Soda cellulose

Soda cellulose IV, 5 379 Soda drossing process, 14 748 Sodalime silica (SLS) glass surface coatings, 12 608 Soda—lime silica glass,... 

Strong basic solutions, such as sodium hydroxide, penetrate the crystalline lattice of a-cellulose producing an alkoxide called alkali or soda cellulose. Mercerized cotton is produced by aqueous extraction of the sodium hydroxide. 

C6H1Q05)n (cellulose) + 18% aqueous NaOH - [(C6H1Q05)2 Na0H]n (swollen, insoluble, soda cellulose I) + soluble soda cellulose from j8 and y celluloses... 

The cellulose sheets are loaded vertically, but loosely, into a combination steeping bath and press (Fig. 12.6), which is slowly filled with a solution of 17-19 percent caustic, where they remain for about 1 hr. In the steeping, the alpha cellulose is converted into alkali or soda cellulose at the same time, as already mentioned, the caustic solution removes most of the beta and gamma cellu-... 

Cellulose xanthate, or more exactly, sodium cellulose xanthate or sodium cellulose dithiocar-bonate, is obtained by mixing the aged soda cellulose with carbon disulfide in a vapor-tight xanthating chum. Based upon weight of cellulose, the amount of carbon disulfide used will be in the range of 30 percent for regular rayon to 50-60 percent for modified varieties. 

Besides the cellulose structures I-IV and their subclasses, cellulose forms a variety of crystalline complexes. Soda celluloses were mentioned above, and there is an extensive array of complexes with amines [236]. Soda cellulose IV [237] is actually a hydrate of cellulose and contains no sodium (historically, cellulose hydrate meant cellulose II, which is now known to contain no water ). Many cellulose derivatives such as the nitrate (see above) and the triacetate [238] also give diffraction patterns. The most recent analysis of triacetate I shows a single-chain unit cell [239]. 

Ternary complexes called soda celluloses can form between cellulose, sodium hydroxide, and water [310]. In these complexes, some of the water molecules of the sodium hydroxide hydrates are replaced by the hydroxyl groups of the cellulose [310]. The x-ray diffraction diagrams have been obtained for five soda celluloses as intermediates in the formation of cellulose II from cellulose I [310,316]. 

With each of these materials the first step is the manufacture of alkali cellulose (soda cellulose). This is made by treating cellulose (either bleached wood pulp or cotton linters) with concentrated aqueous sodium hydroxide in a nickel vessel at elevated temperamre. After reaction excess alkali is pressed out, and the resultant cake is then broken up and vacuum dried until the moismre content is in the range 10-25%. The moisture and combined alkali contents must be carefully controlled as variations in them will lead to variations in the properties of the resultant ethers. 

The same phenomena were observed for soda celluloses. Na-oellulose Ij prepared from the I family under conditions of low swelling (high temperature or with stretching) could be converted to cellulose I with hot water. Na-cellulose Ijj prepared from cellulose II under the same conditions was converted to cellulose II (7-10). In ordinary mercerization of native cellulose a mixture of Na-cellulose Ij and Ijj was obtained both decomposed to cellulose II with cold water. Na-cellulose Ij was transformed irreversibly into Na-cellulose Ijj. 

There has been another proposal that plane-structures consisting of cellulose molecules in the lOl plane of native cellulose are held together by hydrophobic interactions even in the presence of alkali, and that hydrophilic surfaces of the 101 plane-structures are solvated with alkali and water (24). However, if such planar structures were solvated with aqueous alkali, they would be expected to result in the formation of a dispersion of micelles. It seems to us more likely that some strong or sterically protected inter-molecular hydrogen bonds of native cellulose survive even in alkali cellulose. On the other hand, since some hydrogen bonds are cleaved by NaOH and water which penetrate into the crystalline lattice of cellulose, new lattice planes can be formed as, for example, in Na-Cellulose I or other soda celluloses. 

Of cellulose ethers only ethyl cellulose has found application as a molding material. Methyl cellulose, hydroxyethyl cellulose, and sodium carboxymethyl cellulose are usefiil water-soluble polymers. The first step in the manufacture of each of these materials is the preparation of alkali cellulose (soda cellulose) by treating cellulose with concentrated sodium hydroxide. Ethyl cellulose is made by reacting alkali cellulose... 

Ethyl cellulose. A thermoplastic manufactured by reacting soda cellulose with chlo-roethane. Applications fire extinguisher parts, electrical components, flashlight bodies. Trade name Ampec (USA). 

Alkalicellulose soda cellulose, alkali cellulose Natronkalk soda lime Natronlauge/ Natriumhydroxididsung sodium hydroxide solution naturfern/... 

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