The application of thermal analysis in the study of reaction kinetics and reaction mechanisms in combination with presently available powerful analytical tools, in the sphere of materials with particular reference to high energy materials is presented and discussed. Also an attempt has been made to correlate the kinetic data obtained by TA with the performance characteristics, for some important materials.
Authors:J. Yi, F. Zhao, S. Xu, L. Zhang, X. Ren, H. Gao, and R. Hu
The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol
dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst
was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions.
The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can
change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can
decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol−1 under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction
mechanism function under a pressure.
It is argued that, for the macroscopic parameters of conventional kinetic models to become meaningful, they may be and must
be expressed in terms of elementary single-barrier processes. To accomplish this means to associate some (external) extensional
measure with a single-barrier elementary act, remaining within the logic of the existing geometrical-probabilistic scheme.
A manner of doing this involving the use of Dirichlet fragmentations is suggested.
Authors:B. Yan, H. X. Ma, N. N. Zhao, T. Mai, J. R. Song, F. Q. Zhao, and R. Z. Hu
-isothermal decomposition reactionkinetics, and thermal safety of DNPDNAZ were studied under 0.1 and 2 MPa by the differential scanning calorimetry (DSC) method to explore the effects of the pressure on the materials’ properties.
This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Çorum
of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25,
50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in
coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by
effluent gas analysis method. The changes in the amounts of consumed oxygen, evolved carbon oxides as well as variations in
the temperature were assessed. The combustion efficiency and effectiveness of lignite was evaluated in terms of thermal features,
from the viewpoint of reaction kinetics and by the computation of instantaneous fuel consumption at critical points. It was
seen that combustion of lignite tended to turn from a steady profile to a considerably rapid one with increase in pressure,
proving to be highly sensitive to the applied pressure level. Also, different levels of pressure resulted in distinctive combustion
behavior not only from the view of thermal characteristics, but also in terms of reaction kinetics.
Owing to increasing threats of biological attacks, new methods for the neutralization of spore-forming bacteria are currently
being examined. Thermites may be an effective method to produce high-temperature reactions, and some compositions such as
aluminum (Al) and iodine pentoxide (I2O5) also have biocidal properties. This study examines the thermal degradation behavior of I2O5 mixed with micron and nanometer scale aluminum (Al) particles. Differential scanning calorimetry (DSC) and thermogravimetric
(TG) analyses were performed in an argon environment on both particle scales revealing a non-reaction for micron Al and a
complex multistep reaction for the nanometer scale Al. Results show that upon I2O5 decomposition, iodine ion sorption into the alumina shell passivating Al particles is the rate-controlling step of the Al–I2O5 reaction. This pre-ignition reaction is unique to nano-Al mixtures and attributed to the significantly higher specific surface
area of the nanometric Al particles which provide increased sites for I− sorption. A similar pre-ignition reaction had previously been observed with fluoride ions and the alumina shell passivating
Decomposition of urea nitrate in an initially evacuated system gave sigmoidal pressurevs. time curves. The experimental kinetic data fit the growing nuclei model with a measured enthalpy of activation of 142±12.5 kJ/mole as compared to 115±11.3 kJ/mole obtained thermogravimetrically. This higher value ofΔH‡ is explained on the basis of two factors: 1) the inhibitory effect of the product gases and 2) self heating, whose extent increasedΔH‡ by about 12.5 kJ/mole.