Fibrous materials specific fibers

The term fiber basically refers to filamentary material and is often used synonymously with filament, monofilament, whisker, and yarn. A filament is the smallest unit of a fibrous material and is usually not used alone. It can be identified as any material in a form such that it has a minimum length of at least 100 times its diameter. Diameters are usually 0.004-0.005 in. (0.10-0.13 mm). They can be continuous or reduced to short lengths (discontinuous). The industry lists fibers as having a specific length, such as 0.125 in. (3.2 mm). 

Preservative film materials intended for packing large-size metal ware with sharp edges should of course show elevated resistance to rupture and puncture. With this aim, polymer films are reinforced by glass fibers and kapron by alternating air impermeable and inhibited polymer layers with non-woven fabric [37,38[. Fibrous materials with developed specific surface and porosity can serve as a container for the evaporating Cl [39[. 

Based upon their mechanical and processing properties, many natural and renewable polymers are quite suitable to replace petroleum- based plastics in specific applications where an extended life span of plastic product is not desirable. Furthermore, consumers acceptance of such bio-based plastics is expected even if natural polymer price represents a limitation on the cost of the final products. Materials such as commodity crops, agricultural waste and/or by-products are a good source of natural and renewable polymers and are comparatively less expensive. Agro-fibers, which represents a considerable portion of such natural materials is available on a worldwide basis and are being used in a variety of tq>plications. In some applications, fibrous materials have been blended with thermoplastic mauix to develop composites containing various percentages of the fibers ... 

Nanofibers are generally produced from polymers which deviate from the conventional fiber-forming type of materials, and so it may be apprehended that the scope of use of these nanofibers may be far beyond the use of standard fibers, microfibers or fibrous materials. The bottom-up method modifies the fibers at a molecular or supramolecular level of fragmentation and transforms them into a polymer/polymer blend before the formation of fibers, which gives them new, specific properties favorable from a practical point of view. Nanocellulose fibers possess optimized product properties and target-directed development, quantification of eco-efficiency and sustainability factors. 

Grain n. The direction, size, arrangement, appearance or quality of the fibers in fibrous material such as paper, wood or veneer. To have a specific meaning the term must be qualified. Also, the direction of molecular orientation in a non-fibrous material. 

To date, there are many medical devices that include fibrous material. Beyond the specifics relating to materials, this diversity is attributable on one hand to the variety of pathologies that these devices aim to solve and on the other hand to the multitude of industrial textile processes. Indeed, fibers could be used as units or in cohesive structure forms thanks to textile processes, with the ability to tune and control the obtained structure features in more or less anisotropic stmcture, or even in unidirectional, bidirectional, or tridimensional architectures. 

Table 17.1. Specific heats of fibers and non-fibrous materials. Fibers were dried and tested at room temperature.

Where soil adsorption predominantly a result of dispersion and van der Waals interactions, nonpolar materials such as carbons and hydrocarbon oils can be especially difficult to remove from hydrophobic surfaces such as polyesters. More hydrophilic soils such as clays, fatty acids, and other material, on the other hand, can be more difficult to remove from hydrophilic surfaces such as cotton. Mechanical forces can also inhibit cleaning action, especially in fibrous materials with particulate soils, as a result of entrapment of the particles in the fibers. It is obvious, then, that the cleaning process can be extremely complex, and optimum results may be possible only for specifically defined systems. Like the universal solvent, the universal detergent is, in all likelihood, beyond our technological reach. 

Carbon Composites. Cermet friction materials tend to be heavy, thus making the brake system less energy-efficient. Compared with cermets, carbon (or graphite) is a thermally stable material of low density and reasonably high specific heat. A combination of these properties makes carbon attractive as a brake material and several companies are manufacturing carbon fiber—reinforced carbon-matrix composites, which ate used primarily for aircraft brakes and race cats (16). Carbon composites usually consist of three types of carbon carbon in the fibrous form (see Carbon fibers), carbon resulting from the controlled pyrolysis of the resin (usually phenoHc-based), and carbon from chemical vapor deposition (CVD) filling the pores (16). 

Proteins are usually separated into two distinct functional classes passive structural materials, which are built up from long fibers, and active components of cellular machinery in which the protein chains are arranged in small compact domains, as we have discussed in earlier chapters. In spite of their differences in structure and function, both these classes of proteins contain a helices and/or p sheets separated by regions of irregular structure. In most cases the fibrous proteins contain specific repetitive amino acid sequences that are necessary for their specific three-dimensional structure. 

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