Abstract: Bonding agents for use in formulating solid propellants are described. The bonding agents have a Schiff base, or Schiff base and hydroxyl or amine functionality. These materials are synthesized by reacting a primary amine with an aldehyde to form a Schiff base. By definition, a Schiff base comprises the reaction product of a primary amine and an aldehyde. In one embodiment of the invention, such a product is produced by the reaction of a polyoxyalkyleneamine (JEFFAMINE®) with p-nitrobenzaldehyde and glycidol. The result is a polyether having both hydroxyl and Schiff base functionality. The bonding agents provide superior performance, while avoiding problems, such as ammonia production during processing, encountered when using existing bonding agents. Propellants formulated using these bonding agents have mechanical properties within acceptable ranges.

Abstract: A method of crystallizing an epsilon-polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05,903,11]-dodecane (CL-20). The method comprises combining the CL-20, at least one organic solvent, and at least one nonsolvent to form a crystallization solution. The crystallization solution is saturated and heated to a temperature greater than about 60° C., such as from about 71° C. to about 94° C. The organic solvent is removed from the crystallization solution while retaining a sufficient amount of the nonsolvent to crystallize the CL-20 as the epsilon-polymorph. The nonsolvent is separated from the epsilon-polymorph of CL-20. A composition of CL-20 comprising the epsilon-polymorph having a particle density of 2.035 g/ml is also disclosed.

Abstract: A method is provided in which 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05,903,11]-dodecane (CL-20 or HNIW) is crystallized to its ?-polymorph by an inverse precipitation technique. A dry CL-20 solvent solution containing an amount of CL-20 dissolved in a CL-20 solvent is prepared. The dry solvent solution is added to a crystallizer containing a CL-20 non-solvent to cause precipitation of epsilon polymorph CL-20 crystals by the inverse precipitation technique. The precipitated epsilon polymorph CL-20 crystals are separated from the non-solvent and the solvent.

Abstract: A method is provided in which 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05,903,11]-dodecane (CL-20 or HNIW) is crystallized to its &egr;-polymorph by an inverse precipitation technique. A dry CL-20 solvent solution containing an amount of CL-20 dissolved in a CL-20 solvent is prepared. The dry solvent solution is added to a crystallizer containing a CL-20 non-solvent to cause precipitation of epsilon polymorph CL-20 crystals by the inverse precipitation technique. The precipitated epsilon polymorph CL-20 crystals are separated from the non-solvent and the solvent.

Abstract: There is provided an improved process for preparing a composite propellant comprising (a) a polymeric binder, (b) a bonding agent, (c) a curing agent for the binder, (d) a metallic fuel, and (e) an ammonium salt oxidizer wherein the improvement resides in adding the metallic fuel to the propellant mix after all of the ammonium salt oxidizer has been added to the propellant mix.

Abstract: Difunctional, hydroxyl-terminated polymers in which the terminal hydroxyl group is non-primary or hindered are end-capped to provide unhindered, primary, terminal hydroxyl groups which promote an improved cure and improved mechanical properties of the cured elastomer. End-capping chemicals have an hydroxyl-reactive group at one end and a group at the other end which is removable to provide a primary, unhindered hydroxyl group. Short-chain, hydroxyl-terminated polymers are chain-extended with a diisocyanate.

Abstract: A nonsolvent process of synthesizing bis(2,2-dinitropropyl)acetal (BDNPA) is disclosed. In the process, 2,2-dinitropropanol (DNPOH) is reacted at low temperature with an acetaldehyde source in the presence of an acid catalyst, such as a Lewis acid catalyst or protic acid catalyst. To inhibit by product formation, the reaction temperature is maintained from about -30.degree. C. to 30.degree. C. Upon completion of the reaction, the reaction solution is quenched with water and washed with an aqueous hydroxide solution. The hydroxide concentration should be sufficient to neutralize any acid formed during the quenching step and to solubilize unreacted 2,2-dinitropropanol as well as other aqueous soluble byproducts in the reaction solution. The BDNPA product is extracted with methyl tert-butyl ether (MTBE) or equivalent solvent. The organic solvent is evaporated to yield usable BDNPA product. The resulting yield is at least 50% based on the starting quantity of 2,2-dinitropropanol.

Abstract: A PBAN-based solid rocket motor propellant which includes more than 85% or more solids is provided. Propellants of this nature are possible using the combination of diepoxide curing agents and PBAN as a binder. The curing agents include diepoxides having 4 to about 10 carbon atoms. It has been observed that when a diepoxide curing agent is substituted for conventional curing agents, viscosities are significantly reduced, thus enabling the addition of higher percentages of solids in the propellant formulation. Total solids loading of over 85% are achievable while maintaining end-of-mix viscosities within acceptable ranges.

Abstract: Conductive carbon fibrils are incorporated into energetic compositions to reduce electrostatic discharge susceptibility. The carbon fibrils are grown catalytically from carbon precursors and are substantially free of pyrolytically deposited thermal carbon. The fibrils generally have a length in the range from about 1.mu. to about 10.mu. and a diameter in the range from about 3.5 nanometers to about 75 nanometers. Length to diameter aspect ratios are greater than 5, and typically in the range from about 100:1 to about 1000:1. An effective amount of fibrils is included in the energetic compositions to decrease the resistivity to a level below or on the order of about 10.sup.10 ohm-cm. In most cases, fibril concentration will be in the range from about 0.005 to about 0.1 weight percent.

Abstract: A nonsolvent process of synthesizing bis(2,2-dinitropropyl)formal (BDNPF) is disclosed. In the process, 2,2-dinitropropanol (DNPOH) is reacted at low temperature with a formaldehyde source in the presence of a protic acid catalyst, such as H.sub.2 SO.sub.4, HCl, H.sub.3 PO.sub.4, or HBr. To inhibit byproduct formation, the reaction temperature is maintained from about -30.degree. C. to 30.degree. C. Upon completion of the reaction, the reaction solution is quenched with water and washed with an aqueous hydroxide ion solution. The hydroxide ion concentration should be sufficient to neutralize the protic acid catalyst during the quenching step and to solubilize unreacted 2,2-dinitropropanol as well as other aqueous soluble byproducts in the reaction solution. The BDNPF product is extracted with a low boiling temperature polar organic solvent, such as methyl tert-butyl ether (MTBE) or equivalent solvent. The organic solvent is evaporated to yield usable BDNPF product.

Abstract: Polyether organic compounds are described which have both imine and hydroxyl functionality. These materials are synthesized by reacting a primary amine with an aldehyde or ketone to form a Schiff base. By definition, a Schiff base comprises the reaction product of a primary amine and an aldehyde. In this case, however, unlike conventional Schiff bases, the reaction product possesses both hydroxyl and Schiff base functionality. In one embodiment of the invention, such a product is produced by the reaction of a polyoxyalkyleneamine (Jeffamine) with p-nitrobenzaldehyde and glycidol. The result is a polyether having both hydroxyl and Schiff base functionality. The compounds produced in this manner are particularly useful as bonding agents in the formulation of solid propellants. The bonding agents provide superior performance, while avoiding the problems encountered when using existing bonding agents.

Abstract: Oxazolines useful as bonding agents in solid rocket propellants are disclosed. The oxazoline bonding agents are capable of polymerizing in the presence of ammonium perchlorate. The bonding agents of the present invention are added to the propellant in a range from about 0.1% to about 3% concentration. Importantly, there is no increase in ammonia liberated above baseline propellant values and no increase in end of mix viscosities by using the oxazolines according to the present invention which provides substantial processing savings.

Abstract: Vinyl ethers for use as bonding agents in solid rocket propellants are disclosed. The vinyl ether bonding agents are capable of polymerizing in the presence of and around the surface of ammonium perchlorate particles. The bonding agents of the present invention are added to the propellant in a range from about 0.1% to about 3% by weight concentration. Importantly, there is no increase in ammonia liberated above baseline propellant values and no increase in end of mix viscosities by using the vinyl ethers according to the present invention which provides substantial processing savings.