Kinetics whole time-course

The time course of the emission intensity is proportional to the concentration of the HEI and, in the case of isolated HEIs, the rate constant for its decomposition is obtained from the CL emission curves. Isothermal kinetic measurements give rise to the activation parameters for the whole transformation and can be used for mechanistic discussion in the case of isolated HEI ° . Specific CL methods have also been used to determine... 

In a reaction under kinetic control, the product composition via transition states T.S.l and T.S.2 is determined by the relative rates of the alternative reactions, which are of course governed by the relative free energies of activation (AG ) of the rate determining step of each reaction (Fig. 1.1). Analysis of product composition over the whole time of the reaction will show a constant ratio. 

A proper fit of the time-courses of some batch reactor experiments at different starting concentrations represents an appropriate test of the rate equation. This implies that numerical integration of the rate equation (e. g. by the Runge Kutta method11121), yielding a simulated time-course, has to fit the data of the measured time-course over the whole range of conversion (compare to Fig. 7-17 B). Examples of these methods will be given after the presentation of the basic kinetic models. 

As ultimate proof of the kinetic model, a fit of time-courses of batch reactor experiments was performed (Fig. 7-21). Initial concentrations of the components over a significant range were chosen to yield hydrolysis conditions (1) and synthesis conditions (2) respectively. Additionally, the equilibrium positions of corresponding experiments A, B and C were chosen to be identical. Figure 7-21 shows a good correlation of calculated and measured data over the whole range of the conversion, for hydrolysis as well as for synthesis. 

Figure 1 Top Whole-cell inward Na+ current (/ni) plotted under baseline (21% O2, solid line) and after 3 min of h fpoxia (dashed line). A scaled inward current is shown (dotted hne). Note that the decrease in current is substantial after 3 min and that the kinetics of the inward current did not change in hypoxia. Bottom Time course of the percentage of initial / a plotted as a function of time. Note the decrease or inhibition of /Na with h3 poxia that starts seconds after the initiation of hypoxia.

Kinetic plots of the different condensation reactions assuming rate laws of first, second, and third order are shown in an exemplary way for linear PPI in Fig. 4. The occurrence of these reaction orders has been observed and explained before [5, 16]. When linear regions appear in these plots, the reaction can be assumed to be of the corresponding order. In most of the cases, a single order of reaction is not sufficient to explain a condensation reaction over the whole course of reaction time. However, different reaction orders can be assigned to different phases of the reaction [5,16]. 

The whole polymerization kinetics has been followed by means of the adiabatic reactor method (3.6). which allows to simultaneously determine polymerization times and rates. In Table V data, related to the overall polymerization time, tp, as well as to the initial and maximum rates of polymerization, are given. All these parameters are, of course, very relevant to RIM technology. 

We cannot exclude that in the course of time this approach will become dominant and consistent theoretical models will help us to avoid the temptation to adjust the whole set of kinetic parameters as soon as some new experimental curve appears. However, the remaining problems are still tremendous and require serious effort some of them will be discussed more thoroughly in Section III.B. Nevertheless, several publications reflect the results already obtained via this way (see, e.g., Green, 2001 Zabamick, 2005). 

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