Effect of Cocrystallization

Cocrystallization during Crystaf analysis can be investigated by comparing experimental Crystaf profiles of blends with their predicted Crystaf profiles, assuming the absence of cocrystallization. The Crystaf profiles of the blends in the absence of cocrystallization can be estimated as the summation of the Crystaf profiles of each parent sample, measured alone, multiplied by its weight fraction in the blend. Deviations from the predicted profile are a measure of the extent of co crystallization taking place during the analysis. 

When a blend is made of polymers with very different crystallizabili-ties, CO crystallization is minimal and does not have a significant effect on Crystaf profiles [1,65,66]. However, cocrystallization can be significant when the components of the blend have similar crystallizabilities [67]. In this case, cocrystallization can be so dramatic as to distort the shape of the measured Crystaf profile for the blend and completely mislead its interpretation. 

In our recent work [67], we investigated the effect of comonomer type on CO crystallization using a series of ethylene/1-olefin copolymers with four comonomer types propylene, 1-hexene, 1-octene, and 1-dodecene. Four blends, one for each copolymer type, were prepared such that they crystallized at the same temperature range and had similar ATq to ehminate the effect of similarity of chain crystalHzabihties. The Crystaf results of these blends indicated that the comonomer type of the parent samples did not appreciably influence their cocrystalHzation behavior, as illustrated in Fig. 39. 

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Miyata and Takemoto found that deoxycholic acid (DCA) and apocholic acid could be used as host molecules for inclusion polymerization of butadienes [75-83]. They reported the living nature of the polymerization, the effects of cocrystallized agents on the yields, and the increase in melting temperature after polymerization. In DCA, polybutadiene was over 25% 1,2... 

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