Effects of the catalyst system on the crystallization of polypropylene*

In search of a better understanding of catalyst effects on final product qualities of polypropylene, an attempt was made to establish a correlation between catalyst type, polymer chain structure of homopolymers, crystallization behavior, as well as final morphology and mechanical properties. Conventional Ziegler–Natta catalyst systems as well as novel metallocene catalysts were investigated, and influences of molar mass distribution and chain regularity were investigated as separate factors. Metallocene-based isotactic polypropylene shows some special effects regarding the nucleation density and the correlation between stereoregularity and mechanics that do not fit into the general picture for Ziegler–Natta catalyst based products. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2507–2515, 1999