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The Kinetics of Thermal Decomposition and Hot-Stage Microscopy of Selected Energetic CocrystalsJoshua Trevett Dean (8782151) 29 April 2020 (has links)
<p>The thermal decomposition of four energetic cocrystals
composed of 4-amino-3,5-dinitropyrazole (ADNP)/diaminofurazan (DAF),
2,4,6-trinitrotoluene (TNT)/
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL20), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane
(HMX)/CL20, and 1-methyl-3,5-dinitro-1,2,4-triazole (MDNT)/CL20 were studied
using simultaneous differential scanning calorimetry (DSC), thermogravimetry
analysis (TGA), and hot-stage microscopy. The kinetic parameters of their
thermal decomposition reaction were determined using the Kissinger and Ozawa
kinetic analysis methods. Each cocrystal’s peak exothermic temperature
(decomposition temperature), activation energy, and pre-exponential constant are
reported. Furthermore, these parameters from each cocrystal were compared to
the same parameters from the corresponding stoichiometric physical mixture in
order to identify changes in behavior attributable to the cocrystallization
process. For ADNP/DAF, the cocrystal shows an 8% increase in the peak exotherm
temperature and a 11-13% decrease in peak activation energy as compared to its
physical mixture. For TNT/CL20, this comparison shows a much smaller change in
the peak exotherm temperature (<1%) but shows a 5% decrease in activation
energy. This cocrystal also experiences phase stabilization—where a phase
transition of one or both coformers is omitted from the decomposition process. The
HMX/CL20 cocrystal shows a 1% change in the peak exotherm temperature and shows
a 2% increase in activation energy. Finally, for MDNT/CL20, this comparison
shows nearly a 4% increase and a drastic decrease in peak activation energy by 42-44%.
Cocrystallization clearly affects the thermal decomposition and reaction
kinetics of these materials, offering the potential to create a hybrid-class of
energetic materials which combines the high performance of an energetic
material with the safety and insensitivity of another. </p>
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Určení kinetických parametrů reakcí pomocí DSC měření / determination of kinetic parameter of reactions using DSCKopecký, Jan January 2018 (has links)
The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.
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