Methods involving different heating rates

In this method, data are obtained for reaction proceeding at a series of different heating rates [539,560,561]. This reduces the advantage of the non-isothermal method and one might just as well perform a series of isothermal measurements for which the subsequent analysis will be both more accurate and much simpler. Use of the technique can be illustrated by reference to the work of Ozawa [561] which is quoted as typical. The Doyle equation [eqn. (25)] above can be written 

A plot of log b against should then be linear, where a, is a specified value of a with a slope proportional to E. This approach has been used to 

We terminate this section with reference to a method by Reich [562] in which small and constant temperature steps, AT, were selected and the rate coefficient found by taking the exponent as a constant 

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Method involving more than one thermogram at different heating rates [31—33]... 

Different methods have been investigated for the crystallization of PVA. Most of these methods involve heat treatment to introduce crystallites. The degree of crystallinity, as well as the size of crystallites, depends on the drying conditions. One method involves slow-drying rate dehydration at room temperature under different relative humidities [20-22]. In this process, the amount of polymer in the system is increased and crystallization actually begins late in the process. The effect of drying time on the degree of crystallinity is shown in Fig. 4 where dehydration of the samples was performed with... 

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