Nitrocellulose determination

Earlier authors Wehrhahn [23] and Mosenthal [24], assumed that the specific gravity of nitrocellulose determined in water is independent on the nitrogen content, and is 1.66. For cellulose in alcohol, Mosenthal reports the value 1.56-1.58. The specific gravity of nitrocelluloses of different nitration degree has been determined by Brunswig [25]. 

Polymerization degree of nitrocellulose (determined by measuring the viscosity of acetone) 77 170 220 440 670 1360 2500... 

Black Powder. Black powder is mainly used as an igniter for nitrocellulose gun propellant, and to some extent in safety blasting fuse, delay fuses, and in firecrackers. Potassium nitrate black powder (74 wt %, 15.6 wt % carbon, 10.4 wt % sulfur) is used for military appHcations. The slower-burning, less cosdy, and more hygroscopic sodium nitrate black powder (71.0 wt %, 16.5 wt % carbon, 12.5 wt % sulfur) is used industrially. The reaction products of black powder are complex (Table 12) and change with the conditions of initia tion, confinement, and density. The reported thermochemical and performance characteristics vary greatly and depend on the source of material, its physical form, and the method of determination. Typical values are Hsted in Table 13. 

The problem of solvent selection is most difficult for high molecular-weight polymers such as thermoplastic acryHcs and nitrocellulose in lacquers. As molecular weight decreases, the range of solvents in which resins are soluble broadens. Even though solubihty parameters are inadequate for predicting ah. solubhities, they can be useful in performing computer calculations to determine possible solvent mixtures as replacements for a solvent mixture that is known to be satisfactory for a formulation. 

If chloride is present, saturated aqueous silver acetate solution should be added in amounts slightly more than the calculated quantity prior t o the addition of concentrated sulphuric acid. The procedure may be applied to the routine analysis of mixtures of nitric and sulphuric acids, and to the determination of nitrogen in esters such as nitroglycerine and nitrocellulose the latter are easily hydrolysed by strong sulphuric acid after dispersal in glacial acetic acid. 

Carter et al, Modified Devarda Method for the Determination of Nitrogen in Nitrocellulose ,... 

Cellulose Chemistry , London (1947), 245—47 22) B.T. Fedoroff, Rapid Method for the Determination of Nitrogen Content of Nitrocellulose by the Ferrous Ammonium Sulphate Method , PACLR 122871 (1948) 23) J. Pearson... 

FIGURE 5. Assay for Met(0)-peptide reductase. The assay for Met(OJ-peptide reductase is carried out in a two-step incubation. The first incubation mixture contains Met(OJ-L12, DTT and the Met(OJ-peptide reductase. At the end of this incubation, purified L12 transacetylase and [3H]acetylCoA are added and the amount of radioactivity incorporated into L7 is determined by its ability to be retained on a nitrocellulose filter. The latter represents the amount of Met(0)-L12 reduced since the oxidized protein is not a substrate for the transacetylase. 

Many methods have been proposed and are used to study the thermal stability of propellants and to ensure the absence of possible autocatalysed decompositions during storage. None are sufficiently reliable to merit individual description. In practice, stabilisers are added, the usual being diphenylamine for nitrocellulose powders and symmetrical diethyl diphenyl urea (carbamate or centralite) for double base propellants. Provided a reasonable proportion of stabiliser remains, the propellant can be assumed to be free from the possibility of autocatalytic decomposition. The best test of stability is therefore a chemical determination of the stabiliser present. 

Antibodies may also be used to determine the presence or identity of soluble antigens by a process known generally as immunoblotting. In a technique known as dot blotting , soluble antigens are applied to a nitrocellulose membrane in the form of dots , antibody is then applied to the membrane, the membrane is washed to remove unbound antibody, and the presence or absence of the antigen is determined by similar means to that employed during immunohistochemistry. 

Note. All of the RDX component and portions of the TNT and wax are added as Composition B. A separate calcium chloride determination need only be 9one if required in the contract or order (See 6.2). Percentage requirement of Calcium Chloride is 0.5% 0.1% Calcium Silicate shall be determined as specified in 4.4.1.2 when used in the formulation of HBX compounds. The Calcium Silicate content shall be a minimum of 1.25 weight percent of the TNT content of the mixture and shall only be used in the HBX compositions when specified by the procuring agency (See 6.2). Calcium Silicate is designated for use only in Army formulations of HBX type explosive compositions. The major portion of the wax and all of the Nitrocellulose and lecithin are added as Composition D-2 ... 

Determination of RDX + Nitrocellulose. The percentages of TNT, Ca chloride, aluminum, and wax + lecithin are added and their sum subtracted from 100 percent. The remainder is taken to be the percentage of RDX plus Nitrocellulose... 

Alternate Method of Analysis. Grade A 4.4.3.3.1 Determination of RDX + Nitrocellulose. Weigh accurately a sample calculated to contain between 0.35 and 0.40g of TNT into a tared 100-ml beaker. Add 20ml of RDX saturated benzene to the beaker. The prepn of the RDX saturated benzene is described in 4.4.3.5.5. Cover beaker with a watch glass and place on a steam bath for 30 mins, swirl soln frequently. (An oscillating hot... 

Ethanol, Ether, Acetone and Water Determinations in Nitrocelluloses and Smokeless Propellants as Described in the Literature ... 

Solvent amount. The amount is largely determined by the amount of nitrocellulose in the composition. Figure 3 provides an example of the effect of solvent composition and amount on density. 

Amido black dye Two years later, Grassman and Hanning developed another organic dye to be used on filter paper after electrophoresis amido black stain. It has moderate sensitivity. Today, amido black dye is used for colorimetric determination of electroblotted proteins on PVDF (poly-vinylidene difluoride) and nitrocellulose membranes. 

Figure 3.5b shows data for a sample of nitrocellulose in three different solvents. All show the same intercept corresponding to a single molecular weight as required. Note, however, that the slopes are different, including even a negative slope, indicating that wide variations in B are possible. We examine the factors that determine B in Section 3.4. 

By determining their chemical stability and ignition temperature, e.g. the stability of nitroglycerine- or PETN-, or nitrocellulose-nitro compound mixtures (Vol. IT, pp. 49, 181 and Vol. Ill, p. 566, respectively) [7],... 

The majority of the stability tests for smokeless powder are much the same as the methods used to determine the stability of nitric esters, in particular nitrocellulose (Vol. II). They are based on heating samples of the powder, thus starting decomposition processes or hastening processes already initiated within the powder. The value of such methods is comparative, since at an elevated temperature different reactions occur than those which would arise under normal conditions of storage. Nevertheless experiments over many years have shown that certain interrelations may be established for the stability of powder at various temperatures. Vieille [61] reports that the heating of a sample of powder for 1 hr at a temperature of 110°C involves approximately the same decomposition as ... 

More recently Demougin and Landon [67] examined the stability of nitrocellulose powder containing 1.02-7.8% diphenylamine at a temperature of 110°C. After 160 hr of heating they determined the nitrogen content in nitrocellulose isolated from powder (Table 174.). The initial content of diphenylamine in the sample was 7.8% on heating for 180 hr at a temperature of 110°C it was reduced to 1%. 

The volatile solvent (alcohol-ether mixture) is used in such an amount that the dough is fairly loose but sticks when pressed between the fingers. The actual amount depends to a great extent on the properties of the nitrocellulose, since some forms require more solvent than others. The amount of solvent is usually determined by experiment. It ranges from 70-150 parts per 100 parts by weight of a mixture of nitrocellulose (dry substance). 

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