Thiokol Corporation

Robert E Askins

Jamie B Neidert

William H Graham

Robert L Stanley

Compositions and methods for increasing the storage life of a propellant grain by reducing the rate of decomposition of its nitrate ester components. A nitrate ester stabilizer is placed in a layer adjacent to a nonburning surface of the propellant grain. The stabilizer migrates from the layer into the grain's nonburning surface to provide additional stabilization for the entire grain, especially portions of the grain adjacent to the protected nonburning surface.

Nitrate ester stabilizing layer for propellant grain

Propellant formulations are provided which include non-toxic burn rate modifiers. In order to produce a usable propellant formulation, it is necessary to control the burn rate of the propellant. Failure to adequately control the propellant burn rate often results in unacceptable performance of the propellant. For example, during the operation of a rocket motor, or similar device which contains a propellant, the propellant may produce operating pressures which are too high or too low for the intended purpose of the device. It has often been the practice to add lead to rocket motor propellants in order to modify the burn rate and to maintain the burn rate within acceptable parameters. Lead, however, is known to be toxic and a pollutant. Accordingly, it is desirable to replace the lead in the formulation. It has been found herein that bismuth trioxide is capable of modifying the burn rate of propellants without resorting to lead as a burn rate additive. Accordingly, the use of bismuth trioxide is taught as effective burn rate modifiers in propellants, in order provide non-toxic means for modifying the propellant burn rate.

Burn rate modification of solid propellants with bismuth trioxide

Propellant formulations are provided which include non-toxic burn rate modifiers. In order to produce a usable propellant formulation, it is necessary to control the burn rate of the propellant. Failure to adequately control the propellant burn rate often results in unacceptable performance of the propellant. It has been found that carbon fibers are capable of modifying the burn rate of propellants without resorting to lead as a burn rate additive. Accordingly, the use of from about 0.5% to about 6.0% carbon fibers is taught as effective burn rate modifiers in propellants, in order provide non-toxic means for modifying the propellant burn rate.

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Huntsville, AL, United States of America

Robert E Askins