Paper structure fibers

In Activity 3.4, paper is made in a basic solution. For paper in which wood fibers are used, NaOH (sodium hydroxide) can make the pulp mixture basic by providing an excess of OH" ions. The NaOH breaks down cellulose fibers in the wood and other plant materials that form the primary paper structure. A suspension of these fibers can be placed on fabric on an embroidery hoop. Also, CIO- ions can act as oxidizing agents in the basic solution. Finally, KA1(S04)2 12H20 (potassium aluminum sulfate Alum) is added to the cellulose fibers to coagulate the pulp (clay is added when it is not naturally present). The aluminum ion (Al3+) helps the clay loosely bond to the cellulose fibers so that the resulting paper is dense and smooth. 

The folding endurance is primarily a measure of the response of fiber-fiber bonds and, to a lesser extent, that of the fibers to alternate compression and tension during the folding. The strength, flexibility, and other physical characteristics of these bonds are profoundly affected by any of the factors associated with aging. As noted above, this may be attributed to the more poorly organized structure and lower crystallinity and, consequently, greater accessibility of the bonds in the paper structure. 

Polysaccharides are grown by linkage of simple sugar units (carbohydrates). One example is starch, which is readily metabolized by humans and animals. Another is cellulose, which forms the structural fibers of plants and trees and appears in linen and cotton fabrics and in paper. 

Lindstrom H, Harris P, Sorensson CT and Evans R (2004) Stiffness and wood variation in 3-year old Pinus radiata clones. Wood Science and Technology, 38 579-97 Lindstrom T (1986) The concept and measurement of fiber swelling. In Bristow AJ and Kolsseth P (eds), Paper structure and properties. Marcel Dekker, New York, 75-97 Littleford TW (1978) Flexural properties of dimension lumber from western Canada. VP-X-179. Environment Canada, Forestry Directorate and Western Forest Products Laboratory, Vancouver, BC... 

Celluloses can be converted to other useful products by reorientation of their fiber structure. Paper, parchment paper, vulcan fiber, mercerized cotton, and hydrocelluloses belong in this class. 

A recent study [15] presented a novel method to create superamphipho-bic paper by modifying the paper fiber size and structure with plasma etching and fluoropolymer deposition (see Figure 10.7). The heterogeneous nature of the paper structure is drastically different from that of artificially created superamphiphobic surfaces. By refining the wood fibers, smaller diameter fibers (fibrils) were created so that liquid droplets did not get... 

Hydrogen bonds are water sensitive. Thus, the addition of water to a dry paper structure results in a serious, rapid weakening of fiber-to-fiber hydrogen bonds and a simultaneous decrease in paper strength and integrity. 

The premise that discontinuous short fibers such as floating catalyst VGCF can provide structural reinforcements can be supported by theoretical models developed for the structural properties of paper Cox [36]. This work was recently extended by Baxter to include general fiber architecture [37]. This work predicts that modulus of a composite, E can be determined from the fiber and matrix moduli, Ef and E, respectively, and the fiber volume fraction, Vf, by a variation of the rule of mixtures,... 

Of all possible manufacturing proceses for macroporous separators to be employed in alkaline batteries, the wet-fleece process using paper machines is the predominant one [130] it permits a very uniform ( cloud-free ) production of such material and the use of different types of fibers as well as of short and very thin fibers, thus achieving a uniform structure of small pores (Table 15). 

Apart from manifold structures, carbons can have various shapes, forms, and textures, including powders with different particle size distributions, foams, whiskers, foils, felts, papers, fibers [76, 77], spherical particles [76] such as mesocarbon microbeads (MCMB s) [78], etc. Comprehensive overviews are given, for example in [67, 71, 72], Further information on the synthesis and structures of carbonaceous materials can be found in [67, 70, 72, 75, 79]. Details of the surface composition and surface chemistry of carbons are reviewed in Chapter II, Sec. 8, and in Chapter III, Sec. 6, of this handbook. Some aspects of surface chemistry of lithiated carbons will also be discussed in Sec. 5.2.2.3. 

Recently, many papers have been published on fiber catalysts and foam structures (Figure 9.2). Although, strictly speaking, fibers and foams might not be considered as structured systems, beds of such catalysts exhibit typical features of structured catalysts, namely, low pressure drop, uniform fiow, a good and uniform access to the catalytic surface, and they are definitely nonrandom. Therefore, we have included them in this chapter. 

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