Sheet silicates structural characteristics

The new large-aperture MCM-41 family of zeolites mentioned earlier have FD s far below those expected from this analysis. This is due to the novel structural type of these frameworks. They consist of a silica bilayer wrapped onto hyperbolic surfaces (or cylinders), rather than the hyperbolic silica monolayers characteristic of conventional zeolites. The structures of MCM-41 zeolites are closer to those of the double-layer sheet silicates [20] than zeolites. In these cases, the connectivity within each layer is three (the fourth link fuses the two layers), and pores of infinite radius are apparently realisable, e.g. CaAl2Si208, which is a flat bilayer ... 

The nanocomposite presented here is a composite material reinforced with silicate sheets. Silicate sheet is an ultrafme filler of nanometer size, which is almost equal to the size of the matrix polymer. Although the content of the filler is as little as several wt.%, individual filler particles exist at a distance as close as tens of nanometers from each other because of their ultrafme size. One end of the polymer is strongly restrained to the silicate sheet by polar interaction. Thus, the nanocomposite has a microstructure that has never been seen in conventional composites. The characteristic properties of the nanocomposite are derived from this very structure. Considering the properties, the nanocomposite may be, in a sense, an embodiment of the ideal polymer composite, or a completely novel composite. Silicate sheet can be regarded as a rigid inorganic polymer. In this sense, the nanocomposite realized is a molecular composite in which a silicate sheet is used instead of an organic rod-like polymer. 

CAS 12001-26-2. Any of several silicates of varying chemical composition but with similar physical properties and crystalline structure. All characteristically cleave into thin sheets that are flexible and elastic. Synthetic mica is available. It has electrical and mechanical properties superior to those of natural mica it is also water-free. 

Silicones have properties of both plastics and minerals. The organic groups give the chains flexibility and produce the weak intermolecular forces between chains that are characteristic of a plastic, while the O—Si O backbone confers the thermal stability and nonflammability of a mineral. Structures similar to those of the silicates can be created by adding various reactants to form silicone chains, sheets, and frameworks. Chains are oily liquids used as lubricants and as components of car polish and makeup. Sheets are components of gaskets, space suits, and contact lenses. Frameworks find uses as laminates on circuit boards, in nonstick cookware, and in artificial skin and bone. 

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