Untitled

Special features characteristic of the use of differential scanning calorimetry for the investigation of the kinetics of thermal decomposition of energetic materials

“…The first stage (constant-rate heating mode) is described by the set of equations (4) and (5) with the initial conditions of q(0) = 0 and η(0) = 0. The second stage (isothermal mode) is described by the set of equations (17) (18) with the initial conditions…”

“…This reason consists in that the experiments are performed (a) under conditions in which the instrument significantly affects the pattern of the course of reaction in the substance under investigation (possible examples include the catalytic effect of gold in studying the thermal decomposition of some EM in golden containers [3] or the variation of permolecular structure of polymers in the course of experiments in the case of X-ray diffraction analysis [4]); and (b) under conditions in which the process of chemical reaction under investigation is complicated by physical factors including those of subjective nature (disregard of the special features characteristic of the use of equipment for the investigation of high-intensity exothermal processes, failure to provide for the necessary boundary conditions, and so on).…”

“…(1)(2)(3)(4)(5) The dimensionless heating rate Ω and (6) the critical rate Ω* as functions of the initial mass of HMX sample m 0 at heating rates b = (s. Calculation was performed for the most probable values of critical temperature. The characteristics of the sample and instrument correspond to the basic calculation version (Table 3).…”

“…The non-reproducibility of the values of α (Ψ, Bi) when using different methods and instruments is possibly one of the main reasons for very wide spread in the estimates of kinetic parameters of thermal decomposition of EM in the condensed phase. The combination of unfavorable experimental(1)(2)(3)(4) The normalized DSC signal W* and (5) the true decomposition rate W of EM as functions of temperature for values of overall thermal resistance Ψ Σ = (1) 75, (2) 750, (3) 3000, and (4) 7500 K/W. The parameters of EM are as follows: Q = 2 MJ/kg, E = 165 kJ/mol, and Z = 2.0 × 10 13 s -1 .…”

Enhanced Crystallinity of PTFE by Ion Irradiation in a Dense Plasma Focus

“…Many techniques have been applied to obtain the desired surface properties, ranging from conventional flame treatments, wet chemical treatments,7,8 incorporation of metal powders by rubbing,9 and electrical treatments (such as corona discharge),10 to modern plasma treatments7,11 and particle beam irradiation (electrons,12,13 photons, 14,15 neutrons and ions7,16–18). It is well established that irradiation of PTFE not only induces growth of the crystallinity degree,19 but also creates more bioactive surfaces,5 improves the adhesion with metallic films,16 increases the wettability,20 improves the mechanical properties,21 produces more favorable surface for graft copolymerization,22 increases the electrical conductivity,13 improves cell adhesion control for biomedical applications23 etc. The possible chemical reactions induced by the incident radiation on the surface of PTFE include defluorination, chain scission and crosslinking.…”