Rate of the exothermic decomposition reaction

Incidentally, the effect of the concentration of a chemical of the TD type on the rate of the exothermic decomposition reaction, in the early stages of the selfheating process, of the chemical is assumed to be of the zeroth order in the thermal explosion theory [1], In other words, it is assumed in the thermal explosion theory that the concentration of the chemical remains virtually constant while the self-heating process is in the early stages, because the consumption of the chemical caused by the reaction can be neglected while the self-heating process is in the early stages. 

In the meantime, the A Tdijf pen runs almost parallel with the time axis on the strip chart of the two-pen strip-chart recorder after the start of the adiabatic control. This denotes that the state, A - T - Tqiiii 0, IS rcslizcd. in 8.nd around 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test. The A Tdiff pen, however, comes to drift toward the plus side on the strip chart in the course of time. This denotes that the state, 7 > Tam, comes to occur in and around 2 cm of the chemical confined in the closed cell, in spite of the adiabatic control, because the rate of increase in temperature, i.e., the rate of the exothermic decomposition reaction, of 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test... 

Frequency factor in the rate constant of the exothermic decomposition reaction, of the zeroth order, of a chemical of the TD type, including every gas-permeable oxidatively-heating substance or, frequency factor in the rate constant of the decomposition reaction, of the zeroth order, of a high explosive of the true AC type to generate the autocatalyst [mol/(cm min)]. 

When AN particles are mixed with GAP, AN-GAP composite propellants are formulated. The specific impulse is increased by approximately 10 s by replacing PB or PU binder with GAP, as shown in Fig. 4.16. The burning rate is also increased due to the exothermic decomposition of GAP. Since GAP burns by itself, the burning of the AN particles is supported by the exothermic decomposition reaction of the GAP at the burning surface of the propellant. As shown in Fig. 7.61, the burning rate is drastically decreased by the addition of AN particles. When is in-... 

Self-Accelerating Decomposition Temperature The minimum temperature that a mass of material, capable of an exothermic decomposition reaction, must be held such that the heat of decomposition exceeds the amount of energy lost to the surroundings. This will result in an increase in the mass temperature and acceleration of the decomposition reaction rate. 

Amines and other bases cataly2e the exothermic decomposition of molten maleic anhydride [108-31-6] at temperatures above 150°C, accompanied by the rapid evolution of gaseous products (44,45). The rate of reaction reportedly increases with the basicity of the amine and higher initial temperatures. The reaction mixture can become explosive. 

As well as the normal addition reaction, an extremely exothermic decomposition reaction may occur, particularly at high vessel loadings. At loadings of 0.8 ml of 1 1 mixture per ml, the violent reaction, catalysed by iron(III) chloride, initiates at —40°C and will attain pressures above 0.7 kbar at the rate of 14 kbar/s. At 0.5 ml loading density, a maximum pressure of 68 bar, attained at 114 bar/s, was observed. 

All reactive hazards involve the release of energy in quantities or at rates too high to be absorbed by the immediate environment of the reacting system, and material damage results. The source of the energy may be an exothermic multi-component reaction, or the exothermic decomposition of a single unstable (often endothermic) compound. 

The observed onset temperature, T0, is the temperature at which the substance or mixture first shows an observable instrumental response due to decomposition or reaction. The value of this To depends on the sensitivity of the apparatus, the sample mass, the atmosphere, the confinement, and the heating rate. When the experiment is designed to establish the onset temperature of the exotherm with more accuracy, a heating rate of 1 to 5°/min is appropriate [23,77,81,82]. However, it should be emphasized again that the onset temperature value strongly depends on the instrument sensitivity and that application of onset temperature, and kinetic data, obtained in the DSC to large-scale operations may introduce significant errors. 

Burn-rate modifiers probably affect most of these combustion steps, that is, the endothermic and exothermic reactions and heat losses. Rastogi et al. have shown that burn rate, surface temperature, flame temperature and rate of decomposition are enhanced in case of catalyzed propellants while these are lowered in case of burn-rate retarders. This may be due to heat produced in catalytic reactions in the former case whereas bum rates are reduced on account of endothermicity of the condensed phase reactions on the propellant surface in the case of retarders. It is also reported that carbonates of copper and chromium are better catalysts... 

Figure 6.5 shows the DTA plot for the decomposition of an explosive material. Decomposition begins when the temperature T reaches the ignition temperature of the explosive material resulting in an exothermic peak. As the explosive material decomposes it releases heat which is measured on the DTA plot as AT(y-axis). AT is proportional to the rate at which the explosive material decomposes as the rate increases more heat is emitted and AT increases. Assuming that the decomposition of an explosive is a first order process, then the rate of the reaction is directly proportional to the increase in temperature AT, as shown in Equation 6.15. 

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