Double-base

Trimethylolethane trinitrate (metriol trinitrate) is not satisfactory as a plasticizer for nitrocellulose, and must be used with other plasticizers such as metriol triacetate. Mixtures with nitroglycerin tend to improve the mechanical properties of double-base cast propellants at high and low temperatures. Metriol trinitrate has also been used in combination with triethylene glycol dinitrate as a plasticizer for nitrocellulose. Its physical properties are Hsted in Table 7 (118-122). 

W. G. Clark, Evaluation of 1,2,4-Butanetriol Trinitrate as the EiquidExplosive Plasticiserfor Cast Double Base Propellant Report 4, PTA, Dover, N.J., 1960. 

The Beckstead-Derr-Price model (Fig. 1) considers both the gas-phase and condensed-phase reactions. It assumes heat release from the condensed phase, an oxidizer flame, a primary diffusion flame between the fuel and oxidizer decomposition products, and a final diffusion flame between the fuel decomposition products and the products of the oxidizer flame. Examination of the physical phenomena reveals an irregular surface on top of the unheated bulk of the propellant that consists of the binder undergoing pyrolysis, decomposing oxidizer particles, and an agglomeration of metallic particles. The oxidizer and fuel decomposition products mix and react exothermically in the three-dimensional zone above the surface for a distance that depends on the propellant composition, its microstmcture, and the ambient pressure and gas velocity. If aluminum is present, additional heat is subsequently produced at a comparatively large distance from the surface. Only small aluminum particles ignite and bum close enough to the surface to influence the propellant bum rate. The temperature of the surface is ca 500 to 1000°C compared to ca 300°C for double-base propellants. 

Solventless Extrusion Process. The solvendess process for making double-base propellants has been used ia the United States primarily for the manufacture of rocket propellant grains having web thickness from ca 1.35 to 15 cm and for thin-sheet mortar (M8) propellant. The process offers such advantages as minimal dimensional changes after extmsion, the elimination of the drying process, and better long-term baUistic uniformity because there is no loss of volatile solvent. The composition and properties of typical double-base solvent extmded rocket and mortar propellant are Hsted ia Table... 

Table 8. Composition and Properties of Double-Base Solventless Propellant...

R. C. Strittmater, E. M. Wineholt, and M. E. Holmes, The Sensitivity of Double Base Propellant Burning Rate to Initial Temperature, MR-2593, BRL, Aberdeen, Md., 1976. 

D. Guide and D. H. Ensel, "Development of Spatial Laws of Burning for Single Base, Double Base and Heterogeneous Sohd PropeUant," in Fifth International Gun Propellant and Propulsion Symposium, ARDEC, Dover, N.J., Nov. 1991. 

DuPont in the U.S. developed about 1909, a smokeless powder from cotton of relatively low nitrogen that was quite soluble in ether alcohol. A small amount of diphenylamine was used as a stabilizer. After forming the grains and removing the liquid, a coating of graphite was added to make the smokeless powder that was used in the U.S. Other double-base types contain about 25% nitroglycerin. Cotton lint for nitration has been replaced by purified wood cellulose. 

Tensile Strength of Cast Double-Base Powder as a Function of Nitrocellulose Content P 423 Elongation of Cast Double-Base Powder as a Function of Nitrocellulose. Content. .. P 423 Modulus of Elasticity of Cast Double-Base Powder as a Function of 1 1 ... 

Marqueyrol s Stability Test. 200g samples of double-base powds were heated at 50° under vac in a round bottom Pyrex flask. Every 3—4 days, the vapors were pumped out, collected in, a gasometer over Hg and measured. The test was contd until the powd started to decomp very rapidiy, usually after 1800—2000 days. A curve was then plotted of cc of gas evolved vs days of heating, and the gas was analyzed for C02 and NO. If any liq formed, it was collected, measured and analyzed... 

If the proplnt is double-base, it has been observed that even the most stable propints bleach methyl violet paper in much shorter periods than one year. Investigations conducted by P.F. Macy at Picatinny Arsenal (Ref 4) showed that diphenylamine-stabilized doublebase proplnts in service storage at about 30°, may be considered of satisfactory stability if they do not cause complete bleaching of 0.1 N methyl violet paper in one month or less. Such proplnts always show satisfactory stability when subjected to the 65.5° Surveillance Test. It was observed at the same time, that double-base proplnts which had deteriorated, but were not yet hazardous, took from 11 to 24 days to bleach methyl violet paper at 30°... 

This applied particularly to double-base propints, although some single-base propints also gave erratic results. For these reasons, work was undertaken at Picatinny Arsenal to find an indicator that would be more reliable than methyl violet. About 60 commercially available dyes were examined by S. Helf (Ref 5) in exptl indicator paper tests, of which only three were found to be superior to methyl violet benzoazurine, trypan red and ethyl violet. Laboratory and surveillance testing showed that papers prepd with a 0.1% soln of benzoazurine did not change in color after one year when used with stable double-base propint, while methyl violet paper was bleached in nearly every case. The other two indicators mentioned above, trypan red and ethyl violet, were not as satisfactory as benzoazurine, although they were better than methyl violet. 

On the other hand, when paper strips with benzoazurine, trypan red or ethyl violet were exposed to unstable double-base propint, or to nitrogen oxide fumes prepd in the lab, all of the papers either bleached or faded, as did the methyl violet paper... 

Methyl Violet Paper Test for Double-Base Powders , PATR 1652 (1947) 5) S. Helf,... 

Development of an Indicator Test Paper for Detecting Stability of Double-Base Propellants , PATR 1782 (1950)... 

MJ Powder. An experimental double-base pro pint developed during WWII contg NC 48.0, NG 31.0, K nitrate 17.5, carbon blk 2.5 et centralite 1.0%... 

Cartridge Single Base Double Base Single Base Double Base Single Base Double Base... 

Neo (Poudres). Fr double-base proplnts containing diethyleneglycoldinitrate (DEGDN) and nitrocellulose... 

Some nitriles are expl, especially if they contain several —CN groups or a combination of —CN and —N02 groups. Other nitriles have been considered for use in double-base propints as they cool the flame and provide longer burning times a variety of alkyl nitriles have been investigated as plasticizers (Ref 7)... 

Kaufman et al, Nitriles as Plasticizers for Double Base Propellants , NDTS 1299 (NAVORD 4973) (1956) 8) D.N. Lapedes, Ed, Ency-... 

It is an expl with properties resembling those of Nitro-iso-butylglycol Di nitrate, and was proposed for use in Dynamites as either a substitute for, or in conjunction with NG, It may also be used in double-base propints Refs 1) Beil — not listed 2) F.H. Bergeim,... 

M.C, Philpot, Gas Chromatographic Determination of Plasticizers and Stabilizers in Composite Modified Double-Base Propellants , AnalChem 41 (1), 166-8 (1969) CA 70, 49143 (1969) 49) J. Trauchant, Chromato-... 

Lehalleur (Ref 2) states that Energit can be prepd by wetting small grains of double-base proplnt in a kneader with equal quantities of such volatile solvents as acet and furfural, adding liq aromatic nitrocompds and other ingredients, and then kneading the mixt until it is thoroughly blended. Finally, the solvents were removed by evapn (See also Ref 4, Ger 42-L)... 

The formulation for use in the Swedish Army rifle contained Guncotton 96.2, sol cotton 1.8, resin, a stabilizer and other materials 2.0%. These propints were very stable, nearly hygroscopic, and produced much lower temps than corresponding double-base powders such as Cordite, Ballis-tite, etc. As a result, gun barrel life was lengthened... 

NSDI and NS Dll. Span solventless (sin disol-vente) double-base propints intended for use in large cal guns... 

CA 31,5165 (1937) 4)P.Hayard, Vacuum Stability Tests on Solventless Double Base Powders Containing Various Stabilizers OSRD 5959 (20 Nov 1945), 28 Fig 32 5) J.G. Grasselli ed, Atlas of Spectral Data and Physical Constants for Organic Compounds ,... 

Richardson, Hazards Evaluation of the Cast Double-Base Manufacturing Process , ABL/X- 47 (1960), 45, AD 250858 25) F.A. Warren et... 

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