Cellulose nitrate development

Blending technology developed slowly. The third processable polymer of the nineteenth century was cellulose nitrate, developed by Schonbein [20] as an explosive. An 1855 patent by Parkes [21] describes the blending of natural rubber and guttapercha with a solution of cellulose nitrate, and fabricating the resultant sheets for various applications. 

There was significant interest in developing commercial processes based on phenolic resins in the 1890-1910 era. By this time, cellulose nitrate, vulcanized rubber, and viscose rayon had all found places in commerce [24]. Smith patented processes for manufacture of commercially useful molded articles from phenolic in 1899-1900 [2,25-28]. His products were made with phenol, paraldehyde (2,4,6-trimethyl-1,3,5-trioxane) or parafonnaldehyde, and additives in the presence of HCl at elevated temperatures. 

Refs to nitrated materials, eg Cellulose Nitrate, Cyclonite etc., already described in this Encyclopedia will be found in Sections 11 111 In view of the definition of nitration presented above and the concepts to be developed in Section VIII, discussion of nitrate salts such as H2NNH2.HNG3 or CH3NH2.HN03 etc is not included in this article... 

Tape >System of Analysis. A tape system which is used widely for analysis in the Pediatric Laboratory is a system whose principle was developed by the author. A reagent is placed on a paper tape. The paper is covered with a membrane, such as cellophane, cellulose nitrate or cellulose acetate, porous to low molecular weight substances. Finally, the serum is placed above the porous membrane, so that diffusion of the components of serum take place and a stain is produced on the paper (60). This principle has been incorporated for example, with glucose oxidase, in the conmercially available Dextro-Sticks. In addition, a similar principle is being applied by some for the analysis of components in urine (Ames Co., South Bend, Indiana). 

An early generation of composite membranes, developed by Riley, et al. (21), was based on cellulose triacetate (CTA) cast in an ultrathln coat from chloroform on the finely porous surface of a cellulose nitrate/cellulose acetate substrate. These membranes did not reflect a need for a hydrophllic-gel Intermediate layer. Yet, this membrane substrate is much more hydrophilic than the rejecting CTA layer, and high flux as well as high separation were concurrently obtained. This is not the case if the porous substrate is highly hydrophobic. A rejecting layer deposited on such a surface would yield an extremely poor productivity due to the loss of... 

A cooler-burning pyrotechnic composition based on cellulose nitrate and guanidine nitrate has been developed which produces reaction temperatures of less than 500 °C, thus causing less destruction of the dye. 

Although Lhe first cellulose plastic (cellulose nitrate plastic-based on an inorganic ester of cellulose) was developed in 1865. the first organic cellulose ester plastic was not offered commercially until 1927. In that year, cellulose acetate plastic became available as sheets, rods, and tubes. Two years later, in 1929. it was offered in the form of granules for molding. It was the first thermoplastic sufficiently stable to be melted without excessive decomposition, and it was the first thermoplastic to be injection molded. Cellulose acetate butyrate plastic became a commercial product in 1938 and cellulose propionate plastic followed in 1945. The latter material was withdrawn after a short time because of manufacturing difficulties, but it reappeared and became firmly established in 1955. 

Enzyme micro-encapsulation is another alternative for sensor development, although in most cases preparation of the microcapsules may require extremely well-controlled conditions. Two procedures have usually been applied to microcapsule preparation, namely interfacial polymerization and liquid drying [80]. Polyamide, collodion (cellulose nitrate), ethylcellulose, cellulose acetate butyrate or silicone polymers have been employed for preparation of permanent micro capsules. One advantage of this method is the double specificity attributed to the presence of both the enzyme and the semipermeable membrane. It also allows the simultaneous immobilization of many enzymes in a single step, and the contact area between the substrate and the catalyst is large. However, the need for high protein concentration and the restriction to low molecular weight substrates are the important limitations to this approach. 

The first major application of microfiltration membranes was for biological testing of water. This remains an important laboratory application in microbiology and biotechnology. For these applications the early cellulose acetate/cellulose nitrate phase separation membranes made by vapor-phase precipitation with water are still widely used. In the early 1960s and 1970s, a number of other membrane materials with improved mechanical properties and chemical stability were developed. These include polyacrylonitrile-poly(vinyl chloride) copolymers, poly(vinylidene fluoride), polysulfone, cellulose triacetate, and various nylons. Most cartridge filters use these membranes. More recently poly(tetrafluo-roethylene) membranes have come into use. 

Membranes and composites from cellulose and cellulose esters are important domains in the development and application of these polymer materials. The most important segment by volume in the chemical processing of cellulose contains regenerated cellulose fibers, films, and membranes, hi the case of the cellulose esters mainly cellulose nitrate and cellulose acetate as well as novel high-performance materials created therefrom are widely used as laminates, composites, optical/photographic films and membranes, or other separation media, as reviewed in [1], The previously specified nanocelluloses from bacteria and wood tie in with these important potentials and open novel fields of application. 

As a matter of fact, mankind knows polymers from ancient times, due to the existence of naturally occurring polymers such as latex, starches, cotton, wool, leather, silk, amber, proteins, enzymes, starches, cellulose, lignin, and others. The other type of polymers are synthetic polymers. Braconnot, in 1811, perhaps made the first significant contribution to polymer science by developing compounds derived from cellulose. Later, cellulose nitrate was obtained in 1846 by Schonbein, afterward in 1872, its industrial production was established. Besides, in 1839, Goodyear found out by accident that by heating latex with sulfur its properties were altered creating a flexible and temperature-stable rubber. This process is named vulcanization. 

The industrial change and expansion of the nineteenth century had many strands and among them attention was given to man-made replacements for resinous compositions and horn. Alexander Parkes, a prolific inventor and manufacturer, was involved closely with the search for commercial materials he showed articles of Parkesine (a cellulosic) at the Universal Exhibition in London in 1862. Further investigations and development led eventually in Britain, Germany, the USA, and elsewhere to the industry based on a cellulose nitrate plasticized with camphor and (somewhat later) to cellulose acetate and to other cellulose plastics (cellulose acetate butyrate, ethyl cellulose, etc.). 

Historically, plasticizers played a crucial role in the development of the first plastic—celluloid. In Chapter 4 we saw that Hyatt, Parkes, and Spill formulated cellulose nitrate with camphor to produce a solid that could be fabricated into hard, useful, and attractive objects. Camphor is a relatively... 

Polyvinyl chloride (PVC) and polyvinyl acetate (PVA) are considered to be the first synthetic polymers created. Safe-handling cellulose acetate soon replaced explosive cellulose nitrate. Polyacrylonitrile and polyamides (Nylon) soon followed. American companies such as DuPont pioneered the development of plastics. England was responsible for the early development of polyester polymerization. 

Many cellulose esters, such as cellulose nitrate, cellulose acetate, and mixed esters of cellulose acetate butyrate, have found popularity in commercial scale production. Many new esters continue to appear in the market. Traditionally, esterification is conducted on a heterogeneous system (topo-chemical reaction) however, homogeneous systems employing mixed organic solvents have recently been developed. For example, Ikeda et al. [17] demonstrated that homogeneous esterification and acetalization of cellulose in LiCF DM AC can be achieved. 

Celluloid was one of the early plastics that was used in numerous ways. It was made of cellulose nitrate and was extremely combustible, but a safer version, cellulose acetate, was later developed. Dyed black, they are reasonable imitations of jet but th have a plasticy look and feel. Black celluloid gives a fldnt, black streak. Baikelite, or phenol formaldehyde, could be dyed any colour and was widely used. When dyed black, it was also a reasonable jet imitation, but it dulls with age and has a plasticl look and feel. Black Bakelite gives a black streak. 

Cellulose nitrate is a semi-synthetic plastic based on cellulose from wood or cotton. It is mixed with nitric and sulphuric acids, and uses camphor as a plasticiser. It is another compound that was being developed by various people in different places at the same time, but was launched in England in 1862 as Parkesine . It was later called Xylonite . Cellulose nitrate was finally patented in America in 1870 under the name celluloid , but has been known by over 60 different trade names during the years it has been in production. 

Cellulose acetate was developed in 1894 as a safe alternative to the combustible cellulose nitrate. It was made with acetic acid instead of nitric acid. It was not put into commercial production until the 1920s - after the First World War - when it was called rayon . If not kept in ideal conditions it can, in rare cases, degrade, giving off a smell of vinegar. 

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