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Fragmentation of Ziegler-Natta Catalyst Particles During Propylene Polymerization

✍ Scribed by Mohammed Abboud; Peter Denifl; Karl-Heinz Reichert

Publisher
John Wiley and Sons
Year
2005
Tongue
English
Weight
215 KB
Volume
290
Category
Article
ISSN
1438-7492

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✦ Synopsis

Abstract

Summary: Analyzing polymer particles by microscopy technique at different polymerization times provided information regarding the catalyst support break‐up rate and degree of fragmentation during polymerization. Polymer samples were prepared at different polymerization times and melted under a video microscope to track the progress of fragmentation. Studies focused on effect of the catalyst support on the process and degree of catalyst fragmentation. Fragmentation behaviors of both a catalyst without an external support and a silica supported Ziegler‐Natta catalyst were compared. Fragmentation of catalyst was observed to occur in the whole catalyst matrix at the very beginning of polymerization. In the case of the catalyst without an external support, fragmentation was faster and more uniform than that of the silica supported catalyst. Results corresponded to the activity distribution of single catalyst particles as determined by video microscopy. The catalyst without an external support having particles of similar activities showed similar degrees of fragmentation. Conversely, silica supported catalyst having particles of different growth behavior produced particles having different degrees of fragmentation. The rate of increase in the number of catalyst fragments and their surface area with time during polymerization was investigated. Results correlated the catalyst activation period during the initial stage of polymerization to catalyst fragmentation.

Poly(propylene) particles produced with silica supported (upper image) and non‐supported (lower image) Ziegler‐Natta catalysts.

magnified imagePoly(propylene) particles produced with silica supported (upper image) and non‐supported (lower image) Ziegler‐Natta catalysts.

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