EP1721881A1 - Propergol gélifié par polymère et son procédé de fabrication - Google Patents

Propergol gélifié par polymère et son procédé de fabrication Download PDF

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Publication number
EP1721881A1
EP1721881A1 EP06252111A EP06252111A EP1721881A1 EP 1721881 A1 EP1721881 A1 EP 1721881A1 EP 06252111 A EP06252111 A EP 06252111A EP 06252111 A EP06252111 A EP 06252111A EP 1721881 A1 EP1721881 A1 EP 1721881A1
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EP
European Patent Office
Prior art keywords
propellant
gelled
nanogellant
monomer
solvent
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP06252111A
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German (de)
English (en)
Inventor
Thomas A. Crofoot
John A. Starkovich
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Northrop Grumman Corp
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Northrop Grumman Corp
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Publication date
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Publication of EP1721881A1 publication Critical patent/EP1721881A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
    • 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
    • C06B23/001—Fillers, gelling and thickening agents (e.g. fibres), absorbents for nitroglycerine

Definitions

  • This invention relates generally to rocket propellants and, more particularly, to gelled propellants. It is well known in the field of rocket propulsion that gelled propellants offer significant advantages over solid and liquid propellants. Solid propellants have inherently high energy but offer no mission flexibility because once ignited they must normally be burned to completion. Liquid propellants are less energetic than solids, as measured by specific impulse, but offer high mission flexibility because the flow of liquid fuels can be controlled as desired. Gels combine the advantages of solids and liquids and have additional advantages that are well known to designers of rocket engines for use both in space and within a planet's atmosphere.
  • gelled propellants available prior to this invention have been produced by mixing essentially inert solids with liquids.
  • a commonly used gellant is silicon dioxide.
  • US Patent No. 6,165,293 entitled “Thixotropic IRFNA Gel,” discloses a gelled monomethyl hydrazine (MMH) fuel in which cellulose is the principal gallant and aluminum is added to increase energy density, and a gelled oxidizer in which the gellant is silicon dioxide and lithium niobate.
  • MMH monomethyl hydrazine
  • oxidizer gellant is either silicon dioxide, an unspecified metallic oxide, or an unspecified swellable polymer.
  • Polymers that are typically considered as gellants for propellants are cellulose or cellulose derivatives.
  • the present invention resides in the use of a polymeric gellant that satisfies the physical requirements for a gelled propellant, but also adds energy content to the propellant.
  • the invention may be defined as a gelled propellant, comprising a polymeric nanogellant formed from a monomer having molecular properties that promote three-dimensional polymerization; and a propellant to which the polymeric nanogellant is added.
  • the resulting gelled propellant has desirable rheological properties and the polymeric nanogellant adds energy content to the propellant.
  • the polymeric nanogellant is added directly to the propellant as a monomer and is polymerized in situ to form a gel.
  • the propellant is monomethyl hydrazine (MMH) and the monomeric form of the nanogellant is bis-trimethoxysilylethane (BTMSE), which is mixed with the propellant and water.
  • MMH monomethyl hydrazine
  • BTMSE bis-trimethoxysilylethane
  • the propellant catalyzes polymerization of the nanogellant, resulting in the gelled form of the propellant.
  • the relative proportions of propellant, monomeric gellant and water are approximately 94%, 5% and 1% by weight, respectively.
  • the polymeric nanogellant is polymerized before being added to the propellant.
  • the polymenc nanogellant is first polymerized in a solvent different from the propellant, then recovered from the solvent and dried before being added to the propellant as a gellant.
  • the monomeric form of the nanogellant may also be bis-trimethoxysilylethane (BTMSE).
  • BTMSE bis-trimethoxysilylethane
  • the propellant may be monomethyl hydrazine (MMH), or some other liquid fuel, such as a cryogenic liquid fuel.
  • the invention may be defined as a method for producing a gelled propellant, comprising the steps of placing a propellant in a reaction vessel; mixing a selected monomer with the propellant in the reaction vessel; and polymerizing the monomer in the reaction vessel, and thereby forming a gelled propellant containing a nanogellant that provides the propellant with desired rheological properties and adds energy content to the propellant.
  • the selected monomer is characterized by a molecular structure that promotes formation of a three-dimensional polymer.
  • the selected monomer is soluble in the propellant and the propellant catalyzes the polymerizing step.
  • the selected monomer is bis-trimethoxysilylethane (BTMSE) and the propellant is monomethyl hydrazine (MMH).
  • BTMSE bis-trimethoxysilylethane
  • MMH monomethyl hydrazine
  • the mixing step mixes the monomer in the amount of approximately 5% by weight of the total mixture, and further adds water in the amount of approximately 1% by weight.
  • the invention comprises the steps of placing a selected monomer in a reaction vessel with a selected solvent; polymerizing the selected monomer in the reaction vessel, to produce a nanogellant polymer in solution with the selected solvent; recovering the nanogellant polymer from the solvent by a process that utilizes solvent processing or drying methods that effectively reduce or eliminate liquid surface tension during solvent removal and recovery of dry nanogellant materials. These methods include: use of surfactants, freeze drying or solvent sublimation, and super-critical or near critical point fluid processing; and dispersing the recovered nanogellant polymer in a selected propellant to form a gelled propellant.
  • the selected monomer may be bis-trimethoxysilylethane (BTMSE) and the propellant may be monomethyl hydrazine (MMH).
  • BTMSE bis-trimethoxysilylethane
  • MMH monomethyl hydrazine
  • the propellant may also be selected from other liquids, such as other forms of hydrazine and such as cryogenic liquid fuels, including liquid propane or liquid ethane.
  • the invention provides a significant advance in the field of propellants for rocket engines and the like.
  • the invention provides a technique for gelling liquid propellant fuels and oxidizers using a gellant of nanometer proportions, which provides desirable rheological and other physical properties not obtainable using conventional gallants.
  • FIG. 1 is graph showing the rheological properties of monomethyl hydrazine (MMH) propellant that has been gelled in accordance with the invention, using bis-trimethoxysilylethane (BTMSE) as the gellant.
  • MMH monomethyl hydrazine
  • BTMSE bis-trimethoxysilylethane
  • FIG. 2 is diagram showing the chemical structure of bis-trimethoxysilylethane (BTMSE) before and after polymerization.
  • FIG. 3 is a temperature-pressure phase diagram showing recovery of nanoparticulate gellant by solvent sublimation / freeze dry and critical fluid processing techniques.
  • FIG. 4 is a pair of graphs showing the rheological properties of cryogenic fuels, namely liquid propane and liquid ethane, which have been gelled in accordance with the invention using bis-trimethoxysilylethane (BTMSE) as a gellant.
  • BTMSE bis-trimethoxysilylethane
  • the present invention is concerned with gelled rocket fuels.
  • gellants for rocket propellants have been formed by mixing practically inert solid particles in suspension with a liquid propellant. Although these mixtures or suspensions have provided the desired physical properties of a gelled propellant, they have not added energy content to the fuel, which therefore does not perform as efficiently as it might.
  • a gelled propellant is produced using a polymeric gellant that also adds energy content to the fuel.
  • the gellant is formed by a process of polymerization that takes place in the liquid fuel itself. This is referred as the in-situ method.
  • the polymeric gellant is formed separately and later added to the fuel. This is referred to as the ex-situ method.
  • the polymer gellant material is produced directly in the liquid propellant by carrying out a polymerization reaction involving a selected monomer species dissolved in the liquid rocket propellant.
  • the liquid propellant is thereby converted to a semi-solid or gel, which consists of a meso-porous nano-fibril structure with entrapped liquid.
  • the gel exhibits a low yield stress compared with regular solids but it is sufficient for stably dispersing micrometer-scale and larger-scale metal and other energetic solids in the liquid propellant.
  • the monomer is converted to the nanofibril structure during the course of the polymerization reaction and typically no further processing is required, except perhaps for the addition and mixing of other energetic materials.
  • the liquid rocket propellant may be a monopropellant such as hydrazine, either mono-, di-, tri-,or tetra-methyl hydrazine, or one of the fuel-oxidizer components for a bipropellant system, such as the fuels designated RJ-4, RJ-5, RJ-7, JP-4, JP-5, JP-9, JP-10.
  • a monopropellant such as hydrazine
  • RJ-7 fuels designated RJ-4, RJ-5, RJ-7, JP-4, JP-5, JP-9, JP-10.
  • An efficacious gelling agent for mono-methyl hydrazine (MMH) is the in-situ polymer derived from the hydrolysis and condensation polymerization reaction of bis-trimethoxysilylethane (BTMSE) as shown in the following equation: n(CH 3 O) 3 Si-CH 2 -CH 2 -Si(OCH 3 ) 3 + 3nH 2 O ⁇ Polymer (Si 2 C 2 H 4 O 3 ) n + 6nCH 3 OH
  • the in-situ grown polymer is able to produce a clear MMH gel at polymer concentrations as low as 5% by weight, and unlike silica gellants has a combustion enthalpy that adds energy content to the propellant.
  • the polymerization reaction is carried out at ambient temperatures and requires a low moisture content for initiation and completion. Typical rheological properties for the MMH gel are presented in FIG. 1.
  • One of the four possible chains provides a link to a C 2 H 4 group and the other three provide links to oxygen atoms.
  • the tetrafunctional property of the structure allows it to grow efficiently in three dimensions and provide the desired mechanical gelling properties.
  • the initial concentration of water in the MMH is determined, preferably using a gas chromatographic method.
  • An amount of water to add to the MMH is then calculated to make the final mix 1.0% percent by weight water.
  • the gelling of the MMH is then carried out in a manner to exclude exposure to atmospheric moisture, carbon dioxide and oxygen. These gases can be absorbed by the MMH and detract from its value as an eventual fuel.
  • Table 1 Ingredients of Gelled MMW Monomethyl Hydrazine 94% wt/wt 1,2 Bis(trimethoxysilyl)ethane 5.0% wt/wt Water (total) 1.0% wt/wt
  • the polymerization reaction is carried out in a different solvent from the liquid propellant itself and the nanometer particulate reaction product is subsequently recovered from this reaction medium or some exchange solvent in a manner that preserves its high specific surface area and morphological structure.
  • the recovered dried nanoparticulate material may then be re-dispersed in the desired rocket propellant to produce a gelled propellant.
  • Nanoparticulate recovery in the ex-situ method uses either a drying process or a solvent elimination process in which the liquid surface tension forces are minimized or near completely eliminated. This is accomplished by taking advantage of the solvent's phase diagram and operating in a cyclic manner around either the reaction medium's or exchange solvent's triple or critical points. In FIG.
  • the paths ABCD and AB'C' are possible temperature-pressure cycles around a triple point (TP) and a critical point (CP), respectively, in the solvent's phase diagram.
  • TP triple point
  • CP critical point
  • These product recovery methods are commonly referred to as freeze drying and critical point drying.
  • surfactants or solvents with inherently very low surface tensions under ordinary ambient conditions may be used, provided these materials are selected to be effective and compatible with the monomer and polymer products.
  • FIG. 4 shows the rheological properties of ethane and propane fuels after gelling with BTMSE gellant in accordance with the ex-situ method described above.
  • MMH monomethyl hydrazine
  • other propellants such as hydrazine, di-methyl hydrazine, tri-methyl hydrazine and tetra-methyl hydrazine, are also candidates for gelling in accordance with the invention.
  • cryogenic propellants such as liquid methane, liquid ethane, liquid butane and liquid hydrogen may also be used.
  • the present invention represents a significant advance in the field of gelled rocket propellants.
  • the invention provides a gellant that can be produced either in situ to form a gel in certain categories of fuels, such as monomethyl hydrazine, or the gellant can be produced ex situ and added to various fuels. Regardless of which technique is used to produce the gelled fuel, it has desirable rheological properties that render it more useful than liquid fuels. It will also be appreciated that, although specific embodiments of the invention have been described in detail for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited except as by the appended claims.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Silicon Polymers (AREA)
EP06252111A 2005-05-10 2006-04-18 Propergol gélifié par polymère et son procédé de fabrication Withdrawn EP1721881A1 (fr)

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US11/126,845 US20060254683A1 (en) 2005-05-10 2005-05-10 Polymer-gelled propellant and method for its production

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3359144A (en) * 1964-07-23 1967-12-19 Dow Chemical Co Gelled hydrazine
US3652349A (en) * 1969-08-25 1972-03-28 Susquehanna Corp Thixotropic gas producing gel
WO1998045032A1 (fr) * 1997-04-09 1998-10-15 Cabot Corporation Procede de production de compositions en gel a faible densite
WO1999046023A1 (fr) * 1998-03-11 1999-09-16 Basf Aktiengesellschaft Procede de sechage et de production de particules microporeuses
WO2005028604A1 (fr) * 2003-09-19 2005-03-31 Genencor International, Inc. Sols-gels derives du silicate sensibles aux changements de teneur en eau
WO2005028603A1 (fr) * 2003-09-19 2005-03-31 Genencor International, Inc. Sols-gels derives du silicate sensibles aux changements de teneur en eau

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5807607A (en) * 1995-11-16 1998-09-15 Texas Instruments Incorporated Polyol-based method for forming thin film aerogels on semiconductor substrates
US6397580B1 (en) * 1998-07-09 2002-06-04 Bi-Propellant Rocket Research Corporation High performance rocket engine having a stepped expansion combustion chamber and method of making the same
US6986818B2 (en) * 2000-06-02 2006-01-17 The Regents Of The University Of California Method for producing nanostructured metal-oxides

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3359144A (en) * 1964-07-23 1967-12-19 Dow Chemical Co Gelled hydrazine
US3652349A (en) * 1969-08-25 1972-03-28 Susquehanna Corp Thixotropic gas producing gel
WO1998045032A1 (fr) * 1997-04-09 1998-10-15 Cabot Corporation Procede de production de compositions en gel a faible densite
WO1999046023A1 (fr) * 1998-03-11 1999-09-16 Basf Aktiengesellschaft Procede de sechage et de production de particules microporeuses
WO2005028604A1 (fr) * 2003-09-19 2005-03-31 Genencor International, Inc. Sols-gels derives du silicate sensibles aux changements de teneur en eau
WO2005028603A1 (fr) * 2003-09-19 2005-03-31 Genencor International, Inc. Sols-gels derives du silicate sensibles aux changements de teneur en eau

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DATABASE CA [online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; 12 May 1984 (1984-05-12), MUNJAL, N. L.: "Thixotropic cryogenic gels", XP002397262, retrieved from STN Database accession no. 98:218169 *
GESSER HYMAN D ET AL: "Aerogels and related porous materials", CHEM REV JUN 1989, vol. 89, no. 4, June 1989 (1989-06-01), pages 765 - 788, XP002396986 *
INDIAN JOURNAL OF CRYOGENICS , 7(1), 19-24 CODEN: IJCRDD; ISSN: 0379-0479, 1982 *
WAHAB MOHAMMAD A ET AL: "Bridged amine-functionalized mesoporous organosilica materials from 1,2-bis(triethoxysilyl)ethane and bis[(3-trimethoxysilyl)propyl]amine", J. SOLID STATE CHEM.; JOURNAL OF SOLID STATE CHEMISTRY OCTOBER 2004, vol. 177, no. 10, October 2004 (2004-10-01), pages 3439 - 3447, XP002396987 *

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