US Government As Represented by the Secretary of the Army

Everette M Pierce

Henry C Allen

The propellant compositions of this invention are crosslinked with from at 0.1 to about 1.0 weight percent of nitrocellulose which improves the physical properties and the thermal stabilities of these propellants thereby permitting their storing and testing up to 165.degree. F. These propellants employ additional ingredients which include one or more binder ingredients selected from the group consisting of polyglycol adipate (PGA), polyethylene glycol (PEG), polycapralactone (PCL or PCP), and hydroxy-terminated polybutadiene (HTPB); plasticizer ingredients selected from the nitrate ester plasticizers consisting of nitroglycerin (NG), trimethylol ethane trinitrate (TMETN), triethylene glycol dinitrate (TEGDN), and butane trioltrinitrate (BTTN); oxidizer ingredient selected from the group consisting of cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), triaminoguanidine nitrate (TAGN), and oxamide; thermal stabilizers selected from the group consisting of 2-nitrodiphenylamine, 4-nitrodiphenylamine, n-methyl-p-nitroaniline, and resorcinol; isocyanate curing agent; carbon black additive; and a modifying additive selected from ballistic additives and curing catalyst additives.

Smokeless propellant compositions having polyester or polybutadiene

A liner composition is employed as a liner/inhibitor for a solid propellant rain while functioning as a liner-binder between the propellant grain and insulation or the motor case. The liner and inhibitor composition is prepared from the conventional binder systems (e.g., hydroxy terminated polybutadiene (HTPB), polysulfide, polyurethane, and polyester). The composition employs a cool burning oxidizer selected from oxamide and nitroguanidine. The type of solid propellant grain, particularly the crosslinking or reaction mechanism to form a chemical bond between the binder of the liner composition and the binder of the propellant, dictates the type formulation of the liner/inhibitor composition. A representative liner/inhibitor for a HTPB propellant grain contains from about 10 to about 70 weight percent oxidizer, from about 0.1 to about 1.0 weight percent cure catalyst selected from ferric acetyl acetonate and triphenyl bismuth, an isocyanate curing agent selected from toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate from about 1 to about 10 weight percent, and the balance of formulation hydroxy terminated polybutadiene. The use of the proper cure catalyst will produce a cured system at ambient (70.degree. F. or higher) in 24 hours. A chemical bond is formed between the liner and inhibitor binder and the propellant binder by the crosslinking action of the isocyanate curing agent and the hydroxyl groups of the binder systems. The chemical bond withstands the stresses of gas flow as well as the effects of spinning the rocket motor. Thus, the cool burning oxidizer in combination with the bonds between the binder systems which withstands the flow of gases will result in extinguishment of the liner/inhibitors at sudden pressure drop encountered at end of propellant grain burning and thereby result in elimination of smoke from the liner/inhibitor which is extinguished prior to bond failure.

Ambient cured smokeless liner/inhibitor for propellants

An oxidizer that is soluble in a polar solvent selected from ethanol, diel ether, and acetone is used in a propellant composition mixing procedure to effect an improved dispersion of the oxidizer. The soluble oxidizer is selected from the reaction products formed by reacting together an equivalent amount of a first reactant selected from triethanol amine or diethanol amine with an equivalent amount of a second reactant perchloric acid when the soluble perchlorate salt is desired for use. The soluble oxidizer is selected from the reaction products formed by reacting together an equivalent amount of a first reactant selected from triethanol amine or diethanol amine with an equivalent amount of a second reactant nitric acid when the soluble nitrate salt is desired for use. The dissolved oxidizer is added to the binder portion of the propellant during mixing. After being widely dispersed, the soluble oxidizer and binder portion are mixed under low vacuum and mild heat (e.g., 110.degree. F. to 120.degree. F.) to remove the polar solvent thereby leaving the oxidizer in a widely dispersed state. The other propellant ingredients are added and mixing is continued to achieve homogenity prior to forming and curing the propellant for its intended use. The propellant composition with the widely dispersed oxidizer shows improved burning rate.

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Somerville, AL, United States of America

Everette M Pierce