Components completely miscible in melt only one component crystallizes

A common feature of the cited examples is the decrease in growth rate with dilution. Yet, in one case the glass temperature increases with the concentration of the 

In the example given in Figs. 11.5 and 11.6 the Avrami n remains constant with dilution. However, this is not always the case. There are examples where n increases with addition of the second component,(6) as well as those where it decreases.(12,22) These variations in n apparently reflect changes in the morphology with dilution. 

Two typical examples of the overall crystallization rate, expressed as either fo s or peak time, are given in Fig. 11.7 for poly(ethylene oxide)-poly(vinyl phenol) (18) and for poly(aryl ether ether ketone)-poly(ether imide) (19) in Fig. 11.8. The dependence of the crystallization rates on composition are similar to one another and are closely related to the results for other binary mixtures. The overall crystallization rates follow the pattern established for spherulite growth rates. At the higher crystallization temperatures only a modest decrease in the rate is observed with the addition of the noncrystallizing component However, with a decrease in the crystallization temperature the polymeric diluent becomes more effective in reducing the rate. Because of the retardation in the rate with dilution a much wider range in isothermal crystallization temperatures can be studied. Thus, for the more dilute blends a maximum in the rates with temperature can be observed. This is 

Based on the experimental results that have been described, it is natural to inquire whether the basic theoretical framework that has been developed for the crystallization kinetics of one-component systems can be adapted to polymer mixtures. This question is addressed in the next section. 

In order to examine the role of composition on the spherulite growth rate of the crystallizing component in a miscible blend, and indirectly on the overall crystallization rate, the effect of dilution on each of the terms in the growth rate equation for a one-component system needs to be modified. Consequently, starting with Eq. (9.205) it is found that (23-25) 

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