US2973256A - Ammonium nitrate solid composite propellant composition - Google Patents

Description

grains may be subjected in storage.

AMfMONiUM NITRATE SOLID COMPOSITE PROPELLANT COMPOSITION Jack Linsk, Highland, Ind, assignor to Standard Oil "Company, Chicago, 11]., a corporation of Indiana No Drawing. Filed Nov. 8, 1955, Ser. No. 545,789

'12 Claims. (Ci. 52-.5)

This invention pertains to a gas-generating composition consisting essentially of ammonium nitrate as the primary gas-producing component of the composition, a combustible binder material and a combustion catalyst. More particularly, the invention relates to a composition in the form of a shaped grain suitable for use in rocketry by generating a gas from a mixture consisting essentially of ammonium nitrate, a combustion catalyst and a combustible binder. Such composition is useful for the propulsion of rockets, such as ground-to-ground missiles, ship-to-shore missiles, air-to-air missiles, and airto-ground missiles; for assist take-oft rockets in aircraft and for producing gas at high pressure.

Ammonium nitrate is widely used as a component of high explosives, particularly the so-called safe explo- 'sives. highly explosive it is extremely insensitive to ordinary heating and cannot be readily detonated by the local ap plication of heat or by a blasting cap and when ignited ammonium nitrate alone does not burn and has a tendency to go out. The use of ammonium nitrate for rockets is attractive because of the low cost and availability of ammonium nitrate, because of the relatively low flame temperature of the decomposition of the nitrate and because of the excess free oxygen available.

Certain physical characteristics of ammonium nitrate and grain material produced therefrom introduce pro Even though ammonium nitrate is considered as lems with respect to sturdiness of the grains and chemical stability under high and low temperatures to which the Thus ammonium nitrate exists in different crystalline forms, and the transition from one form to a different form involves a volume change of the ammonium nitrate. Volume changes which occur at about 90 F. and also at about 0 F. are particularly destructive to shaped propellant grains.

A solid propellant gas-producing grain for assist takeoff service and in rocket propulsion must meet a great many service requirements. Jet planes operate from the Arctic region to the Equator and thence to the Antarctic region with service temperatures over this sweep in the range from --70 F. to +140 F. Bases for aircraft, military and commercial, are situated over this entire range. Rockets, ATO units and gas-generators must be capable of being stored frequently for :months under these conditions, i.e. the grain must not change with respect to dimensional configuration or develop fissures or cracks.

There should be no operation problems with the ignition of the grains under this wide range of atmospheric temperature; and the rate at which the gases are generated from the gas-generating composition must be substantially constant regardless of temperature.

The gas-producing grain must be physically strong. It must be able to withstand the handling in going from the point of manufacture thousands of miles by train, truck, ship, or aircraft to its final destination. Not only must it withstand rough treatment in its shipping case, but it 2,973,255 Patented Feb. 28,

must be capable of withstanding rough handling by nance people.

An object of this invention is a gas-generating composition using ammonium nitrate as a principal gasgenerati-ng material. Another object of this invention is a gas-generating composition which is ballistically stable after being subjected to high and low temperature environment. Still another object of the invention is a gasgenerating composition which is relatively stable chemically at temperatures encountered in storage. A further object of the invention is a gas-generating propellant composition which is capable of being shaped into combustible grains, which grains exhibit good ballistic performance following storage at high temperature and following mechanical shock in the handling of said grains. Other objects will be apparent in the detailed description of the invention.

The composition of this invention consists, on a weight basis of:

(1) About 15% to about 25% of a binder which consists essentially of, on a weight basis, of

(a) About 20% to about 40% of cellulose acetate polymeric material containing from about 51 to about 57% acetic acid, I

(b) About 10% to about 30% of dinitrotoluene, (0) About 10% to about 30% of a component selected from the class consisting of dinitrophenoxyethanol and mixtures of dinitrophenoxyethanol with bis(dinitrophenoxy)ethane which mixtures contain at least 50% by weight of dinitrophenoxyethanol,

(.d) About 25% to about 40% of ethylene glycol diglycolate, and (2) A combustion catalyst in an amount suflicient to promote combustion of said composition, and

(3) The remainder essentially ammonium nitrate. There may be included in the above composition from about 0.3 to about 2% by weight of finely divided carbon; from about 0.2 to 2% of an organic amine and a minor amount, e.g. of about 0.1%, of a surfactant. I

The binder of the composition consists essentially of cellulose acetate polymer plasticized with oxidizable plasticizer components which are described hereiubelow. The amount of binder in the composition may vary, on

ord-

a weight basis, from about 15% to about 25%, variation within this range being made to obtain well compacted and sturdy grains that do not deform under the conditions of storage and handling described above. The amount of binder in the composition is preferably adjusted to obtain stoichiornetric balance with respect to oxygen content of the composition in order to produce a relatively smoke-free gas. 1 g

The cellulose acetate component of the binder is a partially esterified cellulose acetate having an acetic acid content between about 51 and 57% by weight. A particularly suitable cellulose acetate is the commercial lacquer grade marketed as having an acetic acid content of 54 to 56% by weight; usually spoken of as containing about 55% acetic acid. (The term percent by weight acetic acid denotes the amount of acetic acid obtained on saponification of the cellulose acetate.) The binder contains on a weight basis between about 20% and about 40% of cellulose acetate polymer.

The dinitrotoluene component may be any one-ora mixture of the dinitrotoluenes having the two nitro groups attached to any two of the positions of the phenyl-nucleus. The 2,4-dinitrotoluene isomer is preferred. From about 10% to about 30% of dinitrotoluene is present in the binder. v

The binder also contains dinitrophenoxyethanol, in relatively pure form, or a mixture of dinitrophenoxyeth- .anol with bis(dinitrophenoxy)ethane which mixture conaa'raase tains at least 50% of dinitrophenoxyethanol and preferably at least about 60% by Weight of the dinitrophenox ethanol.

The dinitrophenoxyethanol may be any one ofthe various isomeric species, but is preferably the 2,4-dinitrophenoxyethanol. The mixture is most easily obtained as the product in the common methods of dinitrophenoxyethanol production. By control of the reaction conditions utilized in these prior art methods, the reaction product may contain as little as 10 weight percent of the bis(dinitrophenoxy)ethane (secondary reaction product) to as much as about 50 weight percent. The total reaction product may require purification When it contains, as produced, more than this amount of a econdary reaction product.

Suitable mixtures may be readily prepared by the method taught by Blanksma and Fohr, Rec. trav. chim. 65, 711 (1946), wherein dinitrochlorobenzene is reacted with ethylene glycol utilizing sodium as the condensing agent; or by the method of Fairbourne and Toms, J. Chem. Soc. 119, 2077 (1921), wherein caustic soda is used as the condensing agent. To illustrate: the preferred plasticizer mixture is prepared by reacting 3.5 mols of ethylene glycol with 1 mol of 2,4-dinitrochlorobenzene at a temperature in the range of about 80 to 95 C. for a contact time of about 4 hours, in the presence of 50% aqueous sodium hydroxide solution; about 1 part by weight of sodium hydroxide is used for each 5 parts of the dinitrochlorobenzene. The solid reaction product is removed from the liquid by filtration, water washed and dried at moderate temperature. Under these conditions the reaction product consists of about 63 weight percent of the primary reaction product, 2,4-dinitrophenoxyethanol, and about 37 weight'percent of the secondary reaction product, bis(2,4-dinitrophenoxy)ethane.

Several methods of analysis are available and it has been found that the composition of the'reaction product varies somewhat according to the analytical technique. For example, when utilizing ditferential solubility procedure the amount of the secondary reaction product is always greater than that found by direct analysis to determine the amount of 2,4-dinitrophenoxyethanol by acetylation, that is, by determination of the hydroxylnumber of the mixture. 1 If the mol ratio of ethylene glycol to 2,4-dinitrochlorobenzene is increased to about to 1 the amount of bis(2,4-dinitrophenoxy)ethane is reduced to about 10% by Weight of the reaction product. The primary reaction product, dinitrophenoxyethanol, can be separated by difierential solubility utilizing a boiling mixture of toluene or benzene to contact the reaction product. Relatively pure dinitrophenoxyethanol is recovered from the aromatic solvent by concentrating the solution and 4 definite melting point but liquifies over the temperature range of about 105 C. to 206 C.

The amount of the dinitrophenoxyethanol-containing component in the binder may vary within the range of from about 10% to about 30% by weight of the binder. The amount of this material included in the binder will vary Within this range depending upon the amount of other plasticizer components in the binder and on the relative amounts of dinitrophenoxyethanol and bis(dinitrophenoxy) ethane in the mixtures.

Usually the dinitrophenoxyethanol-containing component plus the dinitrotoluene component constitutesabout 40% by weight of the binder. When the mixture contains about 63% of 2,4-dinitrophenoxyethanol and about 37% of bis(2,4-dinitrophenoxy)ethane, the binder preferably contains about 20% of the mixture. When using 2,4-dinitrotoluene, the binder preferably contains about 20% thereof.

Ethylene glycol diglycolate is a component of the binder. This material is a polyester condensation reaction product having a molecular weight within the range of about 250 and about 1000. A molecular weight within the range of about 250 to about 600 is preferred. These low molecular Weights are obtained by using a mol excess of glycol to acid. The mol ratio of glycol to acid should bebetween about 1.02 and 1.3, preferably not less than about 1.15 to obtain the most satisfactory condensation product with respect to plasticizer properties. This material is described at length in the copending application of Norman]. Bowman and Wayne A. Proe ll, entitled Polyester Plasticizer, filed November 30, 1954, Serial No. 471,992, now abandoned.

The binder contains from about 25% to about 40% by weight of the ethylene glycol diglycolate, preferably about 30%.

' The combustion catalyst of this invention may be either an inorganic combustion catalyst or an organic catlayst. Examples of the inorganic catalyst suitable for promoting the combustion of the propellant grains are the Prussian blues, that is, the insoluble Prussian blue or soluble Prussian blue, or chromates and dichromatessuch as ammonium dichromate, sodium chromate or. sodium dichromate. Mixtures of Prussian blues and ammonium dichromate are particularly suitable for some uses. The preferred Prussian blue catalyst is insoluble Prussian blue. The monoalkali metal salts of barbituric acid such as V monosodium barbiturate are suitable organic catalysts.

fractionally crystallizing the dinitrophenoxyethanol' from I this solution. It is understood that considerable variation in the relative proportions of the primary and secondary reaction products produced in the product mixture may occur as a result of difierent methods of producing the dinitrophenoxyethanol-containing product and as a result of difference in operating conditions such as washing the product, ratio of intermediates in the reaction mixture, temperature, etc. For example, in producing the 2,4-dimtro species, variation in product washing technique with respect to amount of water and temperature of the water used for washing the product mixture may cause the relative amounts of primary and secondary reaction product to vary from about 60-65 parts by weight of primary reaction product to about 40-35 parts by weight of the secondaryreaction product when using a 3.5 .to 1 ratio of The primary reaction product, 2,4-dinit'rophenoxyethanol, melts at about 110 C. l The bis(2,4-dinitrophenoxy)- ethane melts at about 206 C. The mixture exhibits no The amount of catalyst used in the composition is between about l% to about 10% based on the weight of the grain. Preferably the amount is within the range of from about 2% to about 6%.

When mixtures 'of- Prussian blue and ammonium dichromate are used the proportion by weight of the Prussian blue and ammonium dichromate is in the range of about 0.5 to 2 parts by weightof Prussian blue per part by weight of ammonium dischomate.

The ammonium nitrate of this invention, which is the major component of the composition and which constitutes the remainder of the composition, may be ordinary commercial grade ammonium nitrate such as conventionally grained ammonium nitrate containing a small amount of impurities. It may be coated with a small amount of moisture-resisting material such as petroleum or paraffin. Military grade ammonium nitrate and Cl. grades uncoated are preferred. A mixture of finely ground and coarsely'ground ammonium nitrate is preferred, the major portion of the nitrate being finely ground.

asraesa either from the channel blacks or the furnace blacks may be used. A second type of carbon which is adaptable for use as a combustion promoter component is finely divided petroleum coke obtained in the pipe-stilling of midcontinent heavy residuums. Such coke usually contains less than 1% ash and hence, like the carbon blacks, is particularly suitable in gas-producing compositions where it is desired to keep to a minimum solid inorganic particles in the combustion gas. The coke is preferably ground to pass through a #325 US. standard sieve before use. The amount of carbon which may be used in the composition is within the range of 0.3 to 2% by weight of the composition.

Ammonium nitrate solid propellants may require an inhibitor component to reduce the gassing tendency of the composition under high temperature storage conditions when using some catalysts or large amounts of any catalyst. This gassing tendency may be avoided by the inclusion of aromatic amines in the composition. Examples of aromatic amines which are particularly efifective are the diaminotoluenes, diphenylamine, 1,3-diaminobenzene, diamino naphthylenes, dinaphthyl amine, phenylnaphthyl amine and the triaminotoluenes. Particularly suitable are diphenyl amine and 2,4-diaminotoluene'. The amine may be added in an amount within the range of from about 0.5 to about 2% of the weight of the composition. The amount is determined by the gassing tendency of the composition in the absence of amine.

A minor amount of a surfactant may be added to the composition to obtain improved contact of the components in mixing operations and in molding of the compositions to shaped grains. A suitable surfactant is sorbitan sesquioleate. The amount of surfactant is usually not more than about 0.1% by weight of the composition. The gas-forming compositions of this invention may be prepared by: (1) making the binder, (2) mixing binder with ammonium nitrate and other ingredients to form a homogeneous solid composition, (3) and molding the finished solid propellant grain. The binder is prepared by mixing heated cellulose acetate polymeric material with the plasticizer components in a suitable vessel. Mixing is continued until the mixture is completely plasticized. Blending of the binder with ammonium nitrate and the other components of the formulation may be carried out in the same mixer if desired. A mixing temperature of 90lO5 C. affords a homogeneous somewhat dough-like solid. Mixing may be carried out under reduced pressure in order to remove adsorbed surface moisture present in the materials.

In another method of preparing the propellant corn- F position the binder material is not prepared separately. In this method the dry components are first intimately mixed and the plasticizer is then added to the admixed dry components. The ammonium nitrate and cellulose acetate are subjected to a temperature of about 110120 C. under about /3 atmosphere pressure for a period of 30 to 60 minutes and the other dry materials, such as solid binder components, catalyst, etc. are intimately mixed with the nitrate and acetate for an additional 15 to 30 minutes under vacuum. The ethylene glycol diglycolate plasticizer is then added along with surfactant, if any, and the final mixture is prepared by mixing for a period of 60 to 180 minutes to obtain a homogeneous plasticized product, this final mixing being carried out at about 105-1 15 C.

Burning rate test strips of the gas-forming composition are prepared by extruding or molding at a temperature below about 120 C. under a pressure of about 2000 p.s.i. The strands are'coated with lacquer grade cellulose acetate on the sides to give strands which burn like a cigarette and these are burned in a pressure bomb under nitrogen pressure. Four to six strands about Mr" x A" x 5" in length'are burned at varying pressures between 600 and 1800 p.s.i. Plotting burning rate in inches per second against pressure on log-log paper KI: gives a straight line. The slope of this straight line is defined as the exponent of the burning rate related to pressure in the formula where B is the linear burning rate at pressure p, p is the linear burning rate for the composition at 1000 p.s.i., p is pressure in p.s.i. in the burning chamber and n is the pressure exponent showing dependence of the burning rate on pressure. This relationship of burning rate and pressure is discussed by R. N. Wimpress in Internal Ballistics of Solid Fuel Rockets (1950). A pressure exponent less than about 0.8 and preferably less than about 0.7 is desirable for the ammonium nitrate propellant composition.

Gas-producing grains are prepared from the above compositions containing ammonium nitrate, combustion promoter and binder material by molding under a pressure of about 2000 to 4000 p.s.i. The size and shape of the grains are dependent upon their intended use. Grains are provided with centrally located holes of different shapes, that is, starform, cruciform or circular. The gas-producing grains may be molded into disc-form, stacks of discs being used as gas-forming propellant ma terial for missile rockets.

The ends and cylindrical surface of the grains may be restricted with respect to burning area by a coating of a material such as cellulose acetate or asphalt to limit burning to particular surfaces. 7

The test data obtained by burning the grains in the test motor indicate overall performance of the compositions when used in assist take-off operations. For these operations the grains are mounted in a conventional case provided'with a suitably placed igniter charge such as cannon powder, which is fired electrically. The temperature of the gases produced by burning of grains may be of the order of 1500 F. to 3400 F. but usually below about 2500 F. and the pressure or impulse produced by the hot gases will be dependent upon the grain size, diameter of the nozzle, and other factors. 7

The grains are given a thermal shock test which is referred to as the cycling test. In this test, grains of a given composition are held in an oven at a temperature of 170 F. for a period of two hours, following which they are immediately subjected for a period of two hours to a temperature of -75 F. in a refrigerator to complete one cycle. After a second cycle, the grains are permitted to come to room temperature, i.e., about 75 to F. These grains are examined for indications of cracking, crystallinity, and resistance to deformation and shattering when dropped on a concrete surface. Grains are then fired at 75 F., F. and normal ambient temperatures following the cycling treatment. Grains, the binder of which consists of the plasticized cellulose acetate andplasticizer containing the'ethylene glycol diglycolate, dinitrotoluene and 2,4-dinitrophenoxyethanol-containing component of this invention show no physical defects following the thermal cycling test, and show firing qualities which are not affected by the cycling test. In another test the grains are dropped several feet to a concrete surface to test their mechanical strength. I

Another test to which finished grains are subjected is that of hot aging. In this test, grains are stored in an oven at 170 F. in the presence of circulating air. Several grains of a given composition are used in such a test. Grains are withdrawn periodically and fired in a test motor. The best grains will not be affected after 30 days or more of high temperature storage. A grain which will not tolerate prolonged hot storage malperforms ballistically. It may give an erratic time-pressure curve and may sometimes even burn with explosive violence. a

I 7 Example 1 A nitrophenoxyethanol binder component was pro test.

pared as follows. To a 70 gallon'stainless'steel kettle equipped with motor operated stirrer and heating coils, was added 109 pounds of ethylene glycol and 102 pounds of technical grade 2,4-dinitrochlorcbenzene to give a mol ratio of 3.5 to 1, ethylene glycol to the dinitrochlorobenzene. The stirred mixture was heated to 65 C. and a 50% aqueous solution of sodium hydroxide containing 22.7 pounds of caustic soda was added incrementally over a period of two hours. The heat of reaction was sufiicient to maintain the temperature at 8095 C. without external heating. Following addition of the caustic solution the mixture was stirred and the temperature was held at 8595 C. for an additional two hours after which thirty gallons of water was added slowly. The precipitated solid was filtered and the precipitate was resuspended and washed in forty gallons of water, at a temperature of 60 70 C. and filtered hot. The filter cake was washed repeatedly with gallon portions of warm water. Traces of sodium dinitrophenoxide resulting from partial hydrolysis of dinitrochlorobenzene were removed during the washing operation. The product was air-dried 10 days at ambient temperature. The yield of air-dried product containing less than 1% moisture was 72.5 pounds of crude product. This crude product consisted essentially of about 63 parts by weight of 2,4-dinitrophenoxyethanol and 37 parts by weight of bis(2,4-dinitrophenoxy ethane.

A mixture containing 32.5 parts by weight of lacquer grade cellulose acetate having an acetic acid content of about 55 weight percent; 14.8 parts by weight of commer cial grade 2,4-dinitrotoluene; 26.6 parts by weight of 2,4 dinitrophenoxyethanol product containing about 63% by weight of the 2,4-dinitrophenoxyethanol and about 37% by weight of bis(2,4-dinitrophenoxy)ethane; and 26.1 parts by weight of ethylene glycol diglycolate was heated at a temperature in the range of l110 C. and mixed about one hour to obtain a homogeneous plasticized binder material which was tough and flexible and showed good tear strength. To a portion of this binder material was added diphenyl amine and a mixture of insoluble Prussian blue and ammonium dichrornate catalyst containing these catalyst components in equal amounts. Carbon black, finely ground ammonium nitrate and a small amount of sorbitan sesquioleate were added and mixing was continued to obtain a homogeneous gas-forming V propellant formulation which contained the'following components.

Ammonium nitrate Grains in the form of 2.75" cylinders 4" long and having a starform centrally located hole were prepared by molding the above composition at 2400 psi. for 12 minutes. One of these grains was cycled in the thermal cycle test by subjecting it alternately to temperatures of 170 F. and 75 F. in two cycles as described hereinabove. Such cycling did not impair the physical structure of the grain which gave normal firing properties following'the Another. 4" star grain gave satisfactory firing performance in a rocket motor the gas produced being substantially smoke-free. Still another 4" grain was dropped 6 feet to a concrete floor and resisted fracture until the fourth drop from the 6. foot height. A burning strand prepared from the above composition showed a' burning 3 rate at 1000 psi; of0.118 inch per second and a pressure exponent of 0.58. 7

Example 2 A second composition'containing the same components as the composition of Example 1, but in dilferent proportions, was prepared according to the method described in tar grains of the same dimensions as grains of Example .1 were molded at'2700 p.s.i. from the composition of Example 2. Satisfactory rocket motor firings were obtained with these grains after being stored for 12, 20 and 31 days at 170 F. in the hot aging test. The gas produced upon firing these grains was substantially smoke-free. Additional like grains prepared from this composition were cycled successfully through the +170 No malformation of the F. and -75 F. cycle test. grains, external or internal, was produced in the grains in this severe cycle test. Strands of the composition btu'ned in a nitrogen atmosphere in a pressure bomb at a rate of 0.134" per second at 1000 p.s.i. The pressure exponent of the burning rate was 0.55.

Thus having described the invention what is claimed 1. A composition suitable for use as a solid propellant, which. composition consists essentially of, on a weight basis (1) from about 15% to about of binder material, which binder material consists, on a weight basis (a) about 20 to about 40% of celluiose acetate containing from about 51% to about 57% of acetic acid, (b) about 10% to about of dinitrotoluene, (c) about 25% to'about of ethylene glycol diglycolate.

and (d) about 10% to about 30% of a member selected a from the class consisting of dinitropheno-xyethancl and mixtures of dinitrophenoxyethanol and bis(dinitrophenoxy)ethane, which mixtures contain at least 50 weight percent dinitrophenoxyethanol, (2) a catalyst from the I (2,4-dinitrophenoxy)ethane.

is 2,4-dinitrophenoxyethanol. r

class consisting ofPrussion blue, ammonium dichromate, sodium chromate, sodium dichromate and monosodium barbiturate, in'an amount between about 1 and l0percent by weight; and (3) the remainder essentially ammonium nitrate.

2. The composition of claim 1 wherein said cellulose acetate contains about 55 weight percent of acetic acid. 3. The composition of claim 1 wherein said member is a mixture of about 63 parts by weightof 2,4-dinitrophenoxyethanol and about 37 parts by weight of bis- 4. The composition or" claim 1 wherein said member 5. The composition of claim 1 wherein said catalyst is present in an amount between about 1%. and about 10%. 6. The composition of claim 1 wherein said catalyst is Prussian blue,

7. The compoistion of claim 1' wherein said catalyst is ammonium dichrornate. V I g I 8. T-he composition of claim l whereingsaid catalyst is sodium barbiturate.

9. The eomposition ofjclaim l wherein said catalyst is a mixture of Prussion blue and ammonium dichromate in the proportion by weight of about 0.5 to 2.

10. The composition of claim 1 containing from about 0.3% to about 2% of finely divided carbon.

11. The composition of claim 1 containing from about 0.5% to about 2% of diphenylamine.

12. A gas-producing composition consisting essentially, on a Weight basis, of 1) from about 15 to about 25% of a binder said binder consisting of (a) about 30% cellulose acetate material having an acetic acid content of 10 about 55 weight percent, (b) about 30% ethylene glycol diglycolate, (0) about 20% 2,4-dinitrotoluene, and (d) about 20% of a mixture consisting of about 63% by weight 2,4-dinitrophenoxyethanol and about 37% by weight of bis(2,4-dinitrophenoxy)ethane; (2) from about 15 References Cited in the file of this patent UNITED STATES PATENTS 2,643,611 Ball June 30, 1953 FOREIGN PATENTS 655,585 Great Britain July 21, 1951

Claims (1)

1. A COMPOSITION SUITABLE FOR USE AS A SOLID PROPELLANT, WHICH COMPOSITION CONSISTS ESSENTIALLY OF, ON A WEIGHT BASIS (1) FROM ABOUT 15% TO ABOUT 25% OF BINDER MATERIAL, WHICH BINDER MATERIAL CONSISTS, ON A WEIGHT BASIS OF (A) ABOUT 20 TO ABOUT 40% OF CELLULOSE ACETATE CONTAINING FROM ABOUT 51% TO ABOUT 57% OF ACETIC ACID, (B) ABOUT 10% TO ABOUT 30% OF DINITROTOLUENE, (C) ABOUT 25% TO ABOUT 40% OF ETHYLENE GLYCOL DIGLYCOLATE, AND (D) ABOUT 10% TO ABOUT 30% OF A MEMBER SELECTED FROM THE CLASS CONSISTING OF DINITROPHENOXYETHANOL AND MIXTURES OF DINITROPHENOXYETHANOL AND BIS(DINITROPHENOXY)ETHANE, WHICH MIXTURES CONTAIN AT LEAST 50 WEIGHT PERCENT DINITROPHENOXYETHANOL, (2) A CATALYST FROM THE CLASS CONSISTING OF PRUSSION BLUE, AMMONIUM DICHROMATE, SODIUM CHROMATE, SODIUM DICHROMATE AND MONOSODIUM BARBITURATE, IN AN AMOUNT BETWEEN ABOUT 1 AND 10 PERCENT BY WEIGHT, AND (3) THE REMAINDER ESSENTIALLY AMMONIUM NITRATE.