Cellulose fine structure

Millett, M. A. Goedken, V. L. Modification of Cellulose Fine Structures—... 

That such features of cellulose as the crystal lattice form are significant determinants of cellulase action has only recently been established (19), although a great deal remains to be learned about the enzymatic importance of cellulose fine structure. It is clearly established, however, that each of the three water-stable crystal forms of cellulose is distinct in the rate at which it is hydrolyzed and in its properties as an inducer of cellulase. For example the Trichoderma viride cellulase from culture extracts exhibits a lower activation energy in attacking the crystal lattice form used in culture growth, than in attacking the other lattice forms (Table I). 

Ranby, B. G. Fine Structure and Reactions of Native Cellulose. Diss. 

An important chemical finishing process for cotton fabrics is that of mercerization, which improves strength, luster, and dye receptivity. Mercerization involves brief exposure of the fabric under tension to concentrated (20—25 wt %) NaOH solution (14). In this treatment, the cotton fibers become more circular in cross-section and smoother in surface appearance, which increases their luster. At the molecular level, mercerization causes a decrease in the degree of crystallinity and a transformation of the cellulose crystal form. These fine structural changes increase the moisture and dye absorption properties of the fiber. Biopolishing is a relatively new treatment of cotton fabrics, involving cellulase enzymes, to produce special surface effects (15). 

Shirakashi, K., K. Ishikawa, and K. Miyasaka The fine structure of cellulose on cellulose-polymethyl methacrylate copolymerization. Part I. J. Soc. Text, and Cell. Ind. (Japan) 19, 178 (1963) Part II. Ibid 19,182 (1963). 

Considering the fine structure of cellulose, it is known that the majority, if not all, of the glucose units are linked by glycosidic combination into chains carbon atom 1 of one unit being linked to carbon atom 4 of the adjacent unit. Meyer s surmise37 that the copper enters into a complex with the hydroxyl groups on carbon atoms 2 and 3 of a single... 

RSnby, B. (1952). Fine structure and reactions of native cellulose. Ph.D. Thesis, Univ. of Uppsala, Uppsala. 

V. Fine Structure of Wood Cellulose and Associated Polysaccharides. 328... 

Muhlethaler K (1969) Fine structure of natural polysaccharide systems. In Marchessault RH (ed), Proceedings of 6th cellulose conference. Wiley, New York, 57-67 Murphy RJ, Barnes HM and Dickinson DJ (2002) Vapor boron technology. In Enhancing the durability of lumber and engineered wood products. Forest Prodncts Society, Madison, Wisconsin, 251-6... 

Gas adsorption is a suitable method for a fractal analysis because it is sensitive to the fine structure of the pores and has negligible adverse affects on the pore system. The results are usually analyzed by using fractal generalizations of the Brunauer-Emmett-Teller (BET) isotherm (30) or of the Frenkel-nalsey-TfiU (FHH) isotherm (31). The latter may also be seen as a fractal generalization of the Kelvin equation and is therefore also applicable in the capillary condensation regime (32). It has been claimed that the fractal BET theory is more appropriate for mass fractals (see sect. Fractals ), whereas surface fractals are to be analyzed using the fractal FHH theory (33). These methods have been applied to cellulose powders (34) and tablets (35). 

The differences between regular and high-tenacity rayon are to be found in the degree of degradation of the cellulose which has occurred during preparation of the viscose, the degree of crystallization, the size of the crystallites, the degree of orientation and the fine structure and uniformity of the filament. 

B. G. Ranby, Inst. Phys. Chem., Univ. Uppsala, Arkiv Kemi, 4, 241 (1952). Fine structure and reactions of native cellulose. Electron microscope study of morphology of celluloses from wood, cotton, bacteria, tunicates, and algae behavior of samples on swelling in sodium hydroxide and hydrolytic degradation. 

It is found as a component of fungal and bacterial cell-walls, in insect cuticles, and as the shell of crustaceans. Being so similar to cellulose in chemical composition, its structure is important, if for no other reason than that comparison of the two structures might aid in our understanding of each. The similar fibrillar fine-structure (see Fig. 12) of these two polysaccharides is noteworthy, as the lateral forces between molecules are different. Although chitin does not occur in Nature specifically as a fiber, it is frequently found well-oriented in bristles and as tendon material. Samples from invertebrates are usually admixed with protein and carbonate, both of which must be removed before x-ray diagrams of high quality can be obtained. 

The study of fine structure in cellulose by infrared spectroscopy rests largely on the ease with which this technique can characterize the hydrogenbonding system of the hydroxyl groups. There are other changes in the spectrum caused by fine-structure changes (see, for example, Section III.2), but some of these are more difficult to interpret and are used in an empirical manner only. 

A complete definition of the fine structure of cellulose would entail a knowledge of the exact distribution of the size and shape of these ordered and disordered regions, a position which has not yet been achieved. However, a report claims that four types of material which differ in the degree of orderly arrangement of molecular chains can be distinguished in both native and regenerated celluloses, although quantitative measurements have only been made on one viscose-rayon fiber. These four types of material are ... 

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