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High impact polypropylene: Morphology generation during homo-stage

Poster presented at 12th International Workshop on Polymer Reaction Engineering, 17. - 20. Mai 2016, University of Hamburg, Germany
: Plata, Miguel; Bartke, Michael

2016, 1 Folie
International Workshop on Polymer Reaction Engineering <12, 2016, Hamburg>
Fraunhofer IAP ()
Anfrage beim Institut / Available on request from the institute

Heterophasic propylene copolymers (Hecoss) are versatile polymeric materials used in various applications such as automotive, packaging, construction industry among others. Heterophasic propylene copolymers consist of two main components: a polymer matrix of isotactic polypropylene and a dispersed rubbery ethylene-propylene copolymer, which is not miscible into the matrix phase. While the matrix improves stiffness, the elastomeric phase enhances the impact strength and the mechanical behavior at low temperature. Heterophasic propylene copolymers are produced in -at-least- two stage processes. In the first stage, starting from the catalyst particle, the homopolymer matrix is build, in the second stage, ethylene-propylene-rubber is polymerized into the polymer particle. The morphology of hiPP particles is of great interest for a number of reasons since the quantity of EPR, as well as the size and distribution of the rubber domains within the particles will have a great influence on the final properties of the polymer. Since the rubber formed in the second stage is sticky, rubber formation on the outer surface of the particle might lead to particle agglomeration and subsequent operational problems. Providing sufficient porosity for rubber accommodation in the heco-stage is one key element for avoiding these operational issues. Furthermore, particle morphology influences heat- and mass transfer within the polymer particles and therefore has an impact on reaction conditions at the active sites of the catalyst. The current contribution deals with the the effect of reaction conditions, in particular prepolymerization conditions, on resulting particle morphology and how the matrix particle morphology influences rubber incorporation in the heco-stage. Matrix polymerization in both bulk and gas-phase polymerization followed by a gas-phase polymerization of the rubber are discussed for two different Ziegler-Natta catalysts. The resulting particle morphology, transport properties and process kinetics are presented and compared. This research forms part of the research programme of the Dutch Polymer Institute (DPI), project 785.