Thiokol Corporation

Morton Thiokol Inc.

Inella G Shepard

William H Graham

James D Byrd

Kenneth E Junior

Kenneth E Bevel

Process for forming a liner and cast propellant charge in a rocket engine casing without separately precuring the liner, comprising the steps of providing a blocked curable liner composition which is the reaction product of a prepolymer, an isocyanate curing agent, and a blocking agent; applying the liner composition to an internal surface of a rocket casing; preheating the casing and liner assembly to simultaneously prepare the assembly for receiving a propellant, unblock the liner, and precure the liner to a tacky state; casting the propellant change into interfacial contact with the liner; and cocuring the liner and propellant compositions. The blocked, curable liner composition has a very long pot life which is terminated by heating the composition sufficiently to uncouple the blocking agent from the isocyanate curing agent and initiate a rapid cure. The liner composition does not require precuring, as it is unblocked by preheating the liner and rocket casing sufficiently to receive to cast propellant. The blocked liner composition has the following structure. ##STR1##

Process for forming a liner and cast propellant charge in a rocket motor

Salicylate esters have been found to be suitable blocking agents for polyisocyanates, enabling preparation of hydroxy terminated polybutadiene based polyurethane bound propellant grains having extended pot life. Unblocking occurs readily at normal propellant cure temperatures, allowing normal cure rates.

Hydroxy terminated polybutadiene based polyurethane bound propellant

Curing catalysts comprising organo metallic compounds, and carboxylic acids or compounds convertible thereto, processes for their use and compositions containing them are disclosed. The compositions enable the control of the curing rate profile of hydroxy terminated polybutadiene based urethane propellant binders, and the cure rate profile of polyurethane resin systems generally.

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Huntsville, AL, United States of America

Inella G Shepard