Under specific reaction types calculation

Kinetic approaches represent realistic and comprehensive description of the mechanism of network formation. Under this approach, reaction rates are proportional to the concentration of unreacted functional groups involved in a specific reaction times an associated proportionality constant (the kinetic rate constant). This method can be applied to the examination of different reactor types. It is based on population balances derived from a reaction scheme. An infinite set of mass balance equations will result, one for each polymer chain length present in the reaction system. This leads to ordinary differential or algebraic equations, depending on the reactor type under consideration. This set of equations must be solved to obtain the desired information on polymer distribution, and thus instantaneous and accumulated chain polymer properties can be calculated. In the introductory paragraphs of Section... 

There are a number of caveats. The predictions about the reaction pathway provide many essentials of the sequence of steps and types of interactions that exist among the measured species of the network, but do not provide all of the details of the chemical mechanism. Common chemical knowledge, not used yet on purpose, may supply more details. Furthermore, because not all species in the network were measured, we do not predict the entire pathway but only the part specifically involving the measured species. The fact that the calculation yields a reasonable pathway in the absence of full information is a strength of the analysis. Analyses currently under development are concerned with better estimates of the dependence of variation in one variable on variation in the others and detecting the presence of members of the network that are missing from the time series. 

In practice, it is often not possible to calculate the selectivity for this type of process from first principles. Experimental studies have to be done under various conditions, leading to an empiricd optimum on a small scale. It has been shown in section 5.2.2 that the selectivity can be sensitive to the meso-mixe(hiess, and that these can both decrease on larger scales. It may be practical to study the reaction first in a well mixed semi-batch reactor, preferably equipped with an effective turbine impeller, or propeller. The feed tube should end in the exit flow of the impeller. With this equipment one measures the influence of the feed rate on the selectivity. It may be that a sufficiently high selectivity is obtained when the feeding time has a certain minimum value. The specific energy dissipation should be measured or calculated. 

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