Mineral fibers silicate

Chemical modifications by derivitizing the surfaces of mineral fiber silicates have revealed alterations in reactivity in in vitro cell toxicity studies, suggesting a multifactorial character of particle/cell interactions [171]. In addition, the adsorption of bovine serum albumin onto asbestos fibers has been shown by infrared spectroscopy and NMR to be mediated by O—H—N hydrogen bonds [172]. In view of the various hypotheses put forward in the bulk biochemical studies and the apparent surface-oriented origins of these reactions, it is important to examine the features of the silicate/cell interfaces and surfaces. Herein we present a typical case of the interaction between a related alumino-silicate (i.e., cummingtonite) and bioorganic cell interaction. 

From every chemical group mentioned in Dana s System of Mineralogy there are minerals that form as fibers. We began with the most commonly encountered minerals, the silicate and aluminosilicate groups, and now briefly mention a few from other chemical classes. 

Synthetics and mineral fibers have other parallels. A few synthesized fibers show a higher level or secondary ordering of the crystalline structure, such as that described for chrysotile. Composed entirely of carbon, graphite fibers are synthetic fibers with such a secondary structure (see the following section). Tubular fibers of other compositions, such as aluminum silicate polymers, have also been synthesized (Farmer et al., 1977). 

Not really. Charlemagne was aware of the miraculous properties of a mineral fiber composed of various versions of magnesium silicate. In fact, the ancient Romans had discovered that this naturally occurring material was the ideal wick for the oil lamps of the vestal virgins, the watchers of the perpetual flame on the goddess Vesta s altar, because it did not burn away. We know this fiber as asbestos. 

ASBESTOS. The tenn asbestos is a generic designation referring usually to six types of naturally occurring mineral fibers which are or have been commercially exploited, These fibers are extracted from certain varieties of hydrated alkaline silicate minerals comprising two families seipe.ntin.es and amphiboles. The serpentine group contains a single fibrous variety chrysotile five fibrous forms of amphiboles are known anthophyllite, amosite, crocidolite. tremolite, and actinolite... 

Rockwool, frequently referred to as mineral fiber, is made from nonvirgin siliceous materials and is formed in a similar manner to that of fiber glass. Refractory fibers (qv), also formed in a similar manner, are available for high temperature applications. 

Asbestos constitutes several types of hydrated silicate mineral fibers. The types of asbestos, their chemical compositions, and CAS Numbers are presented in Table 3.8.1. These substances occur in nature in rocks, silicate minerals, fibrous stones, and underground mines. This class of substances exhibits unique properties of noncombustibility, high resistance to acids, and high tensile strength for which they were widely used in many products, including floor and roofing tiles, cement, textiles, ropes, wallboards, and papers. Because of the health hazards associated with excessive exposure to asbestos, the use of these substances is currently banned. 

Fibers are used in a wide variety of applications and are composed of diverse materials. Natural animal and plant fibers, including wool, silk, cotton, hemp, ramie, flax, jute, and sisal, have long been used for clothing, baskets, fishing nets, and rope. Ropemaking has been an essential skill for thousands of years, a key element in the advancement of civilizations via the oceans. The natural mineral fiber asbestos is in the silicate family. We have encountered glass fibers previously in the text (see Chapter 7). 

A survey of the literature [28, 58-65, 71, 72, 74-80] indicates that the most frequent exposure to silicon involves exposure to silica and silicates mainly in their crystalline forms. Health risks associated with the exposure to other sihcon containing compounds were reported in the mortality study of 16.661 manmade mineral fiber workers employed during 1945 to 1963 at one of 17 U.S. manufacturing plants [75]. Fiber exposure in the plants producing fibrous glass or mineral wool, or both, was associated with increased... 

Mineral fibers are manufactured from silicate melts of appropriate composition. These melts are converted into fibers with considerably more efficient use of time and space than in the manufacture of textile glass fibers, since the melts are spun at much lower melt viscosities. After solidification the fibers consist of amorphous glasses (according to X-ray diffraction measurements) with... 

Mineral fibers are manuractured from silicate melts ... 

Thermal insulators comprise an equally broad range of materials. Such inorganics as mineral fibers, magnesia, aluminum silicate, cellulose, and glass fibers are widely used for steam and hot-water pipes, furnaces, and blown-in home insulation. Organic products that are effective include plastic foams (polyurethane, polyvinyl chloride, polystyrene) and cellular rubber. There are a number of materials that may be called double insulators, since they have both electrical and thermal insulating properties,... 

Asbestos is a general term used to describe a variety of naturally occurring hydrated silicates that produce mineral fibers upon mechanical processing. Such fibrous silicate minerals were known from early times and were used in various products through the years. There are two varieties of asbestos ... 

Table 29 Properties of silicate and other mineral fibers at room temperature [18]...

Definition Natural magnesium silicate mineral fiber, of two types serpentine and amphibole common forms are chrysotile, anthophyllite, amosite, tremolite, crocidolite... 

Mineral Wool Mineral wool is a low-cost silicate fiber spun from molten slag in steel refineries. It is widely used as thermal insulation in housing and apphances. Since its composition and structure are not well controlled, it is not comparable with chopped glass fibers however, it is sometimes used as a partial replacement for them. Jim Walters Processed Mineral Fiber (PMF) in particular has been reported for such apphcations. 

Most mineral fibers are silicates and are thermodynamically stable under all but extreme conditions. They are immune to attack by biological agents. They can often withstand wide variations in temperature, pH, and other stresses without decomposing, having been exposed to a wide variety of conditions for millions of years. This resistance to degradation and change, under most atmospheric conditions, is responsible for both their usefulness and abandonment. 

Among three mineral fibers, only asbestos is a trae natural fiber. Glass and aluminum silicate fibers require human intervention in their processing, and might be better considered as man-made fibers. 

Container Insulation Tanks containing materials above atmospheric temperature may require insulation to reduce loss of heat. Almost any of the commonly used insulating materials can be employed. Calcium silicate, glass fiber, mineral wool, cellular glass, and plastic foams are among those used. Tanks exposed to weather must have jackets or protective coatings, usually asphalt, to keep water out of the insulation. 

Some commonly used insulating materials are calcium silicate, mineral slagwool, glass fiber, cellular glass, and polyurethane. 

Asbestos It is not the name of a distinct mineral species but is a commercial term applied to fibrous varieties of several silicate minerals such as amosite and crocido-lite. These extremely fine fibers are useful as fillers and/or reinforcements in plastics. Property performances include withstanding wear and high temperatures, chemical resistance, and strengths with high modulus of elasticity. When not properly handled or used, like other fibrous materials, they can be hazardous. 

Mineral Asbestos Fibers Fibrous mineral silicates... 

Siliceous fibers, silylation of, 22 703 Siliceous minerals, 22 365-366 structure of, 22 366 Siliceous zeolites, 16 818 SILIC F-Silicalite... 

SILICATE AND ALUMINOSILICATE MINERALS THAT FORM FIBERS... 

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