During World War II, it was discovered that when lead was added to double-base propellants, it produced beneficial burn rate phenomena. Specifically, the propellant burn rate first increased unexpectedly at low pressures, then the burn rate became independent of pressure, followed lastly by “mesa burning” where the burn rate actually decreased with increasing pressure. This results in a beneficial negative feedback mechanism. Over the past 75 years, researchers have explored different lead complexes to achieve better propellant performance. However, over the last decade, research has shifted to finding an alternative to using lead as an additive to reduce toxicity. Until the attempts detailed herein, researchers had not, to our knowledge attempted to combine double-base propellant stabilizers with various metals to achieve these desired results. In doing so, we prepared two lead complexes, Tetrakis (µ3-(4-methyl-3-nitrophenyl imido lead (II))) 1, and Bis(dinitrophenyl imido lead(II)) 2, that were synthesized by reacting lead bis(trimethylsilyl)amide with a common double-base propellant stabilizer 2-nitrodiphenylamine (NDPA) and 4-methyl-3-nitroaniline. Both complexes formed from protolysis of the trimethylsilylamide ligand by the acidic proton of the amine, and crystallized from tetrahydrofuran (THF). Bomb calorimetry coupled with crystal density structure determined that 1 has a very high energy density of 74.1 MJ/L, more than three times the energy density of conventional nitroamine explosives, whereas 2 was lower at 38.2 MJ/L. The structure, charge and characterization of 1 and 2 are discussed. However, each complex is air sensitive making burn rate experimentation infeasible, so any possible changes to the propellant as an additive remained undetermined. Attempts to use of tin, zinc, or bismuth bis(trimethyl)amides in place of lead, were unsuccessfully characterized, although reactions were likely observed. / Chemistry

<p>Additive manufacturing of gun propellants is an emerging and promising field which addresses the limitations of conventional manufacturing techniques. Gun propellants are manufactured using wetted extrusion, which uses volatile solvents and dies of limited and constant geometries. On the other hand, additive techniques are faced with the challenges of maintaining the gun propellant’s energetic content as well as its structural integrity during high pressure combustion. The work presented in this thesis demonstrates the feasibility of producing functioning gun propellant grains using vibration-assisted 3D printing, a novel method which has been shown to extrude extremely viscous materials such as clays and propellant pastes. At first, the technique is compared to screw-driven additive methods which have been used in printing gun propellant pastes with slightly lower energetic content. In chapter two, diethylene glycol dinitrate (DEGDN), a highly energetic plasticizer, was investigated due to its potential to replace nitroglycerin in double base propellants with high nitroglycerin content. A novel isoconversional method was applied to analyze its decomposition kinetics. The ignition and lifetime values of diethylene glycol dinitrate were obtained using the new isoconversional method, in order to assess the safety of using the plasticizer in a modified double base propellant. In chapter three, a modified double base propellant (M8D) containing DEGDN was additively manufactured using VAP. The printed strands had little to no porosity, and their density was nearly equal to the theoretical maximum density of the mixture. The strands were burned at high pressures in a Crawford bomb and the burning was visualized using high speed cameras. The burning rate equation as a function of the M8D propellant as a function of pressure was obtained. Overall, this work shows that VAP is capable of printing highly energetic gun propellants with low solvent content, low porosity, with high printing speeds, and which have consistent burning characteristics at high pressures. </p>