Cellulose history

The chemical and physical properties of cellulose depend ia large measure on the spatial arrangements of the molecules. Therefore, cellulose stmctures have been studied iatensively, and the resulting information has been important ia helping to understand many other polymers. Despite the extent of work, however, there are stiU many controversies on the most important details. The source of the cellulose and its history of treatment both affect the stmcture at several levels. Much of the iadustrial processiag to which cellulose is subjected is iatended to alter the stmcture at various levels ia order to obtain desired properties. 

Activation of Cellulose. The activation required depends on the source of cellulose (cotton linter or wood pulp), purity, and drying history. Typical specifications for an acetylation-grade cellulose are given in Table 5. Cellulose that has never been dried or has been mildly dried to ca 5% moisture requires Htde, if any, further activation. 

Tliere is another type of application where the damping effect of plastic structures can be used to advantage. It has a long although not obvious history. The early airplanes used doped fabric as the covering for wings and other aerodynamic surfaces. The dope was cellulose nitrate and later cellulose acetate that is a damping type of plastic. Conse-... 

Indeed it can be stated that the history of modern expls begins with the discoveries of nitroglycerin (NG) and nitrocellulose (or more correctly cellulose nitrate or NC) nearly 125 years ago, and their application to military and commercial usage. An excellent review of the early history of NC is given by. T.L. Davis (Ref 29, pp 244—56). The early histories of NG and EGDN (discovered in 1870) are summarized, respectively, in Vol 6, G99-R to G100-R and E259-R, and in the Naoum reference cited above... 

The history of the achievement of present-day understanding of the constitution of cellulose has been splendidly presented by C. B. Purves in Chapter II, A, of Cellulose and Cellulose Derivatives, ed. by Emil Ott (Interscience Publishers, New York, 1943), pp. 29-53. The author takes pleasure in acknowledging indebtedness to this source. 

Pervaporation Membranes Pervaporation has a long history, and many materials have found use in pervaporation experiments. Cellulosic-based materials have given way to polyvinyl alcohol and blends of polyvinyl alcohol and acrylics in commercial water-removing membranes. These membranes are typically solution cast (from... 

History. Starting from the ID point statistics of Zernike and Prins [116] J. J. Hermans [128] designs various ID statistics of black and white rods. He applies these models to the SAXS curves of cellulose. Polydispersity of rod lengths is introduced by distribution functions, / , (,r)108. Hermans describes the loss of correlation along the series of rods by a convolution polynomial . One of Hermans lattice statistics is namedparacrystalby Hosemann [5,117]. Hosemann shows that the field of distorted structure is concisely treated by the methods of complex analysis. A controversial subject is Hosemann s extension of ID statistics to 3D [63,131,227,228],... 

A basic scientific investigation of fire retardancy, however, remained to be initiated by Gay-Lussac in France at the request of King Louis XVIII in 1821 who was again interested in reducing the flammability of theater curtains. This researcher noted that the ammonium salts of sulfuric, hydrochloric and phosphoric acids were very effective fire retardants on hemp and linen and that the effect could be improved considerably by using mixtures of ammonium chloride, ammonium phosphate and borax. This work has withstood the test of time and remains valid to this day. Thus the basic elements of modern fire retardant chemistry had been defined early in recorded history and remained the state of the art until early in the twentieth century. The most effective treatments for cellulosic materials being concentrated in Groups III, V and VII elements. 

China. See also People s Republic of China acrylic fiber production in, 11.T89, 220 adhesive joint ventures, 1 526 advanced materials research, 1 696 aquaculture history, 3 183 aquaculture production, 3 189t ascorbic acid synthesis in, 25 754 demand for oil in, 23 530 nanocomposite development, 1 717 natural graphite in, 12 780 oil recovery program in, 23 534 olefin fiber production in, 11 243 production and consumption of regenerated cellulose fibers in,... 

Cellulose is found in nature in combination with various other substances, the nature and composition of which depend on the source and previous history of the sample. In most plants, there are three major components cellulose, hemicelluloses, and lignin. Efficient utilization of all three components would greatly help the economics of any scheme to obtain fuel from biomass. Hemicelluloses, lignocellulose and lignin remaining after enzymatic degradation of the cellulose in wood would require chemical or thermal treatment - as distinct from biochemical - to produce a liquid fuel. 

In North America the problem of moisture absorption has been addressed by developing a moisture resistant gunpowder substitute based on potassium nitrate but augmented with potassium perchlorate. The latter is said to absorb less moisture than the nitrate at a given humidity. In addition, the gunpowder substitute contains a hydrophobic binder, called ethyl cellulose, (2.22) (celluloses have a history of use in pyrotechnics) together with an organic fuel, known as phenolphthalein, (2.23) which is said to enhance the bum rate. 

Throughout human history a limited number of fibers provided the fabric used for clothing and other materials—wool, leather, cotton, flax, and silk. As early as 1664, Robert Hooke speculated that production of artificial silk was possible, but it took another two hundred years before synthetic fibers were produced. The production of synthetic fibers took place in two stages. The first stage, started in the last decades of the nineteenth century, involved chemical formulations employing cellulose as a raw material. Because the cellulose used in these fibers came from cotton or wood, the fibers... 

The most important azo compounds employed in the manufacture of dyes of this type are those containing the < ,o -dihydroxyazo-, the o-hydroxy-o -carboxyazo- and the o-hydroxy-o -amino-diarylazo systems. It is well established3 33-0 that these form four-coordinate copper and nickel complexes (35) in which the coordination sphere of the metal can be completed by a variety of neutral ligands. In both cases the light-fastness of the parent azo compound is improved as a result of complex formation but the nickel complexes are insufficiently stable towards acid to be of commercial interest as dyestuffs. The history of copper complexes has already been discussed (Section 58.1) and will not be considered further here, although it is worthy of mention that currently the most important copper complex dyestuffs are those containing fibre-reactive systems, e.g. (36), for application on cellulosic fibres. 

These compositional considerations necessitate attention to raw materials evaluation early in process research and development to (1) establish an in-depth knowledge of the principal raw material, including its composition and history of materials handling prior to arrival at the factory, (2) investigate the effects of seasonal variations and storage under various conditions on composition and on hydrolytic performance, and (3) explore alternative pretreatment processes for upgrading the composition and hydrolytic performance of available raw materials. The resource that is for sale is not pure cellulose it is a complex mixture containing cellulose caveat emptor. 

This symposium presented an unusual opportunity in that we discussed the methods used to determine polymer structures from fiber diffraction data, rather than concentrating on the actual structures derived and their possible implications. At Case Western Reserve University we have been involved in determination of the structures of cellulose and chitin. This paper describes our analyses (1-6) of the structures of cellulose I and II and a- and 6-chitin, emphasizing the manner in which structural decisions were taken in each case. Efforts to determine these structures have a history of over 60 years, and it has only been with the advent of least squares techniques for the refinement of polymer structures (7) [notably the LALS method (8)], and the development of our present knowledge of polysaccharide stereochemistry, that solutions have become possible. In what follows we will look first at our methods for measuring intensities and thereafter will review the work on each of the four structures. 

Cellulose is the main structural element of the cell walls of most plants and is also a major component of wood, as well as cotton and other textile fibers, such as linen and hemp. The history of cellulose is as old as that of humankind. For instance, fine clothes and cottons have been recovered from the tombs of the ancient kings of Egypt, the pharaohs. Today, cellulose and its derivatives are used in the industrial preparation of paper and also in the chemical industry as a stabilizer, dispersing agent, thickener, and gelling agent. Cellulose is also a component of dietary fiber. 

Saccharification of cellulosic biomass by dilute acid has a much longer history than the enzymatic process. The initial acid-catalyzed wood saccharification was in operation in Germany as early as the 1940s (1). In recent... 

---