Vapor-phase reactions combustion

Vanadium-Sodium Compounds Most Corrosive. Physical property data for vanadates, phase diagrams, laboratory experiments, and numerous field investigations have shown that the sodium vanadates are the lowest melting compounds and are the most corrosive to metals and refractories. These compounds are thought to form by either the vapor phase reaction of NaCI and V2O5 or by the combination of fine droplets of these materials upon the cooler parts of combustion equipment. 

Consider possible vapor-phase reactions. These might include combustion reactions, other vapor-phase reactions such as the reaction of organic vapors with a chlorine atmosphere, and vapor-phase decomposition of materials such as ethylene oxide or organic peroxide. 

Free Radical Trap Theories. Combustion vapor-phase reactions have been studied using premixed gas flames such as methane. Considerable information concerning the mechanism of flame propagation has resulted from this work 40, 49, 50). Basically the process occurs predominantly by branching chain reactions among free radicals. The major chain branching reactions are... 

CHEMICAL PROPERTIES combustible solid can react vigorously with strong oxidizing agents heat may contribute to instability will degrade in the atmosphere by the vapor-phase reaction with photochemically produced hydroxyl radicals with an estimated half-life of about 8 days FP (200°C, 392°F) LFL/UFL (NA) AT (none to boiling point). 

A reaction system which is not occurred in an isothermal condition and able to show chemical oscillations is driven by temperature changes that have significance for chemists in order to process controls and designing a reaction. Periodicity in such chemical oscillators which is certainly evolved by thermal changes has been investigated by several researchers especially in hydrocarbon fuels and their combustion derivatives [25]. A detailed theoretical and practical validation of those oscillating combustion reactions has also been reported in chlorination of CH3CI in vapor-phase reaction [26]. 

Combustion of polymeric materials involves a complex process, where both condensed and vapor-phase reactions occur at exposed surfaces that are sources of flame and/or thermal radiation of the most common parameters measuring the flammability of polymeric materials are heat release rate (HRR) and mass loss rate (MLR) from cone calorimetry. Recently, nanocomposites containing nanoparticles have been of great interest in the composite industries. In particular, polymer blends containing clays have not been comprehensively studied for their flammability, in spite of the fact that most plastic products are made out of blends of more than two polymer. Furthermore, because the dispersion of nanoparticles is a key factor in determining the HRR and MLR of nanocomposites [23-26], we investigated correlations between flammability and dispersion in air and under nitrogen, especially for polymer blends. 

As mentioned, the addition of a small amount of water to the bomb ensures that the vapor phase remains saturated throughout the experiment, so that liquid water is produced in the combustion reaction. It also ensures that the mixture of nitric oxides formed by the oxidation of the N2 will be converted to NOjT(aq), which is simple to determine. 

Table 9.1 and Fig. 9.11 also depict vaporization temperatures of the metals in each product composition and give a graphical representation of Glassman s criterion. When Vvo (or Td, as the case dictates) of the refractory compound formed is greater than the vaporization temperature, Tb, of the metal reactant, small metal particles will vaporize during combustion and bum in the vapor phase. When the contra condition holds, much slower surface reactions will... 

The process employs the supercritical fluid carbon dioxide as a solvent. When a compound (in this case carbon dioxide) is subjected to temperatures and pressures above its critical point (31°C, 7.4 MPa, respectively), it exhibits properties that differ from both the liquid and vapor phases. Polar bonding between molecules essentially stops. Some organic compounds that are normally insoluble become completely soluble (miscible in all proportions) in supercritical fluids. Supercritical carbon dioxide sustains combustion and oxidation reactions because it mixes well with oxygen and with nonpolar organic compounds. 

In addition to aerosol age, phosphorus aerosol speciation is also affected by the humidity of the ambient environment (Van Voris et al. 1987). Washout and rainout processes transport both the reaction products of vapor phase phosphorus and unreacted particles of phosphorus to water and land (Berkowitz et al. 1981). Because of its lower water solubility, physical state (gas), and slower reactivity, phosphine formed during the combustion of white phosphorus or released to the atmosphere from other media persists in the atmosphere longer than other reaction products. 

AHj is the combustion enthalpy, is the maximum gas-phase reaction rate, 5j, 5, and 5 are, respectively, the thickness of the hot layer, heated polymer layer and half-thickness of the reaction zone in the flame a is the angle of inclination of the reaction zone to the polymer surface AHo = cT -h Yp AH is the heat necessary for polymer gasification and heating of combustible vapors. 

Chemical Vapor Deposition (CVD) has been defined as a materials synthesis process whereby constituents of the vapor phase react chemically near or on a substrate surface to form a solid product. With these traditional processes a reaction chamber and secondary energy (heat) source are mandatory making them different from the Combustion CVD process. Numerous flame-based variations of CVD have been used to generate powders, perform spray pyrolysis, create glass forms, and form carbon films including diamond films. 

Flame-retardant styrenic polymers find utility in applications such as building insulation (expanded polystyrene foam) and electronic enclosures (flame-retardant HIPS, ABS and styrenic blends). The most effective flame retardants are halogen-(particularly bromine)-containing compounds these flame retardants act by inhibiting the radical combustion reactions occurring in the vapor phase. Flame-retardant plastics are in a state of flux, due to influences of... 

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