Silica/clay composites

The main mineral components of baghouse dust are silica, clay, some resin evaporation residue, and metal fines. Its composition is related to the way it is collected. Shake-out dust mainly contains silica and clay. Metal fines may be present in the dust collected from areas used for cleaning, grinding, and melting processes. 

Although low in volume compared with other foundry solid waste, baghouse dust may still be used beneficially in the production of portland cement. This opportunity arises from its attractive mineral composition silica, clay, and metal fines, which are needed in the cement kiln. Also, special efforts may be undertaken to characterize its chemical composition and purity. 

Table III compares the gasoline composition from three steam deactivated catalyst systems. The first contains 10% rare earth exchanged faujasite (RE FAU) in an inert silica/clay matrix at a cell size of 2.446 nm the second contains 20% of an ultra stable faujasite (Z-14 USY) at a unit cell size of 2.426 nm in inert matrix. The third contains 50% amorphous high surface area silica-alumina (70% AI2O3 30% Si02) and 50% clay the nitrogen BET surface area of this catalyst after steam deactivation is 140 m /g. All three catalysts were deactivated for 4 hrs. at 100% steam and at 816°C.

Certain oxides, particularly clays and synthetic silica-alumina composites, are very active polymerization catalysts. They probably owe their activity to the presence of acidic hydrogen. 

CAS 1332-58-7. A white-burning aluminum silicate that, due to its great purity, has a high fusion point and is the most refractory of all clays. Composition Mainly kaolinite (50% alumina, 55% silica, plus impurities and water). 

Filled polymers or composites containing silica, clay, or similar materials may have less interference from the filler in the Raman spectrum than in the IR spectrum of the polymer because most fillers are poor Raman scatterers but give strong infrared bands that interfere with polymer identification. It may not be necessary to remove the filler in order to obtain a good Raman spectrum, but such a step is usually necessary for IR. 

U.S. Pat. No. 3,546,158 [20] describes a flooring composition involving a terpolymer, a nonflbrous filler (calcium carbonate, silica, clay, kaolin, and carbon black) and a fibrous filler, such as wood flour, cellulose fibers, and asbestos. Compositions may include 25-53% by weight of nonfibrous filler and 17-40% by weight of fibrous filler, with the fillers accounting for 50-80% of the total composite weight. 

Unlike the polyurethanes and other previously discussed mortars, polyester cements are produced by a free radical chain copolymerization of a liquid unsaturated polyester and styrene. While most polyester composites are reinforced by fiber glass, polyester mortars are usually filled with silica, clay or alumina trihydrate (ATH). 

Reports of new materials and formulations and resin properties are prolific. Articles of a topical or applied interest include probes for in-situ hardness measurements on adhesives, photobase generators for image recording devices, oxygen inhibition in packaging applications, resins for sign boards, potentiometric sensors, new photodefinable polyimides, visible curable resists, " clay composites, putties, silica fillers, curable paints, soluble photocurable systems, fluorinated coatings and in-... 

The early type of catalytic cracking units involved the use of a fixed-bed operation and this type of processing has been largely supplanted by the fluid- and moving-bed types of operation. The catalysts are used in the form of powder, microspheres, spheres, and other preformed shapes. The catalysts employed are either synthetic silica-alumina composites or natural aluminosilicates. Other catalysts, such as silica-magnesia, alumina-boria, silica-zirconia, and silica-alumina-zirconia have found limited commercial application and, at present, the synthetic silica-alumina and natural clay catalysts dominate the field. 

Zhang et al. [63] prepared styrene-butadiene nanocomposites by dispersing an aqueous dispersion of montmoril-lonite and latex and flocculating the dispersion with acid. The performance of the rubber nanocomposites were compared with clay, carbon black, and silica rubber composites prepared by standard compotmding methods. The montmoriUonite loadings for the rubber nanocomposite were up to 60 phr. The morphology of the rubber nanocomposites by transmission electron microscopy appears to indicate intercalated structures. The mechanical properties of the rubber nanocomposites were superior to all of the other additives up to about 30 phr. However, rebound resistance was inferior to all of the additives except sUica. The state of cure was not evaluated. 

Eflfect of silica/clay filler loadings on (a) hardness, (b) tensile modulus, MlOO, (c) tensile strength, (d) elongation at break (%) and (e) abrasion loss of natural rubber composites. 

As a general feature, those resins with improved processability have the ability to maintain their newly acquired properties even when used as matrices in composite formulations, no matter whether the reinforcement is glass flbers/fabrics, carbon fibers, or nanoparticles (silica, clays, metals and metallic oxides, etc.). 

Toch (1916) on the other hand states that green ochre is similar in composition to gray ochre [which Toch identifies as silica, clay, and carbonaceous coloring matter ], excepting that it contains a... 

Before concluding this subsection, it must be added that the spin probe technique is also widely used in studies of polymeric composites and nano-coraposites with inorganic materials, such as silica, clay minerals or organoclays [5,6,86]. 

The physical and chemical properties, as well as exact chemical composition of heavy crude oil, vary from one source to another. Crude oils, especially the heavy crude oils, contain large quantities of asphaltenes (high-molecular-weight polar components). Other crude oil components are resins, fatty acids such as naphthenic acids, porphyrins, wax crystals, etc., which can associate to asphaltenes and affect the oil stability. Particles such as silica, clay, iron oxides, etc., can be present in crude oils. 

Fig. 8-3. Curves showing the effect of composition on the intensities of the analytical lines in the silica-alumina system. Marked absorption and enhancement effects "are showm. (Courtesy of K. K. Scott, Determination of Major Elements in Clays by X-ray. Spectroscopy, Fall, 1956 Meeting, Refractories Division, American Ceramic Society.)...

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