Mineral fibers number

Environmental tobacco smoke (ETS) is the diluted mixture of pollutants caused by smoking of tobacco and emitted into the indoor air by a smoker. Constituents of ETS include submicron-size particles composed of a large number of chemicals, plus a large number of gaseous pollutants. Fibers in indoor air include those of asbestos, and man-made mineral fibers such as fiberglass, and glass wool. 

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. 

Palekar LD, Most BM, Cofiin DL. 1988. Significance of mass and number of fibers in the correlation of V79 cytotoxicity with tumorigenic potential of mineral fibers. Environ Res 46 142-152. 

Tobacco smoke. Tobacco smoke produces particulate matter that acts as an adsorption site for toxic vapors)26 In addition to particulates, tobacco smoke produces more than 4000 individual toxic compounds, including 43 known carcinogens. 27 Many of the toxic effects of tobacco smoke that have been established empirically cannot be ascribed to individual compounds in that smoke. With more than 4000 different toxins, the number of mixtures possible is incalculable. Numerous examples of synergism between tobacco smoke and other toxicants have been identified. These include tobacco smoke and asbestos or other mineral fibers, I28 29 alcohol, I30 31 organic solvents, 32 biological... 

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,... 

This is the Chemical Abstracts Service registry number. The CAS number is a unique number assigned to each substance by the Chemical Abstracts Service of the American Chemical Society. It definitively identifies the substance regardless of how it is named or how its formula is written. No two substances have the samw CAS. HAPs such as Nickel Compounds and Fine Mineral Fibers that are groups of substances do not have a specific CAS. An example of a chemical CAS is Fluorene CAS 86-73-7. 

Natural fibers are classified based on their origins, whether they are plant, animal or mineral fibers. All plant fibers are composed of cellulose while animal fibers consist of proteins (hair, silk, and wool). Plant fibers include bast (or stem or soft scleren-chyma) fibers, leaf or hard fibers, seed, fruit, wood, cereal straw, and other grass fibers [1]. Over the last few years, a number of researchers have been involved in investigating the exploitation of natural fibers as load bearing constituents in composite materials. The use of such materials in composites has increased due to their relative cheapness, their ability to be recycled, and because they can compete well in terms of strength per weight of material [2]. Provided below is the classification of natural fibers based on origin ... 

Few persons on Earth should have more reason to damn mineral fibers and their industry than I. Hopefully, this presentation will treat both sides of this question, with objectivity and fairness. After dealing almost daily with an ever increasing number of rules, regulations, and roadblocks that stand in my way to deliver new substances that I believe could be a service to everyone, I am frustrated on a number of issues. I find that I first vent my frustrations by writing them to get them out of the way, and then I delete them to spare you my concerns. My apologies, in the event I do an inadequate job of removing my disdain at times. 

Fiber Analysis. Paper may be composed of one or several types of fibers, eg, animal, vegetable, mineral, and synthetic (see Eibers). Paper is generally composed of woody vegetable fibers obtained from coniferous (softwood) and deciduous (hardwood) trees. QuaUtative and quantitative methods have been developed to determine the fibrous constituents in a sheet of paper (see TAPPI T401). However, the proliferation in the number and types of pulping processes used have made the analysis of paper a much more complex problem. Comprehensive reviews of the methods are given in References 20 and 23. 

Instrumental Methods for Bulk Samples. With bulk fiber samples, or samples of materials containing significant amounts of asbestos fibers, a number of other instmmental analytical methods can be used for the identification of asbestos fibers. In principle, any instmmental method that enables the elemental characterization of minerals can be used to identify a particular type of asbestos fiber. Among such methods, x-ray fluorescence (xrf) and x-ray photo-electron spectroscopy (xps) offer convenient identification methods, usually from the ratio of the various metal cations to the siUcon content. The x-ray diffraction technique (xrd) also offers a powerfiil means of identifying the various types of asbestos fibers, as well as the nature of other minerals associated with the fibers (9). 

Substitution and variations in the tetrahedral sites change the manner of side linkages for the ribbons, effecting the octahedral cation and water associations. In addition, different ribbon widths can lead to different numbers of octahedral cations. Variation in the width of chains and substitution of cations and water are easily accomplished, which means that accurate and consistent chemical and crystal structural data on these minerals are difficult or, at best, approximate. However, the minerals do form fibers with a consistent fiber axis repeat of about 0.512 nm (Preisinger, 1959 Rautureau et al., 1972). Sepiolite and palygorskite represent the widest possible structural and chemical diversity among fibrous silicate minerals. 

The discrepancy in numbers between natural and synthetic varieties is an expression of the usefulness of zeolitic materials in industry, a reflection of their unique physicochemical properties. The crystal chemistry of these aluminosilicates provides selective absorbtion and exchange of a remarkably wide range of molecules. Some zeolites have been called molecular sieves. This property is exploited in the purification and separation of various chemicals, such as in obtaining gasoline from crude petroleum, pollution control, or radioactive waste disposal (Mumpton, 1978). The synthesis of zeolites with a particular crystal structure, and thus specific absorbtion characteristics, has become very competitive (Fox, 1985). Small, often barely detectable, changes in composition and structure are now covered by patents. A brief review of the crystal chemistry of this mineral group illustrates their potential and introduces those that occur as fibers. 

We have recorded 388 minerals (Appendix 1) that occur, at least occasionally, as fibers some minerals are found only in fibrous form. This number includes more than 92 silicate and aluminosilicate species, most of them common rock-forming minerals. This list, only a fraction of the 3000 minerals known, probably represents only a sampling of naturally occurring fibers. 

Although there are a number of contradictory reports regarding the effects of talc, the contradiction has been ascribed to the differences in mineral composition of the various talcs, which include pure talc, talc associated with silica and other nonasbestiform minerals, and talc containing asbestiform fibers such as tremolite and anthophyllite. ... 

Amongst the important chemical conversions of macromolecular substances are the various reactions of cellulose. The three hydroxy groups per CRU can be partially or completely esterified or etherified. The number of hydroxy groups acetylated per CRU are indicated by the names, i.e., cellulose triacetate, cellulose 2-acetate, etc. Another commercially important reaction of cellulose is its conversion to dithiocarboxylic acid derivatives (xanthates). Aqueous solutions of the sodium salt are known as viscose they are spun into baths containing mineral acid, thereby regenerating the cellulose in the form of an insoluble fiber known as viscose rayon. 

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