Fine Structure of Cellulose

The realization that the shape and frequency of the infrared absorption band associated with the fundamental hydroxyl stretching-vibrations in cellulose give considerable information about the hydrogen-bonding conditions in cellulose - led to the development of refined methods for studying the detailed structure of cellulose. 

Early deuteration studies - were limited by the fact that the rate and extent of the exchange between deuterium oxide and the hydroxyl groups in cellulose had to be determined by density measurements, whereas an 

Attempts to determine the absolute crystallinities of celluloses by x-ray diffraction methods are complicated by the fact that the scattering curves 

Comparison of Crystallinity Values Obtained by Infrared and by X-ray Measurements 

Although the bands in the 3000-cm. region could be assigned to the stretching of the 0—H and C—H groups, the results were limited by interference by the absorption bands of the amorphous material. This circumstance was avoided by converting all of the hydroxyl groups in the 

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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... 

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 ... 

Because of the lack of homogeneous, purified, cellulose-degrading enzymes, having a variety of action patterns, that will act on the native, unmodified polysaccharide, it has not yet been possible to investigate the fine structure of cellulose in a manner analogous to that used for amylose. The situation is complicated by the insolubility of the substrate and its resistance to degradation by any single enzyme. A system of enzymes, the function of at least one component of which is at present unclear, is required. For this reason, it has not yet been possible to examine the fine structure of cellulose enzymically. 

J. R. Colvin, Tip-growth of bacterial cellulose microfibrils and its relation to tire crystallographic fine structure of cellulose, J. Polym. Sci. B, 4 (1966) 747-754. 

Early work on the fine structure of cellulose has been reviewed extensively by Sisson [255] and by Hermans [256]. The observations of Herzog and Jancke [257] who, in 1920, recognized that natural cellulosic material gave identical x-ray diagrams and led to the conclusion that these materials should have identical crystalline structure. The unit cell structure proposed by Meyer and coworkers [258-260] is still used to describe cellulose. The structure of the unit cell for cellulose is shown in Figure 10.82. 

Fine Structure of Cellulose Acetate and Triacetate Fibers.795... 

The effect of epichlorohydrin- or formaldehyde-crosslinking on the fine structure of cellulose has been investigated. Crosslinking was shown to increase the number of accessible hydroxy-groups, thus improving cellulose reactivity in some esterification reactions. 

Cellulose is one of the most important natural materials that occurs in wood, cotton, hemp, flax and other plant-based materials. It can be even synthesized by algae, tunicates, and some bacteria. Currently, much attention is paid to the studies of the fine structure of cellulose, which depends on the origin of the plant from which cellulose was obtained. Furthermore, this essentially inexhaustible material is more and more often regarded as very promising composite filler providing unique properties along with biodegradability. 

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