Kinetic investigations using rising temperature techniques

Kinetic investigations using rising temperature techniques Since, in general, rates of reaction vary with both a and T, i.e. 

Although there are experimental and interpretative limitations [189, 526] in the kinetic analysis of non-isothermal data, DTA or DSC observations are particularly useful in determining the temperature range of occurrence of one or perhaps a sequence of reactions and also of phase changes including melting. This experimental approach provides, in addition, a useful route to measurements of a in the study of reactions where there is no gas evolution or mass loss. The reliability of conclusions based on non-isothermal data can be increased by quantitatively determining the 

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Nonisothermal reactions Numerous kinetic investigations of the thermal reactions of solids have used rising temperature techniques, often during a linear rate of reactant temperature increase. The kinetic analysis then requires the solution of three equations ... 

Two alternative methods have been used in kinetic investigations of thermal decomposition and, indeed, other reactions of solids in one, yield—time measurements are made while the reactant is maintained at a constant (known) temperature [28] while, in the second, the sample is subjected to a controlled rising temperature [76]. Measurements using both techniques have been widely and variously exploited in the determination of kinetic characteristics and parameters. In the more traditional approach, isothermal studies, the maintenance of a precisely constant temperature throughout the reaction period represents an ideal which cannot be achieved in practice, since a finite time is required to heat the material to reaction temperature. Consequently, the initial segment of the a (fractional decomposition)—time plot cannot refer to isothermal conditions, though the effect of such deviation can be minimized by careful design of equipment. 

It has been shown that a study of crude oil/water interfacial rheology can be used to investigate crude oil emulsion stability and rationalize the effect of chemical demulsifiers. Both kinetic factors relevant to droplet coagulation and the mechanical resistance to coalescence which gives rise to permanent emulsion stability can be studied and defined by these techniques. The effects of crude oil typ e, temperature and aqueous phase changes can be followed and used to pinpoint emulsion problems that may arise in a practical situation. 

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