Cellulose, alkali bacterial

Fig. 9-3. Transition of cellulose I (/r = 0) to cellulose II (/r = 1) during cold alkali treatment of wood cellulose (W), cotton cellulose (C), bacterial cellulose (B), and animal cellulose (A) (RSnby, 1952).

Colvin155 was the first to postulate a lipid-bound D-glucose as an intermediate in the biosynthesis of bacterial cellulose. Lipid-sugar derivatives, tentatively identified as lipid-diphosphate-D-glucose, lipid-diphosphate-cellobiose, and, perhaps, higher polymers, were detected in this system.128 These lipid-sugar compounds, which were acid- and alkali-labile, seemed to be formed prior to cellulose, and their formation was inhibited by adding... 

Nakagaito AN, Yano H (2008) Toughness enhancement of cellulose nanocomposites by alkali treatment of the rein- forcing cellulose nanofibres. Cellulose 15 323-331 Nakagaito AN, Iwamoto S, Yano H (2005) Bacterial cellulose the ultimate nano-scalar cellulose morphology for the production of high-strength composites. Appl Phys A Mat Mater Sci Process 80 93-97... 

Numerous ethers of cellulose, starch, and bacterial dextran are of established or potential industrial importance. (See also Chapter XII.) Treatment of the polysaccharides with alkali and methyl chloride, ethyl chloride, benzyl chloride, ethylene oxide (or ethylene chlorohydrin), sodium chloro-acetate, and allyl bromide gives, respectively, the methyl, ethyl, benzyl, hydroxy ethyl, carboxy methyl, and allyl ethers. The cellulose derivatives... 

Natural products are a mixture of these two modifications. Cellulose Ip is dominant in plants and wood, and the percentage of cellulose present varies depending on the species and the treatments. For example, the cellulose Ip content of cotton linter and ramie is 77%. Cellulose I transformed into cellulose Ip by a hydrothermal treatment in an alkali solution or by heat treatment at 280 °C in an inert gas. For example, Horii et al. reported that cellulose Ip content increases to 90% by heat treatment at 260°C in 0.1 M NaOH aqueous solution [21]. This indicates that cellulose Ip is thermodynamically more stable than cellulose Almost pure cellulose Ip is obtained from tunicates Halocynthia roretzi). Cellulose h is reported to be the major component of bacterial and algal cellulose. The structural difference between I and Ip is said to be brought about by shear stress during biosynthesis of cellulose microfibrils. 

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