Cellulose description

Solution Process. With the exception of fibrous triacetate, practically all cellulose acetate is manufactured by a solution process using sulfuric acid catalyst with acetic anhydride in an acetic acid solvent. An excellent description of this process is given (85). In the process (Fig. 8), cellulose (ca 400 kg) is treated with ca 1200 kg acetic anhydride in 1600 kg acetic acid solvent and 28—40 kg sulfuric acid (7—10% based on cellulose) as catalyst. During the exothermic reaction, the temperature is controlled at 40—45°C to minimize cellulose degradation. After the reaction solution becomes clear and fiber-free and the desired viscosity has been achieved, sufficient aqueous acetic acid (60—70% acid) is added to destroy the excess anhydride and provide 10—15% free water for hydrolysis. At this point, the sulfuric acid catalyst may be partially neutralized with calcium, magnesium, or sodium salts for better control of product molecular weight. 

Acetate—cellulose acetate. When not less than 92% of the hydroxyl groups are acetylated, triacetate may he used as a generic description. 1.2-1.5 G F P G G 1.33 210... 

The angle of the fibrils and the content of cellulose determine the properties of the plant fibers. The Hearle et al. s model [19] considers only these two structure parameters. For the description of stiffness, solely, the St layers were considered because the properties of these fibers were decisively dominated by the amount of these layers. 

Surprisingly the water consumption of a starter battery, provided it contains anti-monial alloys, is affected by the separator. Some cellulosic separators as well as specially developed polyethylene separators (e.g., DARAMIC V [76]) are able to decrease the water consumption significantly. The electrochemical processes involved are rather complex and a detailed description is beyond the scope of this chapter. Briefly, the basic principle behind the reduction of water loss by separators is their continuous release of specific organic molecules, e.g., aromatic aldehydes, which... 

In the original process the cellulose nitrate itself was used as the fiber (hence its satirical description as mother-in-law silk ). The regenerating agent is ammonium hydrosulfide. The basic process was first demonstrated by J. W. Swan in London in 1885 but commercialized by Count L. M. H. B. de Chardonnet ( Father of the rayon industry ) in France in 1891 and operated there until 1934. The last working factory, that in Brazil, was burnt down in 1949. The other processes for making rayon fibers by regenerating cellulose ( viscose, cupram-monium) gave superior products. See also Rayon. 

Description Percent alpha cellulose Percent accessibility... 

Structure 9.1 is most commonly employed as a description of the repeat unit of cellulose but structure 9.2 more nearly represents the actual three-dimensional structure with each D-glucosyl unit rotated 180°. We will employ a combination of these two structural representations. Numbering is shown in structure 9.3 and the type of linkage is written as 1 4 since the units are connected through oxygen atoms contained in carbon 1 and 4 as shown in structure 9.3. 

The driving force behind the great scientific interest in copolymer science and technology, js the search for products with useful, new or interesting properties. This monograph provides an informative account of new, improved cellulosic materials and the chemistry and technology involved in their production, as well as the first detailed description of grafted and modified celluloses. 

For the prepn of AEG with a N content of ca 20%, BRL treated a small amt of cellulose with a large excess of ethyleneimine in a bomb reactor at 160-200° for 6—20 hrs and recycled the product 2 or 3 times under the same conditions to get a higher N content (Refs 2 3) Later work(Ref 4) raised the N content to a max of 28.8%. This material was used for the prepn of fast burning salts, such as the perchlorates and nitrate. A detailed description of the prepn of high nitrogen AEC is given in Ref 4, Rept No l,p 6... 

In the following section information is given about the industrial methods of obtaining cellulosic raw materials, such as cotton and wood pulp cellulose, for the purposes of nitration. The question is discussed more extensively in special handbooks devoted to the technology of cellulose. For this reason the description that follows will be limited to general information only. 

The exact composition of mixed acids and the cellulose to acid ratios are included in the detailed descriptions of particular methods of nitration. 

A manufactured fiber in which the fiber-forming substance is cellulose acetate. Where not less than 92 lb of the hydroxyl groups are acelylaied, the term triaeetme may be used as a generic description of the fiber. A portion of the molecule may appear as ... 

PULP (Wood) PRODUCTION AND PROCESSING. Pulps can be defined as fibrous products derived from cellulosic fiber-contaiumg materials and used in the production of hardboard, fiberboard, paperboard, paper, and molded-pulp products. With suitable chemical modification, pulps can be used in Hie manufacture of rayon, cellulose acetate, and other familiar products. Pulps can be produced from any material containing cellulosic fiber but in North America and several other regions of the world, wood is the predominant source of pulp. This description is confined to the production and processing of wood pulp,... 

CA 31, 539(l937)(Nitration of cellulose in presence of wetting agents) 118)A.Foulon, SS 32, 348(l937)(Description of Hercules method of digesting NC as appeared in GerP 613063 of 1937) 119)M.G.Milliken, USP 2103592(1937) (Stabilization of NC by continous method) 120)... 

Continuous methods have also been developed for manuf of expls other than NG. As examples may be cited nitration plants for benzene (Refs 5 6a) aromatic hydrocarbons other than benz (Refs 7, 13 16) PE (Refs 17, 19, 21, 21b 22) DEG (Refs 21, 22 28) various org compds (Ref 36) cellulose, starch, sugar, etc (Ref 21) methyl nitrate (Ref 23a), etc. A continuous method for manufg propellants is described in Ref 46. A continuous method for manuf of TNT by the method of Bofors was installed in 1955 at the Fabrica Naval de Explosivos, Azul, Argentina (Ref 34a) Description of Some Continuous Methods for Manufacturing Explosives. 

A continuous vapor-phase nitration of cellulosic material in the form of a sheet was developed in the USA by the Brown Paper Co, Berlin, New Hampshire. No description of this method is available Refs l)J.Downie, BritP 1813 (1864) A-Nobel,... 

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