Materials general categories

Classification of On the basis of chemistry and atomic structme, materials are classified into three Materials general categories metals (metallic elements), ceramics (compounds between metallic and nonmetallic elements), and polymers (compoimds composed of carbon, hydrogen, and other nonmetallic elements). In addition, composites are composed of at least two different material types. 

The overall extraction process is sometimes subdivided into two general categories according to the main mechanisms responsible for the dissolution stage (/) those operations that occur because of the solubiHty of the solute in or its miscibility with the solvent, eg, oilseed extraction, and (2) extractions where the solvent must react with a constituent of the soHd material in order to produce a compound soluble in the solvent, eg, the extraction of metals from metalliferous ores. In the former case the rate of extraction is most likely to be controUed by diffusion phenomena, but in the latter the kinetics of the reaction producing the solute may play a dominant role. 

Early marketing efforts for spunbonded fabrics centered on their substitution for existing, ie, woven, textile fabrics. Generally, success was achieved ia areas where only fiinctionahty was important. Extremely slow progress has occurred ia areas where textile-like aesthetics are required. Nevertheless, spunbonded fabrics are recognized as a unique class of materials within the general category of nonwoven fabrics (see Nonwoven fabrics, staple fibers). 

A wealth of important materials fall under the general category of synthetic polymers. All share a common theme of being made up of sequences of one or more monomer units. 

Paper is one of the oldest and most commonly used packaging materials. Generally it is used to keep a product clean and for mechanical strength when combined with other materials. It does not protect a product from atmospheric change, but only from mechanical contaminants such as dirt. Coated papers are much more functional. Waxed papers fall into this category and provide much better protection from moisture and, in some cases, from gas (oxygen) transmission. 

Polypropylene film is found in a variety of applications. Films are thin plastic sheets with thicknesses less than 250 pm. Applications for these films include candy mappers, plastic label material, electrical capacitors (which requires very pure polymer), and fiber glass insulation backing. There are two general categories of polypropylene films unoriented and oriented. Films are manufactured through either a cast or a blown film extrusion process. Oriented films exhibit improved strength relative to unoriented films. This means that they can be... 

Class I, II and III are also used by NFPA to define the range of certain materials in categories based mainly on flash points. Class II and III materials generally do not provide sufficient vapors to require specification of an electrically classified area, so areas are only defined by Class I flammable materials. 

Five general categories of what can go wrong with self-reactive materials are ... 

Printed material generally includes books, newspapers, magazines, pamphlets, or excerpts of essays—in other words, any written material on your topic. These printed materials are usually grouped into two categories ... 

Of the three general categories of transport processes, heat transport gets the most attention for several reasons. First, unlike momentum transfer, it occurs in both the liquid and solid states of a material. Second, it is important not only in the processing and production of materials, but in their application and use. Ultimately, the thermal properties of a material may be the most influential design parameters in selecting a material for a specific application. In the description of heat transport properties, let us limit ourselves to conduction as the primary means of transfer, while recognizing that for some processes, convection or radiation may play a more important role. Finally, we will limit the discussion here to theoretical and empirical correlations and trends in heat transport properties. Tabulated values of thermal conductivities for a variety of materials can be found in Appendix 5. 

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