STUDIES OF DIFFUSION IN POLYMERS BY ULTRAVIOLET MICROSCOPY .2. DIFFUSION OF ATACTIC FRACTIONS IN ISOTACTIC POLYPROPYLENE

Ultraviolet (u.v.) absorbing and fluorescent labels have been attached to isotactic and atactic polypropylene by reaction with appropriate sulphonyl azides. The distribution is random and substitution does not affect the crystallization. The labelled polymer can be visualized by u.v. absorption or fluorescence microscopy. By monitoring penetration of isotactic polymer by labelled atactic, the diffusion coefficient of the atactic polymer has been determined over a range of temperatures. The redistribution of atactic polymer during growth of spherulites of isotactic polymer has been studied. Atactic polymer behaves quite differently to small additive molecules. The fibrosity of polypropylene spherulites is associated with rejection of atactic polymer from crystallizing regions. There is significant non-uniformity of atactic content between the spherulite centres and the boundaries. © 1990.