Spherulites polyepichlorohydrin

Figure 1. Polyepichlorohydrin spherulites. Left Type I spherulites from 329C after melting at 170°C and crystallizing at 50°C for 185 min. (128x). Right Type 11 spherulites from 39A after melting at 150°C and crystallizing at 30°C for 222 min. (128x).

Spherulite Morphology. Crystalline polyepichlorohydrin readily forms spherulites on cooling from the melt. As shown in Figure 1, we have observed two kinds of spherulites. 

Overall crystallization rate of blends of "fast" and "slow" crystallizing polymers. We obtained further evidence that the greater ease of nucleation of optically active polymer into Type II spherulites is responsible for the observed increase in crystallization rate by studying solution blends of 2413 and a nonopt-ically active polyepichlorohydrin. We found that addition of only 6% of 2413 reduced the ti at 50"C of the blow" polymer from 32 min to less than 10 min. 

The results of this study further reveal that the crystalline polyepichlorohydrin we have studied consists of isotactic sequences that can crystallize in the form of two different kinds of spherulites. We have shown that the two kinds of spherulites can cocrystallize- At present our educated guess is that all the polymers we have examined contain either Type I or a mixture of Type I and Type II spherulites in varying proportions. The polymers that crystallize most rapidly and that have the highest melting temperatures have some optical activity and their films contain predominantly Type II spherulites. We conclude that the Type II spherulites are obtained from optically active polymer sequences. We do not mean to imply that all sequences in these... 

In fact, there is a direct parallel to some of our findings reported in the case of crystalline polypropyleneoxide, which is structurally the same as polyepichlorohydrin except that the chlorine atom on the pendant methylene substituent is replaced by a hydrogen atom. Two kinds of spherulites have been observed in crystalline polypropyleneoxide (14). The two were not shown to cocrystallize. 

The purposes of this study were to determine what chemical and physical structures are present in polyepichlorohydrin and to correlate these structures with the crystallization rates observed microscopically and dilatometrically. Crystallization rates were shown to be an extremely sensitive way of characterizing these polymers. For example, the study revealed that the crystalline polyepichlorohydrins examined consisted of isotactic sequences that can crystallize as two different kinds of spheru-lites, arbitrarily called Type I and Type II. The two types can cocrystallize. The polymers that crystallize most rapidly and that have the highest melting temperature have some optical activity. Their films contain predominantly Type II spherulites. Polymers that contain Type I spherulites melt lower and show little or no optical activity. These polymers are racemic mixtures. 

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