| The objective of this work was to alter physical and chemical aspects of several series of energetic materials to determine the effects on decomposition and initiation.; In one category of study, very fine particle sizes in a homogeneously distributed formulation should help shift the balance of decomposition from transport control to chemical kinetic control in the hope of decreasing the impact sensitivity. Nano scale particles (20–50 nm in 400–800 nm aggregates) of the highly impact-sensitive hydrazinium diperchlorate ([N 2H6][ClO4]2, or HP2) in a resorcinol-formaldehyde (RF) matrix was investigated in a range of stoichiometries. The production method was to synthesize a sol-gel matrix containing dissolved energetic material and crystallize it by freeze-drying (the cryogel method). A second cryogel system was investigated comprised of two energetic components, a hexanediisocyanate crosslinked nitrocellulose gel matrix containing nano-dimensional particles of hexanitrohexaazaisowurtzitane (CL-20). By the use of transmission electron and atomic force microscopy, this novel material appeared to contain essentially spherical nanoscale particles of CL-20 coated by hexanediisocyanate (HDI)-crosslinked nitrocellulose. The properties of both cryogel systems were compared to those of conventional physical mixtures having the same composition by the use of T-jump/FTIR spectroscopy, DSC, SEM, and drop height impact tests. Improvements regarding energy release, impact sensitivity and reaction kinetics are discussed.; In another study, energetic salts, namely the alkali metal series of monoanionic and di-anionic 5-nitraminotetrazole salts, were synthesized and characterized to determine the structure, physical properties and decomposition behavior. Single crystal x-ray diffraction structures were the first of the mono-anionic and di-anionic 5-nitraminotetrazole salts reported. The major atom motions in the IR spectra of the neutral, mono-anion and di-anion were assigned on the basis of density functional theory using the B3LYP method. The thermal stability determined by DSC increases as each acidic hydrogen atom is removed; i.e., the decomposition temperatures follow the order di-anion > mono-anion > neutral. T-jump/FTIR spectroscopy showed a difference in decomposition channels that yielded a difference in energy release in this same order. |
