Polymer-gelled propellant and method for its production

Abstract

A liquid propellant is converted to a gelled propellant by use of a nanogellant material having a three-dimensional polymeric structure that either is formed in the propellant itself, or is formed separately from the propellant and later dispersed in the propellant. In one form of the invention, the nanogellant material is bis-trimethoxysilylethane (BTMSE), which, when mixed with a suitable liquid propellant, such as monomethyl hydrazine (MMH), in the presence of water, polymerizes to form a gelled propellant with desirable properties. In the other form of the invention, the nanogellant is polymerized in a solvent separate from the propellant, and is then recovered from the solvent and redispersed in the propellant.

1 . 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;    wherein the gelled propellant has desirable Theological properties and the polymeric nanogellant adds energy content to the propellant.    
   
   
       2 . A gelled propellant as defined in  claim 1 , wherein the monomer is characterized by the chemical formula  
       (R a O) 3 Si—C n H 2n-y (NH 2 ) y —Si(OR a ) 3    
     where: 
 R a ═—CH 3 , —C 2 H 5 , or —C 3 H 7 ,  
 2≦n≦6, and  
 y≦2n.  
 
   
   
       3 . A gelled propellant as defined in  claim 2 , wherein the polymeric nanogellant is added directly to the propellant as a monomer and is polymerized in situ to form a gel.  
   
   
       4 . A gelled propellant as defined in  claim 3 , wherein: 
 the propellant is monomethyl hydrazine (MMH);    the monomeric form of the nanogellant is bis-trimethoxysilylethane (BTMSE), which is mixed with the propellant and water; and    the propellant catalyzes polymerization of the nanogellant, resulting in the gelled form of the propellant.    
   
   
       5 . A gelled propellant as defined in  claim 4 , wherein the proportions of propellant, monomeric gellant and water are approximately 94:5:1 by weight, respectively.  
   
   
       6 . A gelled propellant as defined in  claim 2 , wherein the polymeric nanogellant is polymerized before being added to the propellant.  
   
   
       7 . A gelled propellant as defined in  claim 6 , wherein the polymenc nanogellant is polymerized in a solvent different from the propellant, then recovered from the solvent and dried before being added to the propellant as a gellant.  
   
   
       8 . A gelled propellant as defined in  claim 7 , wherein the monomeric form of the nanogellant is bis-trimethoxysilylethane (BTMSE).  
   
   
       9 . A gelled propellant as defined in  claim 8 , wherein the propellant is form of hydrazine.  
   
   
       10 . A gelled propellant as defined in  claim 8 , wherein the propellant is a cryogenic liquid fuel.  
   
   
       11 . A method for producing a gelled propellant, comprising: 
 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.    
   
   
       12 . A method as defined in  claim 11 , wherein: 
 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.    
   
   
       13 . A method as defined in  claim 12 , wherein the monomer is characterized by the chemical formula  
       (R a O) 3 Si—C n H 2n-y (NH 2 ) y —Si(OR a ) 3    
     where: 
 R a ═—CH 3 , —C 2 H 5 , or —C 3 H 7 ,  
 2≦n≦6, and  
 y≦2n.  
 
   
   
       14 . A method as defined in  claim 13 , wherein the selected monomer is bis-trimethoxysilylethane (BTMSE).  
   
   
       15 . A method as defined in  claim 13 , wherein the propellant is monomethyl hydrazine (MMH).  
   
   
       16 . A method as defined in  claim 13 , wherein 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.  
   
   
       17 . A method for producing a gelled propellant, comprising: 
 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 selected from freeze drying and critical point drying; and    dispersing the recovered nanogellant polymer in a selected propellant to form a gelled propellant.    
   
   
       18 . A method as defined in  claim 17 , wherein the monomer is characterized by the chemical formula  
       (R a O) 3 Si—C n H 2n-y (NH 2 ) y —Si(OR a ) 3    
     where: 
 R a ═—CH 3 , —C 2 H 5 , or —C 3 H 7 ,  
 2≦n≦6, and  
 y≦2n.  
 
   
   
       19 . A method as defined in  claim 18 , wherein the selected monomer is bis-trimethoxysilylethane (BTMSE).  
   
   
       20 . A method as defined in  claim 18 , wherein the propellant is a form of hydrazine.  
   
   
       21 . A method as defined in  claim 18 , wherein the propellant is a cryogenic liquid fuel.  
   
   
       22 . A method as defined in  claim 21 , wherein the propellant is selected from the group consisting of liquid propane, liquid ethane and liquid methane.