Silica fume filler

Fillers. Fillers mentioned for epoxy systems (subsection 2.2.6.4) are used in polyurethanes too. Ground calcium carbonate (coated as well as uncoated) is commonly used. Barium sulphate, silica fumes, wood flour and milled glass fibres are also used. 

When sand is used as a filler, the composite is referred to as a polymer mortar. Other fillers include crushed stone, gravel, limestone, chalk, condensed silica fume (silica flour, silica dust), granite, quartz, clay, expanded glass, and metallic fillers. Generally, any dry, nonabsorbent, solid material can be used as filler [4],... 

Silica fume. Silica fume (SF) is a waste product of manufacturing ferro-sihcon alloys. It consists of an extremely fine powder of amorphous silica. Average particle diameter is about 100 times smaller than that of Portland cement and the specific surface area is enormous 13000-30000 m /kg compared to 300-400 m /kg for common Portland cements. Silica fume shows an elevated pozzolanic activity and is also a very effective filler. For these reasons, addition of silica fume to Portland cement may lead to a very low porosity of the cement paste, increasing the strength and lowering the permeability. It is usually added in the proportion of 5 to 10 % and it is combined with the use of a superplasticizer in order to maintain adequate workability of the fresh concrete. 

Minor additional constituents may be fillers or one or more of the main constituents, if these have not been included as main constituents. The proportion of silica fume is limited to 10%. 

M. Frost, M. Meyerhoff, Synthesis, characterization, and controlled nitric oxide release from S-nitrosothiol-derivatized fumed silica polymer filler particles, J. Biomed. Mater. Res. A 72 (4) (2005) 409-419. 

Silica, fumed ,Strontium sulfate filler, cement... 

Silica, fumed Strontium sulfate Talc Vermiculite Whiting Wollastonite Wood flour filler, rubber articles food-contact for repeated use... 

Silica, fumed Wollastonite filler, semi reinforcing rubber Sodium magnesium aluminosilicate... 

Mora-Barrantes, I. Rodriguez, A. Ibarra, I. Gonzales, L. Valentin, J. L., Overcoming the Disadvantages of Fumed Silica as Filler in Composites. 

Boron oxide particles were incorporated to silicone rubber-based mixes containing fumed silica (reinforcing filler) and reference mineral fillers - aluminum hydroxide, wollastonite, calcined kaolin, mica (phlogipite) and surface modified montmorillonite with dimethyl-dihydrogenatedtal-low quaternary ammonium salt. Acidic character of boron oxide, which can disturb the peroxide curing process, was compensated by addition of magnesium oxide. The influence of boron oxide particles on properties of composites was determined and mechanism of their ceramization process studied. 

The brittleness of cement-based composites increases with their compressive strength. It may be observed that in recent years the strength of conventional concrete has increased, thanks to improved technology and material composition. Also the extended use of micro-fillers like silica fume is the main reason that strength has increased considerably. However, the increase of E and Gf is quite moderate, and consequently tends to lower values. In the design of high performance concretes their brittleness is of special concern (cf. Section 13.4.5). 

Fly ash (FA), silica fume (SF), metakaolin and other micro-fillers are furnished as slurry or powders. SiHca fume is considered as the most efficient micro-filler for HPC. Its role is based on ... 

When micro-fillers like silica fume (SF) or fly ash (FA) are used for high performance concrete, the method of adding them to the mix should be elaborated and carefully executed the same concerns other components. The good dispersion of SF is particularly important because its effects result from combined physical and chemical mechanisms. 

Additives used in final products Fillers carbon nanotubes, fumed silica, graphite. Fillers molybdenum disulfide, montmorlllonite, nanosilica, titanium dioxide, vanadium oxide Plasticizers dioctyl phthalate, ethylene carbonate, polyoxyethylene-sorbitane monolaureate, propylene carbonate, polyethylene and polypropylene glycols, tetraethylene glycol, tetraglyme Antislatics polyoxyethylene sorbitan monolaurate, polyoxyethylene glycol, polyoxyethylene octylphenyl ether ... 

Added filler will increase the viscosity and resistance to flow of a polymer. This is essential in adhesives, which would drain out of the joint by gravity or be sucked out of the glue line by capillary attraction. Viscosity increase becomes larger as the particle size is reduced. Fumed (aerosol) silica, a filler that introduces a structure to the liquid, can produce a thixotropic mixture (Anon, n.d. Byrne, 1984). Ease of handling of a liquid adhesive can be improved by additions to the polymer of 3-10% of its own weight in silica. The thickening effect is greatest in non-polar solvents when the powder is well dispersed. 

Figure 1 Modulus of RHA composites as a function of filler loading. NS, FUMED and PP/talc represents Neuberg Silica, fumed silica and talc-filled polypropylene...

For viscosity or sag control. When the rubber base adhesive is applied on a vertical surface, addition of a filler prevents the adhesive from running down the wall. In solvent-borne formulations, fumed silica can be used as anti-sag filler. In water-borne systems, clays impart yield stress and excellent sag control. 

Although natural quartz, cristobalite and opal are used as fillers, only synthetic products (fumed and precipitated silicas) find use as fillers in rubber base adhesives. 

Fumed silicas (Si02). Fumed silicas are common fillers in polychloroprene [40], natural rubber and styrene-butadiene rubber base adhesives. Fumed silicas are widely used as filler in several polymeric systems to which it confers thixotropy, sag resistance, particle suspension, reinforcement, gloss reduction and flow enhancement. Fumed silica is obtained by gas reaction between metallic silicon and dry HCl to rend silica tetrachloride (SiCU). SiC is mixed with hydrogen and air in a burner (1800°C) where fumed silica is formed ... 

Reinforcing fillers (active) Fumed Silica (Si02) precipitated calcium carbonate (CaCOi) carbon black Thixotropic reinforcing agents (non-slump), adjustment of mechanical properties (cohesion) provide toughness to the elastomer as opposed to brittle materials. 

Various additives and fillers may be employed. Calcium carbonate, talc, carbon black, titanium dioxide, and wollastonite are commonly used as fillers. Plasticizers are often utilized also. Plasticizers may reduce viscosity and may help adhesion to certain substrates. Thixotropes such as fumed silica, structured clays, precipitated silica, PVC powder, etc. can be added. Adhesion promoters, such as silane coupling agents, may also be used in the formulation [69]. 

Fumed silica, 22 33, 367-368, 374t, 383, 400, 581. See also Pyrogenic silica in synthetic fillers, 11 315-316 Fumed xerogel, powder used in cosmetics, 7 84 It... 

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