Low-viscosity nitrocellulose

Effect of the conditions of nitration. The conditions under which the nitration was carried out exert an appreciable influence on the viscosity of nitrocellulose solutions. Thus a high nitrating temperature produces low viscosity nitrocellulose... 

Similar results due to irradiation were also established by Rogovin and Glas-man [90]. Clement, Riviere and Beck [91] found that under the influence of the light only the viscosity of high-viscosity nitrocellulose was decreased, low-viscosity nitrocellulose did not undergo any change. In view of the experiments of Mine [92], quoted below, this observation appears to be inaccurate. Clement, Riviere and Beck observed, moreover, that the solubility was increased by irradiation. The increase of solubility may be brought about to some extent by a certain denitration... 

During World War II the Germans used TNT/nitrocellulose cast propellant (VoL HI, p. 681). A similar propellant was developed by T. Urbahski (41) in Great Britain during World War II. U was composed of TNT, low viscosity nitrocellulose, potassium nitrate and aluminium. 

Low-viscosity nitrocellulose is used to prepare high-solids lacquers. Since low-viscosity nitrocellulose produces hard to brittle coating films, plasticizers and plastify-ing resins must be added to the lacquer formulation. They are used in putty, dipping paints, and printing inks. 

When a major portion of Guncotton was dispersed with acetone-alcohol and the residual portion with one of the above compds, equal weights of the compds were superior to dibutyl phthalate and to triacetin first, with respect to time reqd for complete dispersion and secondly, in producing solns of low viscosity Ref A.J. Philips, The Relation of the Hydrogen Bonding Concept to the Gelatinization of Nitrocellulose, PATR 1249 (March 1943)... 

Fedoroff, "Basic Research Leading to the Development of Ideal Propellants. Preparation of Low Viscosity, High Nitrogen Nitrocellulose , PATR 1678 (Feb 1948)... 

With wood nitrocellulose smaller amounts of solvent are used (70-90%). This is accounted for by the lower degree of polymerization of wood cellulose in comparison with that of cotton. With its lower degree of polymerization wood nitrocellulose swells and dissolves more readily, producing solutions of a relatively low viscosity. 

Finely ground nitrocellulose of low viscosity was used. It was impregnated with DGDN under water in the usual way. After dehydration in a centrifuge to a moisture content of 18-22%, the blend was stirred into molten TNT. The vat was evacuated to evaporate the water and to produce a homogeneously gelatinized grain. 

As shown experimentally by Piest [75], cotton which was subjected to various operations, e.g. bleaching, treatment with alkalis or acids, strong heating prior to nitration furnishes nitrocellulose solutions of low viscosity. At the same time an increase in the solubility of the nitrocotton was also observed. This is evidence that the cellulose molecules are shortened and their content of terminal group is increased. A certain proportion of hydrocellulose and oxycellulose may result. The total effect is to bring about an increase in the reductive properties of the cellulose, i.e. an increase of the copper number. 

Fig. 106. Nitrogen contents of extracted nitrocellulose fractions according to G. G. Jones and Miles [16a] CO HH nitrocellulose, 12.20% N, high viscosity, unkiered (II) HX nitrocellulose, 12.26% N, low viscosity (III) HX nitrocellulose, 12.07% N, low viscosity (IV) Guncotton, unkiered, 13.14% N (V) Guncotton, kiered, 12.95% N (VI) Guncotton, kiered, 12.93% N (VII) Pyro nitrocellulose, 12.70% N (VUI) Nitro-woodpulp, 11.30% N (IX) Nitroramie (73.5% soluble...

Nitration. The nitration is usually carried out under conditions that promote the production of a low-viscosity product. Hence the process is carried out primarily with linters, at a relatively elevated temperature, commonly between 30 and 35°C. The clarity of nitrocellulose sulution increases, with nitration time to an optimum and then decreases [1]. 

Nitrocellulose of 11.8-12.3% N intended for celluloid manufacture is obtained in a way resembling the production of lacquer-grade material with the exception that the viscosity of the product is not of such decisive importance. Low viscosity of the nitrocellulose can cause the celluloid gel to be brittle, however. For this reason care should be taken to keep the viscosity above a certain limit. The essential stabilization can be carried out in boilers without recourse to autoclaves, but in order to shorten the stabilization process it is possible to carry out the kiering in autoclaves, the process then requiring only a few minutes. 

The viscosity of nitrostarch solutions is appreciably lower than the viscosity of the corresponding nitrocellulose solutions. Taking the viscosity of water as 100, the viscosity of 1% nitrostarch solutions varies within the relative values of 45 and 70. Due to such low viscosity and non-oriented crystal structure, nitrostarch solutions leave very fragile film after evaporation. Hence nitrostarch is valueless for varnish production, and for smokeless powder making. 

Continuous Digester far Nitrocellulose, patented by Milliken of Hercules Powder Co. has been used for manuf of NC of low viscosity, such as required for lacquers... 

T. Urbanski (I27j suggested recrystallization to add a protective colloid such as an acetone solution of nitrocellulose (low viscosity grade collodium cotton). 

OTHER COMMENTS used as a solvent for nitrocellulose, low viscosity cellulose acetate, natural and synthetic resins, some alcohol-soluble dyes, lacquers enamels and varnishes also used in dyeing leather, sealing moisture-proof cellophane, in nail polishes, and in wood stains useful as a jet-fuel deicing additive. 

High-viscosity, medium-viscosity, and low-viscosity formulations of each type are available [2.3]. Important producers of nitrocellulose used in lacquers include Hercules (USA), ICI (UK), BNC (France), Wolff Walsrode (FRG), and NQB (Brazil). 

Films formed from high-viscosity nitrocellulose have good flexibility combined with a high crack resistance. They are therefore employed where high mechanical stress is to be expected (e.g., in leather coatings, putty, adhesives). Only lacquers with low solids contents can be obtained from high-viscosity nitrocellulose. 

Isopropyl ocetote is a wofer-whife pleosont-odored liquid with properties intermediote between ethyl and butyl acetates. It is miscible with most of the common organic solvents such os alcohols, ketones, esters, oils, hydrocarbons, etc., and it is a solvent for nitrocellulose, cellulose ocetate (of low viscosity) and a wide ronge of oils, fats, waxes, gums ond notural and synthetic resins. Like n-propyl ocetote, its solvent power for cellulose esters is increosed when lower aliphatic alcohols are added. It is largely used in the lacquer industry where its slow evaporation rate and blush resistance ore of importance. It is also used in the monufacture of plastics, artificial leather, dopes, films, cements, and in the recovery of acetic ocid from aqueous solutions. 

Nitrocellulose lacquers can be formulated with a large number of ketone solvents. Acetone, a fast evaporating solvent, will tolerate large additions of cheaper aromatic diluents to the nitrocellulose lacquers. The low viscosity of acetone and the hydrocarbon additions affords low solution viscosities. Other ketones that are useful as nitrocellulose solvents and that have high aliphatic and aromatic dilution ratios include MEK and MIBK. Additional ketones that find use in nitrocellulose lacquers include methyl /i-amyl ketone, methyl isoamyl ketone, dipropyl ketone, diisobutyl ketone, and cyclohexanone. Selection of the ketone often will depend on the desired evaporation rate. 

All-purpose plasticizer for lacquers and vinyls. It is a plasticizer and processing aid for rubber compounds. It is a low volatility, low viscosity product which imparts exceptional cold crack resistance to flexible nitrocellulose lacquers. 

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