Weight loss total, kinetics

Kinetics of Total Weight Loss. The method chosen is a simple first order Arrhenius treatment in which a single overall activation energy is utilized. The technique has been applied to the kinetics of the initial weight loss, and therefore, the weight loss values were compared to the maximum weight loss in the entrained flow reactor. 

TABLE VI. Kinetic Parameters for Total Weight Loss... 

In actual experiments we do not usually observe directly the desorbed amount, but rather the derived read-out quantities, as is the time dependence of the pressure in most cases. In a closed system, this pressure is obviously a monotonously increasing function of time. In a flow or pumped system, the pressure-time dependence can exert a maximum, which is a function of the maximum desorption rate, but need not necessarily occur at the same time due to the effect of the pumping speed S. If there are particles on the surface which require different activation energies Ed for their desorption, several maxima (peaks) appear on the time curve of the recorded quantity reflecting the desorption process (total or partial pressure, weight loss). Thereby, the so-called desorption spectrum arises. It is naturally advantageous to evaluate the required kinetic parameters of the desorption processes from the primarily registered read-out curves, particularly from their maxima which are the best defined points. 

The kinetics equations (16) and (18) will allow the calculation of the weight loss rate for the polymer during pyrolysis. However, as previously indicated, the polymer does not consist of molecules with only one degree of polymerization. Therefore, a global kinetics equation for all the polymerization degrees n = 2, 3. 4. . . N should be obtained. For this purpose it is convenient to use the symbol Mo for the total number of polymeric molecules, where... 

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