"Multiple" nucleation of the (010) contact face of isotactic polypropylene, alpha phase

Crystallization of isotactic polypropylene in its alpha modification (alpha iPP) can be initiated by a variety of nucleating agents. One of its (010) crystallographic planes is made of a highly symmetrical, lozenge shaped arr ay of methyl groups. So far, this plane was known to interact only with sub strates (benzoic acid and its salts, but also polyethylene through its be c ontact face, and polyamides) with a approximate to 5 Angstrom periodicity w hich matches a similar approximate to 5 Angstrom periodicity normal to the short diagonal of the lozenge. In the present investigation, this same loze nge-shaped contact face is shown to interact with nucleating agents with pe riodicities of approximate to 4.2 and approximate to 6.6 Angstrom which mat ch periodicities normal to its long diagonal and to its cell edges, respect ively. Three families of nucleating agents with very different periodicitie s can therefore interact with the same alpha iPP contact plane. (C) 2000 El sevier Science Ltd. All rights reserved.