Plasticized cellulose nitrate

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 The latter material was withdrawn after a short time because of manufacturing difficulties, but it reappeared and became firmly established in 1955. 

Modern smokeless propellants for small arms ammunition almost exclusively contain plasticized cellulose nitrate (NC) as the major oxidizing ingredient (cellulose hexanitrate, commonly referred to as nitrocellulose). Various other chemicals are added for specific purposes ... 

Chemically modified cellulose in the form of cellulose nitrate or nitrocellulose was made and tested for commercial applications in Britain in the 1855-1860 period without much success. The discovery by Hyatt, in 1863, that cellulose nitrate could be plasticized with camphor to give moldability to the blend, made this material much more useful. By 1870, celluloid (plasticized cellulose nitrate) was being produced into a variety of commercial products such as billiard balls, decorative boxes, and combs. Nitrocellulose was also soluble in organic solvents, unlike cellulose, and so could be applied to surfaces in solution to form a coating, as in airplane dopes and automobile lacquers. It could also be solution spun into fibers (synthetic silk) and formed into photographic film, or used as a laminating layer in early auto safety glass. It was also used as an explosive. The hazard introduced to many of these uses of nitrocellulose by its extremely flammable nature resulted in an interest to discover other cellulose derivatives that could still be easily formed, like nitrocellulose, but without its extreme fire hazard. 

Alcohol resins, polyvinyl Alkyd resins Allyl resins Butadiene copolymers, containing less than 50 percent butadione Carbohydrate plastics Casein plastics Cellulose nitrate resins Cellulose propionate (plastics) Coal tar resins Condensation plastics Coumarone-iodene resins Cresol resins Cresol-furfural resins Dicyandiamine resins Diisocyanate resins Elastomers, nonvulcanizable (plastics)... 

It should be remembered that most museum objects have been used or displayed before they are collected. They have an unknown past, usually, which contributes greatly to the rate and type of deterioration. Instability of the earliest plastics, cellulose nitrate and acetate is expected due to their poorly stabilised formulations and because they are the oldest man-made plastics in museums. However, PVC was first developed in 1926 and is still in use, so its deterioration is rather unexpected. 

The history of plasticizers for man-made resins goes back to 18A6 when Schoenbein prepared cellulose nitrate, which provided the technology to make a resin that was amenable to plasticization (2). It was first plasticized by Alexander Parkes when he made "Parkesine," the forerunner of Celluloid (3 ). Parkes went on to produce various articles of plasticized cellulose nitrate. To modify their flexibility and hardness, he tried plasticizing the resin with oils, gums, paraffins, stearine, tar, glycerine, and other substances and varied proportions of those to his "pyroxy1ine." Cottonseed or castor oils were the preferred plasticizers cited in his master patent issued in 1865. 

Other solid material may be used as SSNTD instead of AgBr emulsions plastics (cellulose nitrate and polycarbonate films), glass, crystals, etc. In order to make the tracks visible in the microscope the surface of the SSNTD must be polished and etched, usually with alkali. 

The first completely synthetic plastic, phenol-formaldehyde, was introduced by L. H. Baekeland in 1909, nearly four decades after J. W. Hyatt had developed a semisynthetic plastic—cellulose nitrate. Both Hyatt and Baekeland invented their plastics by trial and error. Thus the step from the idea of macromolecules to the reality of producing them at will was still not made. It had to wait till the pioneering work of Hermann Staudinger, who, in 1924, proposed linear molecular structures for polystyrene and natural rubber. His work brought recognition to the fact that the macromolecules really are linear polymers. After this it did not take long for other materials to arrive. In 1927 poly(vinyl chloride) (PVC) and cellulose acetate were developed, and 1929 saw the introduction of urea-formaldehyde (UF) resins. 

The most important group of cellulose derivatives for thermoplastics application and the only one used commercially in this field is cellulose esters. Apart from camphor plasticized cellulose nitrate as the first thermoplastic (celluloid), acetate, propionate or butyrate, are the most common hydroxyl group substituents, as shown in Figure 3.5. 

Measurements of the saturated vapor pressures of plasticizers over plasticized cellulose nitrate were used for calculation of chemical potentials of plasticizers and partial enthalpies and entropies of mixing. ... 

Cellulose acetate and cellulose acetate butyrate are water-clear and more heat-resistant, but less wata"-resistant, than cellulose nitrate. Cellulose acetate butyrate has better heat and water resistance than cellulose acetate and is compatible with a wide range of plasticizers. Cellulose nitrate is tough, develops strength rapidly, is water-resistant, bonds to many surfaces, and discolors in sunlight. The dried adhesive (nitrocellulose) is highly flammable. ... 

Braconnet in 1833, is the oldest of the synthetic plastics. It is made by treating fibrous cellulose with a mbcture of nitric and sulfuric acids, and was first used in the form of a lacquer (See collodion). In 1870, John Wesley Hyatt and his brother patented the use of plasticized cellulose nitrate as a solid, moldable material, the first commercial thermoplastic (celluloid). Camphor was the first (and is still the best) plasticizer for CN, although many camphor substitutes have been developed. Alcohol is normally used as a volatile solvent to assist in plasticization, after which it is removed. Molded products of CN are extremely tough, but highly flammable and subject to discoloration in sunlight. CN is amendable to many decorative variations. Its principal uses today are in knife handles, table-teimis balls, and eyeglass frames. A mixture of nitric and sulfuric acids converts cellulose into cellulose nitrate pyroxylin is a less nitrated material and it has been useful for photographic film, collodion, and celluloid plastics. 

Parkesine n. The name given to the historic first (commercially unsuccessful) thermoplastic, made by plasticizing cellulose nitrate. The polymer was dissolved in a solvent, castor oil was mixed in, and the... 

Cellulose nitrate (CN) or nitrocellulose is a nitric acid ester of cellulose manufactured by the action of a mixture of sulfuric acid and nitric acid on cellulose, such as purified cotton linters. The major use of plastics-grade cellulose nitrate is in the coating field. Despite its disadvantages of flammability, instability, and poor weathering properties, cellulose nitrate is one of the cheapest and most highly impact-resistant plastic. It still has many uses because of these properties, including fountain pens, tool and brush handles, eyeglass frames, and some motion picture film. It accounts for only a small fraction of the volume of cellulose plastics. Cellulose nitrate materials are sometimes simply called nitrates. 

The early history of polymers is really the conversion of natural polymers into useful materials. Examples include the vulcanization of rubber (Goodyear, 1839), celluloid (which is plasticized cellulose nitrate—Hyatt, 1868), and cellulose-derived fibres, e.g. cuprammonia rayon (Despeisses, 1890) and viscose rayon (Cross, Bevan and Beadle, 1892). The first truly synthetic polymer, that is, one made from laboratory chemicals, was Bakelite (Bakeland, 1907). This was made from phenol and formaldehyde. Bakeland probably did not know the chemical structure of the Bakelite, but he did realize that organic chemicals containing multiple functionality yielded insoluble materials. The various phenol-formaldehyde resins (PF), e.g. Bakelite and novolacs, were thus obtained in an empirical manner. 

Plastics materials and resins), for example, acrylics, acrylonitrile-butadiene-styrene, alkyds carbohydrate, casein, and cellulose acetate plastics cellulose nitrates elastomers epoxy, ethylene-vinyl acetate, ion exchange, methyl cellulose, methyl methacrylate, nitrocellulose, nylon, polyacrylonitrile, polyamide, polycarbonate, polyester, polyethylene, polyethylene terephthalate, polyurethane, polyvinyl alcohol, polyvinyl chloride, silicone, urea, resins thermoplastics, thermosets... 

Golovin, V.A. and Lotmentsev, Yu.M., Investigation of structure and thermodynamie parameters of component interaction in plasticized cellulose nitrates, Vysokomolek. Soedin., 1981, vol. A23, no. 6, pp. 1310-1314 (in Russian). 

This does not mean we will see a mega-ton return to the old style polymers, such as casein plastics, cellulose nitrate and cellulose acetate. Many of these older polymers have severe deficits. For example, wool is eaten by moths and other insects cotton shrinks and does not hold a crease, unless treated with another polymer cellulose acetate is not solvent resistant, and cellulose nitrate is highly flammable. However, these older polymers come from renewable resources, which are also biodegradable, and this is a virtue in today s throw-away society. This alone should resurrect interest in natural polymers. Additionally, we have learned many vital things in the past century which will enable us to develop new and better polymers from biotechnology - polymers which... 

Cellulose nitrate, also called nitrocellulose or gun cotton, first became prominent after Christian Schonbein prepared it in 1846. He was quick to recognize the commercial value of this material as an explosive, and within a year gun cotton was being manufactured. However, more important to the rise of the polymer industry, cellulose nitrate was found to be a hard elastic material which was soluble and could be moulded into different shapes by the application of heat and pressure. Alexander Parkes was the first to take advantage of this combination of properties and in 1862 he exhibited articles made from Parkesine, a form of plasticized cellulose nitrate. In 1870 John and Isaiah Hyatt patented a similar but more easily processed material, named celluloid, which was prepared using camphor as the plasticizer. Unlike Parkesine, celluloid was a great commercial success. 

Cellulose Nitrates (CN). They are the source of the oldest thermoplastics, directly obtained from Nature (see Chapter 1), and were used in first instance to manufacture celluloid (camphor-plasticized cellulose nitrate) and then artificial silk as well as supports for photographic films. These applications were given up due to safety considerations but others appeared which still justify their significant production. 

---