Minimum decomposition temperature

The decomposition does not take place at room temperature because the chemical potential of the reactant is smaller than the combined potentials of the products. However, since a gas that means a substance with strongly negative temperature coefficient a should be formed, we expect that this process will start at a high enough temperature (Fig. 8). The minimum decomposition temperature is obtained from the condition that the combined chemical potentials of the initial and final substances have to be equal. The calculation yields to a similar equation as equation (8). Inserting the g and a values results in 465 K. 

The Hazard Evaluation Chemist quantifies the actual potential hazards involved in an operation - heats of reaction, gas evolution rates, minimum decomposition temperatures, etc. 

The thermal decomposition of polymers may proceed by oxidative processes or simply by the action of heat. In many polymers, the thermal decomposition processes are accelerated by oxidants (such as air or oxygen). In that case, the minimum decomposition temperatures are lower in the presence of an oxidant. Of particular interest is the fact that the effect of oxygen (or air) on thermal decomposition depends on the mechanism of polymerization free-radical polymerization leads to a neutralization of the effect of oxygen. A study on poly(vinylidene... 

Modification of the polymer to reduce ease of ignition, by increasing minimum decomposition temperature or minimum ignition temperature, or by increasing the energy required for decomposition or ignition. Phosphorus and halogen compounds appear effective in this approach. 

The controlled thermal decomposition of dry aromatic diazonium fluoborates to yield an aromatic fluoride, boron trifluoride and nitrogen is known as the Schiemann reaction. Most diazonium fluoborates have definite decomposition temperatures and the rates of decomposition, with few exceptions, are easily controlled. Another procedure for preparing the diazonium fluoborate is to diazotise in the presence of the fluoborate ion. Fluoboric acid may be the only acid present, thus acting as acid and source of fluoborate ion. The insoluble fluoborate separates as it is formed side reactions, such as phenol formation and coupling, are held at a minimum temperature control is not usually critical and the temperature may rise to about 20° without ill effect efficient stirring is, however, necessary since a continuously thickening precipitate is formed as the reaction proceeds. The modified procedure is illustrated by the preparation of -fluoroanisole ... 

Fluoroaromatics are produced on an industrial scale by diazotization of substituted anilines with sodium nitrite or other nitrosating agents in anhydrous hydrogen fluoride, followed by in situ decomposition (fluorodediazoniation) of the aryldiazonium fluoride (21). The decomposition temperature depends on the stabiHty of the diazonium fluoride (22,23). A significant development was the addition of pyridine (24), tertiary amines (25), and ammonium fluoride (or bifluoride) (26,27) to permit higher decomposition temperatures (>50° C) under atmospheric pressure with minimum hydrogen fluoride loss. 

Metal chelates afford a better initiating system as compared to other redox systems since the reactions can be carried out at low temperatures, thus avoiding wastage reactions due to chain transfer. Homopolymer formation is also minimum in these systems. It was observed by Misra et al. [66,67] that the maximum percentage of grafting occurs at a temperature much below the decomposition temperature of the various metal chelates indicating that the chelate instead of undergoing spontaneous decomposition receives some assistance either from the solvent or monomer or from both for the facile decomposition at lower temperature. The solvent or monomer assisted decomposition can be described as ... 

Certain compounds, when held at moderate ambient temperatures for an extended period of time, may undergo an exothermic reaction that accelerates with increase in temperature. If the heat liberated by this reaction is not lost to the environment, the bulk material increases in temperature, which leads to an increase in the rate of decomposition. Unchecked, the temperature grows exponentially to a point at which the decomposition cannot be stopped or slowed. The minimum temperature at which this exponential growth occurs in a material packed in its largest standard shipping container is defined as the self-accelerating decomposition temperature. Self-accelerating decomposition temperature is a measure of the... 

Remark 1 The problem statement is identical to the problem statement of section 8.5.3.1 for the synthesis of HENs without decomposition (Ciric and Floudas, 1991). Note that as in section 8.5.3.1, there is no specification of any parameters so as to simplify or decompose the original problem into subproblems. In other words, the level of energy recovery (specified by fixing H RAT), the minimum approach temperature (EM AT), and the number of matches are not specified a priori. As a result, there is no decomposition into subnetworks based on the location of the pinch point(s), but instead the pinch point(s) are optimized simultaneously with the matches and the network topology. The approach presented for this problem is from Yee and Grossmann (1990) and is an alternative approach to the one of HEN synthesis without decomposition proposed by Ciric and Floudas (1991), and which was presented in section 8.5.3. 

The Seveso accident in 1976 also involved the glycol-based process, but differed fundamentally from the 1968 incident. While the latter apparently involved a thermal runaway initiated during the hydrolysis reaction by application of excessive heat by the faulty hot oil system [7], the process design adopted by Icmesa at Seveso featured heating the reaction vessel by steam at 12 bar (192°C if saturated) to ensure a minimum 40°C safety margin below the known decomposition temperature of 230°C [5]. At Seveso the exothermic hydrolysis reaction had been completed, but... 

The reaction conditions are constrained. In other words, there is usually a strict upper and lower limit for each reaction parameter. In the case of the synthesis described above, for example, the lower temperature is set by the need to provide sufficient thermal energy to initiate the reaction and the upper temperature by the need to remain below the decomposition temperature of the glue (see Section 2). The lower and upper limits on the total flow rate meanwhile are determined, respectively, by the maximum length of time one is prepared to allow for a single reaction and the minimum reaction time needed to produce crystals of nanometer dimensions. In this work, we select minimum and maximum total flow rates of 2 and 40 il min 1 which, for the typical chip volumes we use ( 16.6 il), correspond to average residence times of about 500 and 25 s, respectively. 

Diamorphine Diamorphine is relatively unstable in aqueous solutions, and minimum decomposition was observed at pH 4. Preparations should be used within 4 weeks when kept at room temperature, but degradation products also have analgesic activity.45,46 Diamorphine is used in the management of opioid dependence this is also a drug of abuse and the overdose is fatal47,48 Interactions are similar to those of opioid analgesics. Withdrawal symptoms of opioid dependence can be treated with diamorphine and methadone.49... 

The kinetics of decomposition of salts for the preparation of ceramic powders reveal the minimum time-temperature conditions necessary for complete decomposition. 

However, when the temperature was raised to 933 K, ankerite decomposition was unaffected by the presence of C02 This afforded an opportunity to separate Reactions (4) and (2) but only in the narrow temperature range between 935 and 975 K (since 975 K was close to the minimum silication temperature). These results indicated that the rates of Equations (2) and (4) were almost identical and thus, if the reaction does proceed in two steps, the rate of (4) is the controlling step at these temperatures. 

---