On the development of special positive isotactic polypropylene spherulites

Abstract

A new type of positive α-iPP spherulites has been developed by self-seeding process. The growth process of these positive α-iPP spherulites is just like "photographic development process," which is very different from the conventional growth process of polymer spherulites. Scanning electron microscopy (SEM) was used to explore the morphologies of these positive α-iPP spherulites on a lamellar level. The results show that these spherulites are composed of a large number of lamellae having interwoven structures, which result in different optical character, special melting behavior, and different contrast under SEM as compared with the conventional meltcrystallized spherulites. The development of these interwoven lamellar structures has been considered because in the sites of the original spherulites, a large number of self-nuclei are formed because of the incomplete melting of the original spherulites and these induce nearly equal number of radial and tangential lamellae at rather high temperatures. © 2006 Wiley Periodicals, Inc.