US3753348A - Propellant burning rate catalyst and method of propulsion - Google Patents

Propellant burning rate catalyst and method of propulsion Download PDF

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US3753348A
US3753348A US00850491A US3753348DA US3753348A US 3753348 A US3753348 A US 3753348A US 00850491 A US00850491 A US 00850491A US 3753348D A US3753348D A US 3753348DA US 3753348 A US3753348 A US 3753348A
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copper
burning rate
dichromate
propellant
rate catalyst
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C Burnside
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Phillips Petroleum Co
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    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
    • C06B23/007—Ballistic modifiers, burning rate catalysts, burning rate depressing agents, e.g. for gas generating
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
    • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
    • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin

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  • Padgett Attorney-Young & Quigg component and a minor amount of a suitable binder component comprised of a material selected from the groupconsisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from 4 to '10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from 4 to 10 carbon atoms per molecule with styrene asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by.
  • a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula Cu GU01 ⁇ N/ 4-2m wherein: R is selected from the group consisting of alkyl and alkenyl radicalscontaining from 1 to 4 carbon atoms; R is a pyridyl radical; in is the number of R' substituents and is an integer of from 0 to l; and n is the number of R substituents and is an integer of from 0 to 3.
  • Solid propellants can be classified with respect to composition as double base type, single base type, and composite type.
  • An example of a double base propellant is ballistite which comprises essentially nitroglycerine and nitrocellulose.
  • Examples of single base propellants are nitrocellulose and trinitrotoluene.
  • Composite type propellants are generally composed of an oxidizer, and a binder or fuel. They may contain other materials to improve fabrication or increase ballistic performance such as a burning rate catalyst.
  • Jet propulsion motors of the type in which the propellants of this invention are applicable can be employed to aid a heavily loaded plane in take off.
  • Said motors can also be employed as an auxiliary to the conventional power plant when an extra surge of power is required.
  • Said motors can also be employed to propel projectiles and land vehicles.
  • Said propellants can also be used for uses other than propulsion. For example, they can be used as gas generators in starting devices, power units where a fluid is employed as a motive force, and other applications where a comparatively large volume of gas is required in a relatively short period of time.
  • Solid propellants having relatively slow burning rates are entirely satisfactory for use in JATO units, i.e.,
  • rocket units employed as jet assist take off units which aid in powering loaded aircraft during take off.
  • propellants having relativelyslow burning rates are not entirely satisfactory for use where a propellant having a relatively high burning rate is required so that maximum thrust can be developed in minimum time as in booster rocket applications, or in said gas generator systems.
  • An object of this invention is to provide a new buming rate catalyst for solid propellants. Another object of this invention is to provide a burning rate catalyst comprising essentially certain complexes of a pyridine with copper and hexavalent chromium. Another object of this invention is to provide an improved propellant composition comprising a binder component, an oxidizer component, and said burning rate catalyst. Another object of this invention is to provide an improved gas generation system. Still another object of this invention is to provide an improved method of developing thrust which comprises burning said improved propellant in the combustion chamber of a rocket motor.
  • a burning rate catalyst for solid propellant compositions a complex of a pyridine containing copper and hexavalent chromium, selected from the group of compounds characterized by the formula wherein: R is selected from the group consisting of alkyl and alkenyl radicals containing from one to four carbon atoms; R is a pyridyl radical; m is the number of R substituents and can be one of O and 1; n is the number of R substituents and can be one of 0, l, 2 and 3; and the number of pyridine rings within the bracket is always 4, i.e., when m 0 there arev four pyridine rings as shown, and when m 1 there are two di-pyridyl groups.
  • each R is selected from the group consisting of a hydrogen atom and alkyl and alkenyl radicals containing from one to four carbon atoms, and at least two of said R substituents are hydrogen; and wherein: in formula II, each R" is selected from the group consisting of a hydrogenatom, a pyridyl radical, and alkyl and alkenyl radicals containing from one to four carbon atoms, one and only one of said R substituents is a pyridyl radical, and at least two of said R" substituents are hydrogen.
  • an improved solid propellant composition comprising a binder component, an oxidizer component, and a burning rate catalyst of the type described above.
  • an improved method of developing thrust which comprises burning the improved propellant of the invention in a combustion chamber of a rocket motor.
  • the amount of said burning rate catalyst is within the range of about 0.2 to about ll weight per cent of said total propellant composition-
  • base propellant is defined as binder plus oxidizer.
  • the presently preferred burning rate catalyst of the invention is tetrapyridine copper II dichromate.
  • This material was prepared as follows. Fifty grams of Cu- SO .5H O was dissolved in 300 grams of water. Pyridine was then added in excess to the resulting solution, with stirring, to form a complex with the cupric sulfate. An aqueous solution of potassium dichromate weight per cent) was then added at room temperature to the solution of copper sulfate-pyridine complex. A yellow-green, fine precipitate of tetrapyridine copper II dichromate immediately formed. Said precipitate was filtered off, washed with water, and air dried. This method of preparation can be used in preparing other burning rate catalysts of the invention, i.e., the hydrocarbon substituted and the pyridyl substituted derivatives of tetrapyridine copper ll dichromate.
  • the burning rate catalysts of the invention are particularly suitable for use in propellant compositions wherein the binder component comprises a rubbery material, e.g., a natural rubber or a synthetic rubber. Said burning rate catalysts impart an enhanced burning rate higher than obtained with catalysts of the prior art and do not injure the physical properties of the propellant.
  • Oxidizers which are applicable in the solid propellant compositions of this invention are those oxygencontaining solids which readily give up oxygen and include, for example, ammonium, alkali metal, and alkaline earth metal salts of nitric, perchloric, and chloric acids, and mixtures thereof.
  • Ammonium nitrate and ammonium perchlorate are the preferred oxidizers for use in the solid propellants of this invention.
  • Other specific oxidizers include sodium nitrate, potassium perchlorate, lithium chlorate, calcium nitrate, barium perchlorate, and strontium chlorate. Mixtures of oxidizers are also applicable.
  • the oxidizers are ground to a particle size, preferably within the range between 10 and 200 microns average particle size.
  • the amount of solid oxidizer used is usually a major amount of the total propellant composition and is generally in the range between 50 and 95 per cent by weight of the total propellant composition.
  • high energy additives include, among others, the following: boron, magnesium, aluminum, lithium, beryllium, various metal hydrides, etc.
  • the amount of said high energy additive will usually be within the range of 0 to 15 weight per cent of the total propellant compositron.
  • the total solids content i.e., solids such as inorganic oxidizing salt, finely divided high energy additive, burning rate catalyst, etc.
  • the binder content is increased accordingly.
  • a class of binder components widely used in solid propellant compositions and which form a presently preferred class of binders for use according to the invention comprises a rubbery copolymer of a conjugated diene and a heterocyclic nitrogen base.
  • These copolymers can vary in consistency from liquid polymers having a viscosity as low as 300 poises at 25 C., through very soft rubbers, i.e., materials which are soft at room temperature but will show retraction when relaxed, to those having a Mooney value (ML-4) up to 100.
  • the solid rubbery copolymers most frequently preferred have Mooney values in the range between 10 and 40.
  • the liquid copolymers most frequently preferred have viscosities within the range of 300 to 1,000 poises at 25 C.
  • Said copolymers can be prepared by any polymerization methods known to the art, e.g., mass or emulsion polymerization.
  • One convenient method for preparing these copolymers is by emulsion polymerization at temperatures in the range between 0 and F.
  • Recipes such as the iron pyrophosphatehydroperoxide, either sugar-free or containing sugar, the sulfoxylate, and the persulfate recipes are among those which are applicable. It is advantageous to polymerize to high conversion as the unreacted vinylpyridine monomer is difficult to remove by stripping.
  • the conjugated dienes employed are those containing from 4 to 10 carbon atoms per molecule and include 1,3-butadiene, isoprene, 2-methyl-l ,3-butadiene, and the like.
  • Various alkoxy, such as methoxy and ethoxy and cyano derivatives of these conjugated dienes, are also applicable.
  • other dienes such as phenylbutadiene, 2,3-dimethyl-l,3-hexadiene, 2-methoxy-3- ethylbutadiene, 2-ethoxy-3-ethyl-l,3-hexadiene, 2- cyano-1,3-butadiene, are also applicable.
  • a mixture of conjugated dienes can be employed.
  • a mixture of 1,3- butadiene and isoprene can be employed as the conjugated diene portion of the monomer system.
  • the polymerizable heterocyclic nitrogen bases which are applicable for the production of said polymeric materials are those of the pyridine, quinoline, and isoquinoline series which are copolymerizable with a conjugated diene and contain one, and only one,
  • substituent wherein- R is either hydrogen or a methyl group. That is, the substituent is either a vinyl or an alpha-methylvinyl (isopropenyl) group.
  • the compounds of the pyridine series are of the greatest interest commercially at present.
  • Various substituted derivatives are also applicable but the total number of carbon atoms in the groups attached to the carbon atoms of the heterocyclic nucleus should not be greater than because the polymerization rate decreases somewhat with increasing size of the alkyl group.
  • Compounds where the alkyl substituents are methyl and/or ethyl are available commercially.
  • R is selected from the group consisting of hydrogen, alkyl, vinyl, alpha-methylvinyl, alkoxy, halo, hydroxy, cyano, aryloxy, aryl, and combinations of these groups such as haloalkyl, alkylaryl, hydroxyaryl, and
  • carbon black in the copolymer during its preparation, this addition being accomplished by conventional methods, as for example, adding the carbon black to the latex prior to coagulation.
  • the amount of carbon black can be from zero to 35 parts of black per 100 parts of copolymer.
  • the amount of the conjugated diene will be at least 50 parts by weight per 100 parts of the monomer mixture, while the comonomer will be in the range of five to 50 parts.
  • polymerizable heterocyclic nitrogen bases are the preferred comonomers, other comonomers such as styrene are applicable.
  • any of the above-described copolymers can be employed in the practice of my invention.
  • many plastic, resinous, and other rubbery or flexible materials are suitable binder materials for the propellants of my invention.
  • the invention is not to be limited to any particular binder. Any suitable binder material can be employed.
  • able binders can be grouped as follows: asphalt and pitches including natural asphalts having a 170 F. softening point, air blown asphalts having a 270 F. softening point, mixtures of asphalt and synthetic or natural rubber, pitch having a 240 F.
  • epoxy resins such as Araldite 502 (an epoxy resin prepared by the condensation of epichlorohydrin with bisphenol A as described further in Kirk-Othmer, Encyclopedia of Chemical Technology, Volume X, page 809) and Epon 834 (a synethtic resin possessing terminal epoxide groups as described on page 72 in Zimmerman and Lavine, Supplement I (1956) to the 1953 edition of Handbook of Material Trade Names and in Kirk-Othmer Encyclopedia of Chemical Technology, Volume X, page 809) liquid polymers such as polybutadiene, polybutene, polyisobutylene, and Thiokol LP-3 (one of a series of liquid polysulfide polymers having a molecular weight of about 1,000 and a viscosity of about poises at 25 C.
  • Araldite 502 an epoxy resin prepared by the condensation of epichlorohydrin with bisphenol A as described further in Kirk-Othmer, Encyclopedia of Chemical Technology, Volume X, page 809
  • Epon 834 a synethtic resin possessing terminal e
  • the binder frequently will contain various conventional compounding ingredients such as reinforcing agents, plasticizers, wetting agents, anti-oxidants, etc.
  • Other ingredients which are employed for sulfur vulcanization include a vulcanization accelerator, a vulcanizing agent such as sulfur, and an accelerator activator, such as zinc oxide.
  • the binder comprises a copolymer comprising a conjugated diene and a polymerizable heterocyclic nitrogen base, it can also be cured by a quaternization reaction by incorporating therein a quaternizing agent and subjecting the resulting mixture to quaternizing conditions of temperature.
  • Suitable quaternizing agents include alkyl halides such as methyl iodide, methyl bromide; alkylene halides such as methylene iodide, ethylene bromide; substituted alkanes such as chloroform, brornoform, alkyl sulfates such as methyl sulfate; and various substituted aromatic compounds such as benzoyl chloride, methyl benzene sulfonate, and the like.
  • the quaternizing agent When liquid copolymers are used to form castable binders, the quaternizing agent must be polyfunctional.
  • quaternizing agents examples include: alpha, alpha-dichloro-pxylene; ricinoleyl di-alpha-chloroacetate plus Nacconate 3 l0 (3 ,3 -dimethyl-4,4'- dicyanatodiphenylmethane); and 1,5-dibromopentane.
  • the quaternizing temperature is usually in the range zero to C., although temperatures outside this range can be used.
  • binder is employed generically and includes various conventional compounding ingredients.
  • the binder content of the propellant composition will usually range from five to 50 per cent by weight.
  • the various ingredients in the propellant composition can be mixed on a roll mill or an internal mixer such as a Banbury or a Baker-Perkins dispersion blade mixer can be employed.
  • the binder forms a continuous phase in the propellant with the oxidant as the discontinuous phase.
  • One procedure for blending the propellant ingredients utilizes a stepwise addition of the solid ingredients such as oxidizer and burning rate catalyst to the binder.
  • the binder ingredients are mixed together to form a binder mixture and the oxidizer, burning rate catalyst, etc., are then added to said binder mixture in substantially equal subsequent additions.
  • Another suitable mixing procedure is that described in Example I below. Actually, any suitable mixing procedure can be employed and the mixing procedure can be varied depending upon whether the rocket grains are to be formed by compression molding, injection molding, extrusion, or casting techniques.
  • the curing temperature will be limited by the oxidizer employed in some cases but will generally be in the range between 70 and 250 F., preferably between 170 and 200 F.
  • the curing time must be long enough to give required creep resistance and other mechanical properties in the propellant. The time will generally range from around three hours when the higher curing temperatures are employed to seven days when curing is effected at lower temperatures.
  • the solids (ammonium perchlorate, aluminum powder, and tetrapyridine copper II dichromate) were blended together in a 35 cubic inch Z-blade mixer for a period of 1 minute.
  • the liquids (Bd/MVP, ZP-21l, HDMPCA, RCA, and Kel F Oil) were then added to said solids and blended for 15 minutes at 160 F.
  • Nacconate 310 (also a liquid) was then added to the resulting blend and mixing was continued, this time under vacuum, for an additional period of minutes at 160 F.
  • the final mixture was poured into strand molds, the molds were vibrated for 1 hour to remove entrained gases, and the resulting strands were cured for 48 hours at 160 F.
  • propellant B In preparing propellant B, the solids (ammonium perchlorate, aluminum powder, and tetrapyridine copper II dichromate) were blended together for 1 minute as in the preparation of propellant A.
  • the liquids Bd- MVP, ZP-2l l, and Kel F Oil
  • the alpha, alpha,- dichloro-para-xylene was then added to the blend and mixing continued, this time under vacuum, for 10 minutes at 160 F.
  • the final mixture was poured into strand molds, the molds were vibrated for 1 hour to remove entrained gases, and the resulting strands were then cured for 48 hours at 160 F.
  • propellant D In preparing propellant D, the catalyst tetrapyridine copper II dichromate was omitted. Otherwise, the method of preparation given above for propellant B was followed.
  • propellant E In preparing propellant E, a conventional catalyst, copper chromite, was employed instead of tetrapyridine cupric dichromate. Otherwise, the method of preparation given above for propellant A was followed.
  • the burning rate was obtained upon samples of the above-described propellant compositions A, B, C, D and E by burning strands of each in a Crawford bomb in the usual manner.
  • this method comprises restricting a strand of the propellant to be tested on all surfaces except one end so as to prevent burning except on said end. Said strand is then placed in a pressure bomb in a temperature bath maintained at a constant temperature (usually 70 F.), and the bomb is pressured to the desired pressure with nitrogen. Said strand is then ignited and the time required for the propellant to burn between two fusible wires spaced a known distance apart is recorded. The burning rate is then calculated in inches per second.
  • Table II The results of burning rate tests on the above-described propellant compositions are given in Table II below.
  • a comparison of the burning rates at 1000 psi for propellants A, C, and B shows that the tetrapyridine copper II dichromate catalyst of propellant A is a more effective catalyst than the copper chromite catalyst of propellant B.
  • An improved solid composite type propellant composition comprising: as a base propellant, a major amount of a solid'inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from four to 10 carbon atoms per'molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with styrene, asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about
  • a propellant composition according to claim 1 wherein said burning rate catalyst is di-(3-(3- pyridyl)pyridine) copper II dichromate.
  • a propellant composition according to claim 1 wherein said burning rate catalyst is di-(4-(4- pyridyl)pyridine) copper II dichromate.
  • a propellant charge comprising: as a base propellant, a major amount of a solid inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with styrene, asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybut
  • a method according to claim 10 wherein said burning rate catalyst is tetrapyridine copper II dichromate.
  • a method according to claim 10 wherein said burning rate catalyst is tetra-(2-methylpyridine) copper ll dichromate.
  • a method according to claim 10 wherein said burning rate catalyst is tetra-(2,6-dimethylpyridine) copper ll dichromate.
  • a method according to claim 10 wherein said burning rate catalyst is tetra-(3,4,6-trimethylpyridine) copper ll dichromate.
  • said burning rate catalyst is di(2-(2-pyridyl)pyridine) copper ll dichromate.
  • a method according to claim 10 wherein said burning rate catalyst is di(3-(3-pyridyl)pyridine) copper ll dichromate.
  • said burning rate catalyst is di-(4-(4-pyridyl)pyridine) copper ll dichromate.

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Abstract

1. An improved solid composite type propellant composition comprising: as a base propellant, a major amount of a solid inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from 4 to 10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from 4 to 10 carbon atoms per molecule with styrene asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by weight per 100 parts by weight of said base propellant of a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula

D R A W I N G

Description

urnsitle Y 7 Aug. 21, 1973 PROPELLANT BURNING RATE CATALYST AND METHOD OF PROPULSION Charles 11. Burns|de,'Waco, Tex.
{ 7}] Assigncc: Phllllps Petroleum Company,
' Burtlcsville, Okla.
[22 Filed; Nov. 2, 1959 i [21] Appl. No.: 850,491
[75] Inventor:
[52] US. Cl 60/219, 149/18, 149/19,
v149/20 [51] Int. Cl. .i C06d'5/06 [58] Field of Search 60/35, 4, 219;
[56] References Cited UNITED STATES PATENTS 2,555,333 6/1951 Grand etal 149/19 2,637,274 5/1953 Taylor et a1. 149/19 2,877,504 3/1959 Fox 149/19 2,904,420 9/1959 Halker 149/19 2,923,610 2/1960 Harper et a1 149/19 2,923,612 2/1960 Harrison 149/19 Primary Examiner-Benjamin R. Padgett Attorney-Young & Quigg component and a minor amount of a suitable binder component comprised of a material selected from the groupconsisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from 4 to '10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from 4 to 10 carbon atoms per molecule with styrene asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by. weight per 100 parts by weight of said base propellant of a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula Cu GU01 \N/ 4-2m wherein: R is selected from the group consisting of alkyl and alkenyl radicalscontaining from 1 to 4 carbon atoms; R is a pyridyl radical; in is the number of R' substituents and is an integer of from 0 to l; and n is the number of R substituents and is an integer of from 0 to 3.
18 Claims, No Drawings 1 PROPELLAN'I' BURNING RATE CATALYST AND METHOD OF PROPULSION burning rate having a new burning rate catalyst incorporated therein.
Solid propellants can be classified with respect to composition as double base type, single base type, and composite type. An example of a double base propellant is ballistite which comprises essentially nitroglycerine and nitrocellulose. Examples of single base propellants are nitrocellulose and trinitrotoluene. Composite type propellants are generally composed of an oxidizer, and a binder or fuel. They may contain other materials to improve fabrication or increase ballistic performance such as a burning rate catalyst.
Rocket propellants have achieved considerable commercial importance as well as military importance. Jet propulsion motors of the type in which the propellants of this invention are applicable can be employed to aid a heavily loaded plane in take off. Said motors can also be employed as an auxiliary to the conventional power plant when an extra surge of power is required. Said motors can also be employed to propel projectiles and land vehicles. Said propellants can also be used for uses other than propulsion. For example, they can be used as gas generators in starting devices, power units where a fluid is employed as a motive force, and other applications where a comparatively large volume of gas is required in a relatively short period of time.
Solid propellants having relatively slow burning rates are entirely satisfactory for use in JATO units, i.e.,
rocket units employed as jet assist take off units which aid in powering loaded aircraft during take off. However, many of said propellants having relativelyslow burning rates are not entirely satisfactory for use where a propellant having a relatively high burning rate is required so that maximum thrust can be developed in minimum time as in booster rocket applications, or in said gas generator systems.
I have discovered that certain complex compounds wherein a pyridine is complexed with copper and hexavalent chromium, defined further hereinafter, are effective in increasing the burning rate of solid propellants having relatively slow burning rates to the extent that said propellants can be used where propellants having high burning rates are required.
An object of this invention is to provide a new buming rate catalyst for solid propellants. Another object of this invention is to provide a burning rate catalyst comprising essentially certain complexes of a pyridine with copper and hexavalent chromium. Another object of this invention is to provide an improved propellant composition comprising a binder component, an oxidizer component, and said burning rate catalyst. Another object of this invention is to provide an improved gas generation system. Still another object of this invention is to provide an improved method of developing thrust which comprises burning said improved propellant in the combustion chamber of a rocket motor. Other aspects, objects and advantages of the invention will be apparent to those skilled in the art in view of this disclosure.
Thus according to the invention, there is provided as a burning rate catalyst for solid propellant compositions, a complex of a pyridine containing copper and hexavalent chromium, selected from the group of compounds characterized by the formula wherein: R is selected from the group consisting of alkyl and alkenyl radicals containing from one to four carbon atoms; R is a pyridyl radical; m is the number of R substituents and can be one of O and 1; n is the number of R substituents and can be one of 0, l, 2 and 3; and the number of pyridine rings within the bracket is always 4, i.e., when m 0 there arev four pyridine rings as shown, and when m 1 there are two di-pyridyl groups.
Instead of the single structural formula given above, the group of compounds forming the burning rate catalysts of the invention can be characterized by the following structural formulas R R I I R I! Cu Cl201 Cu CrzOz I II wherein: in formula I, each R is selected from the group consisting of a hydrogen atom and alkyl and alkenyl radicals containing from one to four carbon atoms, and at least two of said R substituents are hydrogen; and wherein: in formula II, each R" is selected from the group consisting of a hydrogenatom, a pyridyl radical, and alkyl and alkenyl radicals containing from one to four carbon atoms, one and only one of said R substituents is a pyridyl radical, and at least two of said R" substituents are hydrogen.
The compounds characterized by formula I are a presently preferred group due to their ease of preparation and availability.
Further according to the invention, there is provided an improved solid propellant composition comprising a binder component, an oxidizer component, and a burning rate catalyst of the type described above.
Still further according to the invention, there is provided an improved method of developing thrust which comprises burning the improved propellant of the invention in a combustion chamber of a rocket motor.
Examples of said complex compounds of pyridines which can be used in the practice of the invention include, among others, the following:
Tetrapyridine copper Il dichromate Tetra-( Z-methylpyridine) copper II dichromate Tetra-(2,6-dimethylpyridine) copper II dichromate Tetra-(2-alpha-methylvinylpyridine) copper II dichromate Tetra-( 2-methyl-5-vinylpyridine) copper II dichromate Tetra-(3-butenylpyridine) copper II dichromate Tetra-(3,4,6-trimethylpyridine) copper II dichromate Tetra-( 3-n-butylpyridine) copper II dichromate Tetra-( 2-n-propylpyridine) copper II dichromate Di-(2-( 2-pyridyl)pyridine) copper II dichromate Di-(3-(3-pyridyl)pyridine) copper II dichromate Di-(4-(4-pyridyl)pyridine) copper ll dichromate Di-(2-(2-pyridyl)-4-methylpyridine) copper Il dichromate Di-(2-(2pyridyl)-5-ethylpyridine) copper ll dichromate The amount of the burning rate catalysts employed in the propellant compositions of the invention is usually within the range of about 0.25 to about 12 parts by weight per 100 parts by weight of base propellant. When calculated on the basis of the total propellant composition, the amount of said burning rate catalyst is within the range of about 0.2 to about ll weight per cent of said total propellant composition- As used herein and in the claims, unless otherwise specified, the term base propellant" is defined as binder plus oxidizer.
The presently preferred burning rate catalyst of the invention is tetrapyridine copper II dichromate. This material was prepared as follows. Fifty grams of Cu- SO .5H O was dissolved in 300 grams of water. Pyridine was then added in excess to the resulting solution, with stirring, to form a complex with the cupric sulfate. An aqueous solution of potassium dichromate weight per cent) was then added at room temperature to the solution of copper sulfate-pyridine complex. A yellow-green, fine precipitate of tetrapyridine copper II dichromate immediately formed. Said precipitate was filtered off, washed with water, and air dried. This method of preparation can be used in preparing other burning rate catalysts of the invention, i.e., the hydrocarbon substituted and the pyridyl substituted derivatives of tetrapyridine copper ll dichromate.
The burning rate catalysts of the invention are particularly suitable for use in propellant compositions wherein the binder component comprises a rubbery material, e.g., a natural rubber or a synthetic rubber. Said burning rate catalysts impart an enhanced burning rate higher than obtained with catalysts of the prior art and do not injure the physical properties of the propellant.
Oxidizers which are applicable in the solid propellant compositions of this invention are those oxygencontaining solids which readily give up oxygen and include, for example, ammonium, alkali metal, and alkaline earth metal salts of nitric, perchloric, and chloric acids, and mixtures thereof. Ammonium nitrate and ammonium perchlorate are the preferred oxidizers for use in the solid propellants of this invention. Other specific oxidizers include sodium nitrate, potassium perchlorate, lithium chlorate, calcium nitrate, barium perchlorate, and strontium chlorate. Mixtures of oxidizers are also applicable. In the preparation of the solid rocket propellant compositions, the oxidizers are ground to a particle size, preferably within the range between 10 and 200 microns average particle size. The amount of solid oxidizer used is usually a major amount of the total propellant composition and is generally in the range between 50 and 95 per cent by weight of the total propellant composition.
It is also within the scope of the invention to include various finely divided high energy additives in the propellant compositions of the invention. Examples of said high energy additives include, among others, the following: boron, magnesium, aluminum, lithium, beryllium, various metal hydrides, etc. The amount of said high energy additive will usually be within the range of 0 to 15 weight per cent of the total propellant compositron.
When the propellant grains are to be prepared by casting techniques, using a liquid binder which is subsequently cured to a solid, the total solids content, i.e., solids such as inorganic oxidizing salt, finely divided high energy additive, burning rate catalyst, etc., should not exceed about weight per cent of the total propellant composition in order to obtain a flowable mixture which will properly fill the mold in which the propellant is cast. In such compositions, the binder content is increased accordingly.
A class of binder components widely used in solid propellant compositions and which form a presently preferred class of binders for use according to the invention comprises a rubbery copolymer of a conjugated diene and a heterocyclic nitrogen base. These copolymers can vary in consistency from liquid polymers having a viscosity as low as 300 poises at 25 C., through very soft rubbers, i.e., materials which are soft at room temperature but will show retraction when relaxed, to those having a Mooney value (ML-4) up to 100. The solid rubbery copolymers most frequently preferred have Mooney values in the range between 10 and 40. The liquid copolymers most frequently preferred have viscosities within the range of 300 to 1,000 poises at 25 C. Said copolymers can be prepared by any polymerization methods known to the art, e.g., mass or emulsion polymerization. One convenient method for preparing these copolymers is by emulsion polymerization at temperatures in the range between 0 and F. Recipes such as the iron pyrophosphatehydroperoxide, either sugar-free or containing sugar, the sulfoxylate, and the persulfate recipes are among those which are applicable. It is advantageous to polymerize to high conversion as the unreacted vinylpyridine monomer is difficult to remove by stripping.
The conjugated dienes employed are those containing from 4 to 10 carbon atoms per molecule and include 1,3-butadiene, isoprene, 2-methyl-l ,3-butadiene, and the like. Various alkoxy, such as methoxy and ethoxy and cyano derivatives of these conjugated dienes, are also applicable. Thus, other dienes, such as phenylbutadiene, 2,3-dimethyl-l,3-hexadiene, 2-methoxy-3- ethylbutadiene, 2-ethoxy-3-ethyl-l,3-hexadiene, 2- cyano-1,3-butadiene, are also applicable. Instead of using a single conjugated diene, a mixture of conjugated dienes can be employed. Thus, a mixture of 1,3- butadiene and isoprene can be employed as the conjugated diene portion of the monomer system.
The polymerizable heterocyclic nitrogen bases which are applicable for the production of said polymeric materials are those of the pyridine, quinoline, and isoquinoline series which are copolymerizable with a conjugated diene and contain one, and only one,
substituent wherein- R is either hydrogen or a methyl group. That is, the substituent is either a vinyl or an alpha-methylvinyl (isopropenyl) group. Of these, the compounds of the pyridine series are of the greatest interest commercially at present. Various substituted derivatives are also applicable but the total number of carbon atoms in the groups attached to the carbon atoms of the heterocyclic nucleus should not be greater than because the polymerization rate decreases somewhat with increasing size of the alkyl group. Compounds where the alkyl substituents are methyl and/or ethyl are available commercially.
These heterocyclic nitrogen bases have the formula where R is selected from the group consisting of hydrogen, alkyl, vinyl, alpha-methylvinyl, alkoxy, halo, hydroxy, cyano, aryloxy, aryl, and combinations of these groups such as haloalkyl, alkylaryl, hydroxyaryl, and
- the like; one and only one of said groups being selected alpha-methylvinyl)-8-dodecylquinoline; 3- vinylisoquinoline; l,G-dimethyl-3-vinylisoquinoline; 2-vinyl-4-benzylquinoline; 3-vinyl-5- chloroethylquinoline-3-vinyl5 ,-dichloroisoquinoline; 2-vinyl-6-ethoxy-7-methylquinoline; 3-vinyl-6- hydroxymethylisoquinoline; and the like.
It is often desirable to incorporate carbon black in the copolymer during its preparation, this addition being accomplished by conventional methods, as for example, adding the carbon black to the latex prior to coagulation. The amount of carbon black can be from zero to 35 parts of black per 100 parts of copolymer. In the preparation of the copolymers, the amount of the conjugated diene will be at least 50 parts by weight per 100 parts of the monomer mixture, while the comonomer will be in the range of five to 50 parts. Although, polymerizable heterocyclic nitrogen bases are the preferred comonomers, other comonomers such as styrene are applicable.
Any of the above-described copolymers can be employed in the practice of my invention. In addition, many plastic, resinous, and other rubbery or flexible materials are suitable binder materials for the propellants of my invention. Thus, the invention is not to be limited to any particular binder. Any suitable binder material can be employed. The binder material, per se, forms no part of the invention. Examples of other suit- 2-vinylquinoline,
able binders can be grouped as follows: asphalt and pitches including natural asphalts having a 170 F. softening point, air blown asphalts having a 270 F. softening point, mixtures of asphalt and synthetic or natural rubber, pitch having a 240 F. softening point, and mixtures of pitch and rubber; epoxy resins, such as Araldite 502 (an epoxy resin prepared by the condensation of epichlorohydrin with bisphenol A as described further in Kirk-Othmer, Encyclopedia of Chemical Technology, Volume X, page 809) and Epon 834 (a synethtic resin possessing terminal epoxide groups as described on page 72 in Zimmerman and Lavine, Supplement I (1956) to the 1953 edition of Handbook of Material Trade Names and in Kirk-Othmer Encyclopedia of Chemical Technology, Volume X, page 809) liquid polymers such as polybutadiene, polybutene, polyisobutylene, and Thiokol LP-3 (one of a series of liquid polysulfide polymers having a molecular weight of about 1,000 and a viscosity of about poises at 25 C. as described on page 241 of Supplementl (1956) to the 1953 edition of Handbook of Material Trade Names and in Kirk-Othmer Encyclopedia of Chemical Technology, Volume XI, page 842); polyethylenes, rubbers, both natural and synthetic, such as butyl rubber, ethyl acrylate-methylvinylpyridine copolymers, polybutadiene, and hydrogenated polybutadiene; waxes, both natural and synthetic having a melting point within the range of to 300 F.; synthetic resins and plastics such as the various acrylic and polyvinyl resins; and nitro polymers such as polynitromethylmethylacrylate, nitropolybutadiene and polynitrovinyl alcohols.
The binder frequently will contain various conventional compounding ingredients such as reinforcing agents, plasticizers, wetting agents, anti-oxidants, etc. Other ingredients which are employed for sulfur vulcanization include a vulcanization accelerator, a vulcanizing agent such as sulfur, and an accelerator activator, such as zinc oxide. When the binder comprises a copolymer comprising a conjugated diene and a polymerizable heterocyclic nitrogen base, it can also be cured by a quaternization reaction by incorporating therein a quaternizing agent and subjecting the resulting mixture to quaternizing conditions of temperature.
Suitable quaternizing agents include alkyl halides such as methyl iodide, methyl bromide; alkylene halides such as methylene iodide, ethylene bromide; substituted alkanes such as chloroform, brornoform, alkyl sulfates such as methyl sulfate; and various substituted aromatic compounds such as benzoyl chloride, methyl benzene sulfonate, and the like. When liquid copolymers are used to form castable binders, the quaternizing agent must be polyfunctional. Examples of such quaternizing agents are: alpha, alpha-dichloro-pxylene; ricinoleyl di-alpha-chloroacetate plus Nacconate 3 l0 (3 ,3 -dimethyl-4,4'- dicyanatodiphenylmethane); and 1,5-dibromopentane. The quaternizing temperature is usually in the range zero to C., although temperatures outside this range can be used. Thus, it will be understood that herein and in the claims, unless otherwise specified, the term binder is employed generically and includes various conventional compounding ingredients. The binder content of the propellant composition will usually range from five to 50 per cent by weight.
The various ingredients in the propellant composition can be mixed on a roll mill or an internal mixer such as a Banbury or a Baker-Perkins dispersion blade mixer can be employed. The binder forms a continuous phase in the propellant with the oxidant as the discontinuous phase. One procedure for blending the propellant ingredients utilizes a stepwise addition of the solid ingredients such as oxidizer and burning rate catalyst to the binder. The binder ingredients are mixed together to form a binder mixture and the oxidizer, burning rate catalyst, etc., are then added to said binder mixture in substantially equal subsequent additions. Another suitable mixing procedure is that described in Example I below. Actually, any suitable mixing procedure can be employed and the mixing procedure can be varied depending upon whether the rocket grains are to be formed by compression molding, injection molding, extrusion, or casting techniques.
After the grains are formed, they are cured. The curing temperature will be limited by the oxidizer employed in some cases but will generally be in the range between 70 and 250 F., preferably between 170 and 200 F. The curing time must be long enough to give required creep resistance and other mechanical properties in the propellant. The time will generally range from around three hours when the higher curing temperatures are employed to seven days when curing is effected at lower temperatures.
The following examples will serve to further illustrate the invention.
EXAMPLE Five propellants having the compositions given in Table I below were prepared.
In preparing propellant A, the solids (ammonium perchlorate, aluminum powder, and tetrapyridine copper II dichromate) were blended together in a 35 cubic inch Z-blade mixer for a period of 1 minute. The liquids (Bd/MVP, ZP-21l, HDMPCA, RCA, and Kel F Oil) were then added to said solids and blended for 15 minutes at 160 F. Nacconate 310 (also a liquid) was then added to the resulting blend and mixing was continued, this time under vacuum, for an additional period of minutes at 160 F. The final mixture was poured into strand molds, the molds were vibrated for 1 hour to remove entrained gases, and the resulting strands were cured for 48 hours at 160 F.
In preparing propellant B, the solids (ammonium perchlorate, aluminum powder, and tetrapyridine copper II dichromate) were blended together for 1 minute as in the preparation of propellant A. The liquids (Bd- MVP, ZP-2l l, and Kel F Oil) were then added to the blend of solids and the mixture blended for an additional minutes at 160 F. The alpha, alpha,- dichloro-para-xylene was then added to the blend and mixing continued, this time under vacuum, for 10 minutes at 160 F. The final mixture was poured into strand molds, the molds were vibrated for 1 hour to remove entrained gases, and the resulting strands were then cured for 48 hours at 160 F.
In preparing propellant C, the catalyst tetrapyridine copper II dichromate was omitted. Otherwise, the method of preparation given above for propellant A was followed.
In preparing propellant D, the catalyst tetrapyridine copper II dichromate was omitted. Otherwise, the method of preparation given above for propellant B was followed.
In preparing propellant E, a conventional catalyst, copper chromite, was employed instead of tetrapyridine cupric dichromate. Otherwise, the method of preparation given above for propellant A was followed.
5 TABLE I.COMPOSITION 0F PROPELLANTS Propellant, weight percent Ingredients A MMB- C l) E Liquid Bd/MVP (75/25) 13. 02 13.37 13. 02 13. 37 13. 02 10 ZP-Zll. 1. 96 4. 69 1. 96 4. 69 1. 06
HDMPCA 1.05 RCA 1. 57 Naceonate 310 1. 40 R211 polymer oil No.3 1.00 Ammonium perchlorate (18 micron particle size)....... 11. 70 11.70 1 00 12. 0U 11. TU Ammonium perchlorate (200 micron particle size) 54.110 5-1. (30 56. 00 56. ()0 54. 60 Aluminum powder (13 mircon). 11. 11.70 12.00 12. 00 11.70 Tetrapyridine cooper II (lichr0n1ate.... 7 J. 00 2. 00 Copper chromite. 2. on
Total 100. 00 100. 01) 100. 00 100. ()0 I00. [)0
The burning rate was obtained upon samples of the above-described propellant compositions A, B, C, D and E by burning strands of each in a Crawford bomb in the usual manner. Briefly, this method comprises restricting a strand of the propellant to be tested on all surfaces except one end so as to prevent burning except on said end. Said strand is then placed in a pressure bomb in a temperature bath maintained at a constant temperature (usually 70 F.), and the bomb is pressured to the desired pressure with nitrogen. Said strand is then ignited and the time required for the propellant to burn between two fusible wires spaced a known distance apart is recorded. The burning rate is then calculated in inches per second. The results of burning rate tests on the above-described propellant compositions are given in Table II below.
TABLE II Burning Rates of Propellants a From test results. b From plot of test results A comparison of the burning rates at 1,000 psi for propellants A and C shows that the tetrapyridine copper Il dichromate catalyst materially increased .the burning rate of propellant A over that of propellant B which contained no catalyst.
A comparison of the burning rates at 1000 psi for propellants B and D shows that the tetrapyridine copper II dichromate catalyst materially increased the burning rate of propellant B over that of propellant D which contained no catalyst.
A comparison of the burning rates at 1000 psi for propellants A, C, and B shows that the tetrapyridine copper II dichromate catalyst of propellant A is a more effective catalyst than the copper chromite catalyst of propellant B.
As will be evident to those skilled in the art, various modifications of the invention can be made, or followed, in the light of the above disclosure without departing from the spirit or scope of said invention.
I claim:
1. An improved solid composite type propellant composition comprising: as a base propellant, a major amount of a solid'inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from four to 10 carbon atoms per'molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with styrene, asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by weight per 100 parts by weight of said base propellant of a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula Crz01 n is the number of R substituents and is an integer of from 0 to 3.
2. A propellant composition according to claim 1 wherein said burning rate catalyst is tetrapyridine copper II dichromate.
3. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(2- methylpyridine) copper ll dichromate.
4. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(2,6- dimethylpyridine) copper ll dichromate.
5. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(Z-methyl-S- vinylpyridine) copper ll dichromate.
6. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(3,4,6- trimethylpyridine) copper II dichromate.
7. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(2-(2- 10 pyridyl)pyridine) copper II dichromate.
8. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(3-(3- pyridyl)pyridine) copper II dichromate.
9. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(4-(4- pyridyl)pyridine) copper II dichromate.
10. In the method of developing thrust wherein a solid propellant charge contained in a combustion chamber of a rocket motor is ignited and then burned with the evolution of combustion gases which are exhausted from said combustion chamber, the step which comprises burning in said combustion chamber a propellant charge comprising: as a base propellant, a major amount of a solid inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with styrene, asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by weight per parts by weight of said base propellant of a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula n OM07 of R substituents and is an integer of from 0 to 1; and n is the number of R substituents and is an integer of from 0 to 3.
11. A method according to claim 10 wherein said burning rate catalyst is tetrapyridine copper II dichromate.
12. A method according to claim 10 wherein said burning rate catalyst is tetra-(2-methylpyridine) copper ll dichromate.
13. A method according to claim 10 wherein said burning rate catalyst is tetra-(2,6-dimethylpyridine) copper ll dichromate.
14. A method according to claim 10 wherein said burning rate catalyst is tetra-(2-methyl-5- vinylpyridine) copper II dichromate. 7
15. A method according to claim 10 wherein said burning rate catalyst is tetra-(3,4,6-trimethylpyridine) copper ll dichromate.
16. A method according to claim 10 wherein said burning rate catalyst is di(2-(2-pyridyl)pyridine) copper ll dichromate.
- 17. A method according to claim 10 wherein said burning rate catalyst is di(3-(3-pyridyl)pyridine) copper ll dichromate.
18. A method according to claim 10 wherein said burning rate catalyst is di-(4-(4-pyridyl)pyridine) copper ll dichromate.

Claims (18)

1. AN IMPROVED SOLID COMPOSITE TYPE PROPELLANT COMPOSITION COMPRISING: AS A BASE PROPELLANT, A MAJOR AMOUNT OF A SOLID INORGANIC OXIDIZING SALT AS AN OXIDIZER COMPONENT AND A MINOR AMOUNT OF A SUITABLE BINDER COMPONENT COMPRISED OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER, SYNTHETIC RUBBER, COPOLYMERS OF A CONJUGATED DIENE CONTAINING FROM 4 TO 10 CARBON ATOMS PER MOLECULE WITH A POLYMERIZABLE HETEROCYCLIC NITROGEN BASE, COPOLYMERS OF A CONJUGATED DIENE CONTAINING FROM 4 TO 10 CARBON ATOMS PER MOLECULE WITH STRYRENE ASPHALT, PITCH, MIXTURES OF ASPHALT AND NATURAL RUBBER, MIXTURES OF ASPHALT AND SYNTHETIC RUBBER, MIXTURES OF PITCH AND NATURAL RUBBER, MIXTURES OF PITCH AND SYNTHETIC RUBBER, EPOXY RESINS, POLYBUTADIENE, POLYBUTENE, POLYISOBUTYLENE, HYDROGENATED POLYBUTADIENE, NATURAL WAXES, SYNTHETIC WAXES, POLYETHYLENES, POLYSULFIDE RUBBERS, ARCYLIC RESINS, POLYVINYL RESINS, AND NITRO POLYMERS; AND FROM ABOUT 0.25 TO ABOUT 12 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF SAID BASE PROPELLANT OF A BURNING RATE CATALYST CONSISTING ESSENTIALLY OF A COMPLEX OF A PYRIDINE CONTAINING COPPER AND HEXAVALENT CHROMIUM AND SELECTED FROM THE GROUP OF COMPOUNDS CHARACTERIZED BY THE FORMULA
2. A propellant composition according to claim 1 wherein said burning rate catalyst is tetrapyridine copper II dichromate.
3. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(2-methylpyridine) copper II dichromate.
4. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(2,6-dimethylpyridine) copper II dichromate.
5. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(2-methyl-5-vinylpyridine) copper II dichromate.
6. A propellant composition according to claim 1 wherein said burning rate catalyst is tetra-(3,4,6-trimethylpyridine) copper II dichromate.
7. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(2-(2-pyridyl)pyridine) copper II dichromate.
8. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(3-(3-pyridyl)pyridine) copper II dichromate.
9. A propellant composition according to claim 1 wherein said burning rate catalyst is di-(4-(4-pyridyl)pyridine) copPer II dichromate.
10. In the method of developing thrust wherein a solid propellant charge contained in a combustion chamber of a rocket motor is ignited and then burned with the evolution of combustion gases which are exhausted from said combustion chamber, the step which comprises burning in said combustion chamber a propellant charge comprising: as a base propellant, a major amount of a solid inorganic oxidizing salt as an oxidizer component and a minor amount of a suitable binder component comprised of a material selected from the group consisting of natural rubber, synthetic rubber, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with a polymerizable heterocyclic nitrogen base, copolymers of a conjugated diene containing from four to 10 carbon atoms per molecule with styrene, asphalt, pitch, mixtures of asphalt and natural rubber, mixtures of asphalt and synthetic rubber, mixtures of pitch and natural rubber, mixtures of pitch and synthetic rubber, epoxy resins, polybutadiene, polybutene, polyisobutylene, hydrogenated polybutadiene, natural waxes, synthetic waxes, polyethylenes, polysulfide rubbers, acrylic resins, polyvinyl resins, and nitro polymers; and from about 0.25 to about 12 parts by weight per 100 parts by weight of said base propellant of a burning rate catalyst consisting essentially of a complex of a pyridine containing copper and hexavalent chromium and selected from the group of compounds characterized by the formula
11. A method according to claim 10 wherein said burning rate catalyst is tetrapyridine copper II dichromate.
12. A method according to claim 10 wherein said burning rate catalyst is tetra-(2-methylpyridine) copper II dichromate.
13. A method according to claim 10 wherein said burning rate catalyst is tetra-(2,6-dimethylpyridine) copper II dichromate.
14. A method according to claim 10 wherein said burning rate catalyst is tetra-(2-methyl-5-vinylpyridine) copper II dichromate.
15. A method according to claim 10 wherein said burning rate catalyst is tetra-(3,4,6-trimethylpyridine) copper II dichromate.
16. A method according to claim 10 wherein said burning rate catalyst is di(2-(2-pyridyl)pyridine) copper II dichromate.
17. A method according to claim 10 wherein said burning rate catalyst is di(3-(3-pyridyl)pyridine) copper II dichromate.
18. A method according to claim 10 wherein said burning rate catalyst is di-(4-(4-pyridyl)pyridine) copper II dichromate.
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US4057441A (en) * 1976-03-29 1977-11-08 Thiokol Corporation Solid propellant with burning rate catalyst
US4391660A (en) * 1981-09-10 1983-07-05 The United States Of America As Represented By The Secretary Of The Air Force Copper containing ballistic additives
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US20040094250A1 (en) * 2002-11-14 2004-05-20 Estes-Cox Corporation Composite propellant compositions
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US10266458B2 (en) * 2014-04-09 2019-04-23 Aerojet Rocketdyne, Inc Propellant with extended storage life
CN110982228A (en) * 2019-11-28 2020-04-10 北方斯伦贝谢油田技术（西安）有限公司 Power source for oil field bridge plug seat sealing and preparation method thereof

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