate and an acid into a dispersion of colloidal silica, thereby providing a silica suspension, (b) next decreasing the pH of such suspension to a value ranging from 3 to 7, and (c) then separating the silica particulates from the final suspension and drying them.

Thermal stability of in situ filled siloxane elastomers

Abstract: Poly(dimethylsiloxane) elastomers that had been filled with in situ precipitated silica were studied by thermogravimetric analysis, under nitrogen and in air. Both types of measurements indicated that the filler raises the temperature of thermooxidative degradation of the polymer, possibly by inactivating the terminal OH groups on the chains. Commercial fume silica was found to cause more severe degradation problems than did the in situ precipitated silica. In all cases, the degradation was more pronounced in air than in the inert atmosphere provided by nitrogen. © 1992 John Wiley & Sons, Inc.

Dispersible silica particulates

Abstract: Uniquely dispersible precipitated silica particulates, e.g., beads, powders and granulates/extrudates, very well suited for the reinforcement of elastomer/rubber matrices, e.g., tires for the automotive industry, have characteristic particle sizes, BET and CTAB specific surface areas, DOP oil absorption values, total pore volumes and pore size distributions, and reduced degree of attrition.

Polymer additive compositions

Abstract: An additive composition suitable for addition to polyolefins which comprises a synthetic silica as an antiblocking agent, a slip agent and an alkylene polyether is disclosed. The synthetic silica can be an amorphous aqueous precipitated silica or a fumed silica. The preferred alkylene polyether is polyethylene glycol and preferably has a molecular weight in the range 2,000-6,000. The alkylene polyether is preferably present in the composition in an amount from 200 to 1,500ppm. It is preferred to premix the alkylene polyether in the liquid state with the silica before adding to the composition. There is also disclosed an extrudable polymer composition comprising the additive composition and a film made from said extrudable polyolefin.

Tire sidewall composition containing silica having low pH

Abstract: The present invention relates to a pneumatic tire sidewall and to elastomeric compositions useful therefor. The elastomeric compositions are comprised of: (a) natural rubber, polybutadiene, or mixtures thereof; (b) from about 1.0 to 5.0 phr of a precipitated silica filler having a BET surface area of between 100 and 250 square meters per gram and a pH of from 4.0 to 6.5; (c) from about 1.5 to 10.0 phr of an antidegradant selected from the group consisting of amines, phenolics and mixtures thereof.

Process for refining glyceride oil using precipitated silica

Abstract: The invention relates to a process for refining glyceride oil comprising the steps of contacting the oil with amorphous silica, wherein said silica is selected from the group of precipitated amorphous silicas having a surface area of at least 400 m2 /g in pores with a diameter from at least 2 nm. Preferably said precipitated amorphous silicas have a pore volume in the range of about 1.3 to 2.5 ml/g, in pores having a pore diameter in the range of 3.6 to 1000 nm.

Polyester film comprising specific porous silica particles

Abstract: A polyester film having uniform surface and excellent running property and transparency is disclosed. Said polyester film is characterized by containing 0.01-5 wt. % of porous precipitated silica particles which are coagulates of primary particles having an average particle diameter of 0.01-0.1 μm and have a pore volume of 0.05-0.5 ml/g, a specific surface area of 30-150 m 2 /g and an average particle diameter of 0.1-0.5 μm.

Clear silicone waterbased elastomers

Abstract: Aqueous silicone emulsions which dry to a clear elastomer comprise emulsions which contain 100 parts by weight of crosslinked polydiorganosiloxane in the form of a dispersed phase with less than 10 percent of the dispersed phase particles having a particle size greater than 1000 nanometers and from 0.7 to 2.0 parts of a surfactant of the formula RSO⁸M, where R is a hydrocarbon radical of from 6 to 20 carbon atoms and M is selected from the group consisting of alkali metal cations and ammonium derivatives. A preferred method of crosslinking is by the use of an alkoxysilane and tin catalyst. The emulsion can be reinforced by addition of colloidal silica dispersions, fumed silica and precipitated silica, in which the silica particles have an average particle diameter of less than 60 nanometers, to give compositions useful as coatings and sealants.

Stable, pumpable aqueous suspensions of precipitated silica particulates

Abstract: Stable, non-gelling and pumpable aqueous suspensions of precipitated silica particulates, well adapted for the coating of paper and cardboard substrates, include an effective stabilizing amount of at least one biogum heteropolysaccharide and at least one quaternary ammonium, sulfonium or phosphonium compound (cationic surfactant).

Reinforcement from In-Situ Precipitated Silica in Polysiloxane Elastomers under Various Types of Deformation

Abstract: Elastomeric networks prepared by tetrafunctionally end linking hydroxyl-terminated poly(dimethylsiloxane) chains (PDMS) were filled by the in-situ precipitation of silica. The resulting networks were investigated under uniaxial elongation, biaxial extension, shear, and torsion in order to characterize the resulting changes in mechanical properties. Compared with the unfilled networks, the silica-filled materials showed large reinforcing effects. Specifically, their values of the modulus, ultimate strength, and rupture energy increased significantly. The results thus indicate that the PDMS networks filled by the in-situ precipitation of silica have very good mechanical properties in several, rather different deformations. Examples of other deformations of interest are equilibrium swelling, and dynamic cycling for characterization of compression set.

Foamable vinyl chloride composition

Abstract: PURPOSE:To obtain the title compsn which gives a molding having a skin layer with an excellent surface hardness and a core with a fine and uniform cell structure and is excellent in long-run properties of a mold during molding by compounding a specific vinyl chloride resin, a specific processing aid, a specific blowing agent, CaCO3, and precipitated silica each in a specified amt CONSTITUTION:The title compsn comprises 100 ptswt vinyl chloride resin having an average degee of polymn of 400-1000 (eg PVC), 2-25 ptswt polymethyl methacrylate processing aid (eg P-570, a product of Mitsubishi Rayon Co, Ltd), 01-4 ptswt thermally decomposable blowing agent (eg azodicarbonamide and NaHCO3), 1-25 ptswt CaCO3, and 01-2 ptswt precipitated silica

Effect of silica on mechanical properties and degradation of natural rubber/ethylene-vinylacetate copolymer blends

Abstract: Blends of NR and ethylene-vinylacetate copolymer (EVA), having different proportions of the components were prepared in an internal mixer and their vulcanizates evaluated for technological properties. The effect of precipitated silica on the properties and degradation of the blends was studied at different loadings

Precipitated silicic acid paste, method of manufacturing same and method of making precipitated silic acid hydrophobic by using precipitated silicic acid paste

Abstract: The paste is prepared by dispersing precipitated silica in silicone oil The precipitated silica paste is employed in the suspension phase as a hydrophobising agent in the hydrophobisation of precipitated silicas The product is spray-dried, heat-treated and ground