Cellulose derivatives, commercial

The numerous cellulose derivatives commercially available, displaying varying second order transition, molecular mass, viscosity, lyophilicity, thermotropic properties, have considerable potential. Significant advances have been made in the collection of fundamental data, but the interpretation of this information is somewhat more difficult than for synthetic polymers, mostly because of the heterogeneity of the materials, which exhibit a broad molecular mass distribution and an uneven substitution. 

Surface sizes are usually solutions of water-soluble polymers. The most important of which, because of its commercial cheapness, is starch. Other more costly but more specialised film-forming polymers such as soluble cellulose derivatives (particularly carboxy-methyl cellulose), polyvinyl alcohol and alginates are also used. 

Five types of commercial EtCell were manufd during WWII by the Hercules Powder Co (Ref 2), of which the N-Type, having 46.8 to 48.5% ethoxyl content, bad sp gr 1.14, mp 200—210° and the same requirements as were listed in USArmySpecification No 97—54—176, now replaced by Spec MIL-E-108 53 B. The product is more resistant to alkali solns than to the acids. Its flammability is of as low an order as any other cellulosic derivatives (Ref 2)... 

Among the gelling agents used are synthetic macromolecules as acrylic acid polymers such as Carbomer 934, cellulose derivatives such as carboxymethyl cellulose or hydroxypropylmethyl cellulose, and natural gums such as xanthan gum. Appendix IV shows the commonly used gelling agents in commercially available pharmaceutical gels. 

In addition to being necessary for all forms of life, biopolymers, especially enzymes (proteins), have found commercial applications in various analytical techniques. See also Automated Instrumentation Clinical Chemistry Automated Instrumentation Hematology and Biosensors. In synthetic processes (see also Enzymes in Organic Synthesis) and in prescribed therapies (See also Enzyme Therapeutic and Vitamin), Other naturally occurring biopolymcrs having significant commercial importance aie the cellulose derivatives, e.g., cotton and wood, which are complex polysaccharides. 

In spite of these enormous efforts, there is still no large-scale commercial application of cellulose graft copolymers. The reasons for this situation and the challenge it represents to cellulose and polymer scientists and engineers will be the subject of this introductory paper. It is convenient to break down such a discussion into the following areas, synthesis, characterization, properties and, finally, applications. The discussion will be mainly devoted to cellulose itself, although grafting to cellulose derivatives has also been actively pursued. 

Cellulose, the most abundant renewable agricultural raw material, is transformed into multifarious products affecting every phase of our daily life. The presence of active hydroxyl groups in cellulose has been utilized in a variety of chemical reactions to produce commercially important cellulose derivatives, such as cellulose ethers and cellulose esters. Although the practical purpose of cellulose derivatization is by and large to improve various properties of the original cellulose, these cellulose derivatives are often not competitive with most of the petrochemically derived synthetic polymers. In order to provide a better market position for cellulose derivatives, there is little doubt that further chemical modification is required. Grafting of vinyl monomers onto cellulose and... 

Materials. Cellulose and cellulose derivatives used for this study are summarized in Table 1. Commercial products were used as received without further purifications. Methyl methacrylate was used as the monomer, which was purified by sodium hydroxide/sodium chloride extraction followed by distillation under reduced pressure (10). 

The first man-made fibers of commercial importance were the cellu-losics. With respect to regenerated cellulose fibers, viscose rayon predominates. Between 1900 and 1967, world production of viscose rayon rose from 1000 tons to 2,700,000 tons (3). Cellulose derivative fibers did not go into commercial production until the 1920s. At that time cellulose acetate was manufactured. Cellulose triacetate fiber was brought into commercial production in the United States in 1954 (4). 

As discussed earlier, many cellulose derivatives are available commercially. Many review articles are also available on this subject. To avoid repetition of previous works, in what follows only unusual cellulose derivatives will be discussed. 

Early interest in the thermal degradation of cellulose was stimulated by lively academic discussions about the origin of bituminous coal — whether it is derived from the lignin or carbohydrate constituents of wood. This subject was also investigated in an attempt to determine the significance of cellulose in commercial destructive distillation of wood and its contribution to the mixture of degradation products. 

Alumina samples for investigation were prepared from aluminum hydroxide (Condea, type DISPERAL). A batch of aluminum hydroxide was kneaded either with water dematerialized solution of HNO3 (1%) or with water solution of cellulose derived product (commercial name CULMINAL), extruded with using of piston extruder, dried for 24 h at room temperature, then for 24 at 110 C and calcined for 4 h at 550, 650, 750, 800 or 850 "C). Obtained samples of alumina extrudates are described as DN (aluminum hydroxide "Disperal"... 

Of primary importance in the commercial use of cellulose derivatives are strength and toughness of the products. It was early recognized that these qualities were directly related to viscosity, and many com-... 

A variety of derivatives of cellulose are known and some of these have a large commercial production and use. Certain classes of cellulose derivatives can easily be recognized ... 

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