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Ozawa index

Fig. 10.31 Illustration of the Ozawa method to treat (a) several DSC curves with various cooling rates a. (b) A group of crystallinity data Xc are read at a constant temperature, then (c) the Ozawa index can be obtained from the slope of lg[—ln(l — X )] versus lg(a)... Fig. 10.31 Illustration of the Ozawa method to treat (a) several DSC curves with various cooling rates a. (b) A group of crystallinity data Xc are read at a constant temperature, then (c) the Ozawa index can be obtained from the slope of lg[—ln(l — X )] versus lg(a)...
Here, q is called the Ozawa index. Corresponding to one-dimensional growth, q = 2 two-dimensional growth, q = 3 and three-dimensional growth, = 4. In practical measurements, one may determine the values of crystallinity XJa) at a constant temperature from a series of DSC crystallization curve with various cooling rates a, and then plot lg[—ln(l—X )] versus lg(a), to obtain the Ozawa index directly from the slope, as illustrated in Fig. 10.31a-c. [Pg.218]

As a matter of fact, the above approach based on the changes in Avrami index or Ozawa index to obtain the information about the changes of crystal nucleation modes and of crystal growth dimension, is a scaling analysis to the time evolutimi of crystal morphology from the phenomenological point of view. The similar scaling analysis has also been widely applied in the other areas of polymer physics. [Pg.219]

Accordingly, on a series of crystallinity versus time curves (see Fig. 10.31b), one can take the data points along the horizontal equal-crystallinity line, and then obtain the ratios of the Avrami indexes and the rate constants separately from the slope and the intercept of log(fl) versus log(f)- The experiments have verified that a better linear relationship can be obtained in comparing this approach to the conventional Ozawa method. [Pg.219]

Usually the TG curve should be determined at a slow heating rate, and E was estimated for low conversion (say mass loss 5%) by using the Ozawa-Flynn-Wall method. If we assume t( = 20 000h, Tf equals the thermal index of the material. With the use of higher temperatures, the shorter is the lifetime, as shown in Figure 5.1. [Pg.131]


See other pages where Ozawa index is mentioned: [Pg.29]   
See also in sourсe #XX -- [ Pg.218 ]




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