Flame product composition

Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

The composition, properties, and size of soot particles collected from flame products vary considerably with flame conditions and growth time. Typically the C—H atomic ratio ranges from two to five and the particles consist of kregular chains or clusters of tiny spheres 10—40 nm in diameter with overall dimensions of perhaps 200 nm, although some may agglomerate further to much larger sizes. 

Each of these dissociation reactions also specifies a definite equilibrium concentration of each product at a given temperature consequently, the reactions are written as equilibrium reactions. In the calculation of the heat of reaction of low-temperature combustion experiments the products could be specified from the chemical stoichiometry but with dissociation, the specification of the product concentrations becomes much more complex and the s in the flame temperature equation [Eq. (1.11)] are as unknown as the flame temperature itself. In order to solve the equation for the n s and T2, it is apparent that one needs more than mass balance equations. The necessary equations are found in the equilibrium relationships that exist among the product composition in the equilibrium system. 

The flame temperature values reported in Fig. 1.3 show some interesting trends. The H/C ratio has a greater effect in rich systems. One can attribute this trend to the fact that there is less nitrogen in the rich cases as well as to a greater effect of the mean specific heat of the combustion products. For richer systems the mean specific heat of the product composition is lower owing to the preponderance of the diatomic molecules CO and H2 in comparison to the triatomic molecules C02 and H20. The diatomic molecules have lower... 

Calculate the flame temperature and product composition of liquid ethylene oxide decomposing at 20 atm by the irreversible reaction... 

The gases enter at 298 K. Calculate the adiabatic flame temperature and the product composition a, b, and c. 

Important products are based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, and foams... 

From equation n. A. 23., it is seen that c depends mainly on conditions in the combustion chamber that is. the flame temperature and combustion product composition through ft and Y. The chamber pressure only indirectly influences c through its effect on T . ... 

No attempt is made, of course, to review aU of chemical thermodynamics. Only those aspects necessary to the proper understanding of the calculation of flame temperature and product composition are reviewed. 

Procedures for calculating the theoretical flame, or product temperature and product composition of a propellant mixture were discussed in the previous section. What remains to be analyzed is the nozzle expansion process. Since most thermochemical performance calculations are made in order to compare various propellants or propellant combinations, certain.ideal assumptions as discussed in Section n. A. are made. These ideal assumptions, however, only relate to the physical processes which actually occur in the rocket motor. As explained, normal dissipative losses such as friction and heat transfer are ignored. The gasses are assumed to enter the nozzle at zero velocity at the temperature and product composition calculated theoretically for the given mixture ratio of the propellant combination. 

D. Flame Vsmperature Calculations 29 TABLE 6 Equilibrium Product Composition of Hydrogen-Oxygen Combustion... 

Figure 5 Product compositions and surface temperatures (upstream and downstream ends) for a 7-mm-Iong, 12-wt%-Pt extruded monolith (400 cells/in. ) at 2 5-sIpm total flow. The H2 and CO sclectivities are lower than those reported in previous experiments because the reactor was not insulated. A heterogeneous steady-state reaction is maintained for rich (> 12%) compositions, while at leaner compositions, a combination of heterogeneous and homogeneous reactions (a blue flame) is observed, with multiple ignited steady-states for compositions between 10 and 12% CH4. (From Ref. 7.)...

The simplest flow systems, namely laminar flow tubes operated at atmospheric pressure, were used in some of the earliest chemical studies of hydrocarbon oxidation [4, 28, 53]. In this type of application, pre-mixed gaseous fuel and air flowed through a heated tube and the products were collected at the outflow under stationary-state conditions. Product compositions were analyzed and extents of reaction were deduced. Even in these earliest studies, the possibility of temperature changes owing to exothermic oxidation were noted and in some cases mildly explosive reaction , probably cool-flames, were detected [4]. 

MAJOR PRODUCT APPLICATIONS flame retarding compositions of polymers hsted below... 

In compiling a list of compositions for colored flame production, formulas have been taken from specifications for certain items and a number of such formulas could be found in a rather unusual source, i.e, a manual on the toxic hazards of pyrotechnic items. Others have come from the writer s notebooks, a few from patent disclosures or from special reports. Since there is now little overlapping between the formulas for ordnance items and for fireworks, the latter, which are appended to the following chapter, arc only of passing interest to the designer of military flares and stars. 

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