Fibers random arrangement

Fibrous Composites. These composites consist of fibers in a matrix. The fibers may be short or discontinuous and randomly arranged continuous filaments arranged parallel to each other in the form of woven rovings (coUections of bundles of continuous filaments) or braided (8). In the case of chopped strand mat the random arrangement is planar. In whisker (needle-shaped crystals or filaments of carbon and ceramics) reinforced materials the arrangement is usually three-dimensional and the resulting composites are macroscopically homogeneous. 

As another extracellular component in the cornea, the Bowman s layer is an acellular and amorphous band between the corneal epithelium and stroma. The layer is about 8-12 [im thick and consists of randomly arranged collagen fibers (types I and III) and proteoglycans. The physiological function of Bowman s layer is not yet completely understood, since not all animal species exhibit this membrane in the corneal structures, but an important role in the maintenance of the corneal epithelial structure is expected or probable, since a damaged Bowman s membrane usually results in scarring during wound repair [16],... 

The transverse modulus (Mt) and many other properties of a long fiber resin composite may be estimated from the law of mixtures. The longitudinal modulus (Ml) may be estimated from the Kelly-Tyson equation (8.5), where the longitudinal modulus is proportional to the sum of the fiber modulus (Mp) and the resin matrix modulus (Mm)- Each modulus is based on a fractional volume (c). The constant k is equal to 1 for parallel continuous filaments and decreases for more randomly arranged shorter filaments. 

The relationship of the thermal conductivities of fabrics and volume fractions of water in the interfiber spaces was expressed by a quadratic curve when the heat flow was normal to the fabric surface and by a straight line when the flow was parallel to the warp yarns. Except for hairy wool fabrics, the thermal conductivity of various wet fabrics may be calculated from the equations of Naka and Kamata (J3). An earlier investigation used an environmentally controlled room as a periodic heat source, and observed conductivities of 1-2 x 10 l cal/cm-sec °C for cotton, linen, and wool fabrics, and changes to 2-10 x 10 when the water content of these fabrics were increased ( ). After correcting for anisotropic effects, good agreement between actual conductivity measurements of wool fabrics and those calculated from a mathematical model of a random arrangement of fibers was observed. 

Spinach is also an excellent source of manganese. However, spinach contains high amounts of soluble fiber and oxalic acid. Both of these factors have been found to inhibit the utilization of iron. Using two 5-day periods in a cross-over design, manganese utilization from spinach was determined. Subjects (12) consumed their normal, self-selected, self-recorded diets. During one of the two randomly arranged periods, subjects were asked to eat one 8 oz. can of spinach. 

Six subjects who were participants in a study on effects of several purified fibers on nutrient utilization and who were vegetarians were age, sex, height, weight and ethnic-group matched with six subjects from this series of studies who were omnivores. The laboratory-controlled diet fed to all subjects for 21-28 days was a lacto-vegetarlan type. The basal diet provided 10.10 mg of zinc and 14.7 g of fiber. Cellulose, hemi-cellulose or pectin were added to the basal diet to provide 20 g fiber/day in separate, randomly arranged period of 6 to 7 days each. 

Bowman s layer is a thin homogeneous sheet of acellular randomly arranged collagen fibers lying between the epithelial basement membrane and the stroma. Bowman s layer is relatively tough and provides substantial resistance to corneal injury or infection. Because it cannot regenerate, scarring results when it is disrupted. 

Figure 17, TEM of randomly arranged microfibrils in the fiber primary wall (PW) of balsam fir direct carbon replica.

Because the fiber diameters are usually not all equal and the fibers are arranged in a more or less random fashion, i)n should be inteipreted a,s an effective fiber efficiency that cun be calculated from (3.44) and ba.sedon an average diameter, r7, usually the arithmetic average. In an experimental deiermination of t/fj. the practice is to measure N and /V2, the inlet and outlet concentration of a nionodispcrse aerosol passed through the filter. The average fiber diameter, d, can be determined by microscopic examination. 

Description of polypropylene in the literature is often accompanied by terms atactic, isotactic, or syndiotactic. The origin of the terms is as follows. Side methyl groups in polypropylene chains can be all on the same side of plane (as it is shown above in a very simplified manner, as in reality carbon atoms in the chain are in zig-zag stereoconfiguration), on alternate sides, or in a random arrangement with respect to plane of carbon atom chain. These forms of PP are called isotactic (fiber-forming), syndiotactic, and atactic, respectively. All these forms are related to homopolymers of polypropylene. PP used for common applications, including WPC, is atactic and will be referred to here as polypropylene. 

A fiber will remain in the oriented state at room temperature indefinitely however, if heated to an elevated temperature in the absence of an external stress, the fiber will revert to the essentially random arrangement of the unoriented crystalline polymer. The crystallites themselves are destroyed by melting. 

The pre-mixed molding materials contain randomly arranged fibers. They give properties approximately equal in all directions though with... 

Non-woven mat A mat of glass fibers in random arrangement, hghtiy bonded so as to be able to be handled and cut, used in making reinforced-plastics structures. 

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