Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

Pimplapure, Makarand S.; Zheng, Xuejing; Loos, Joachim; Weickert, G.

doi:10.1002/marc.200500144

Cited by 14 publications

(11 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the temperature profile has also been monitored as a sensitive method for the indication of the polymerization rate, 4 besides gravimetric analysis and measurements of the monomer flow.…”

Section: Resultsmentioning

confidence: 99%

Investigations of the initial state polymerization of propylene with Ziegler–Natta catalysts in slurry

Heuvelsland

Wichmann

Schellenberg

2007

J of Applied Polymer Sci

View full text Add to dashboard Cite

ABSTRACT:The initial state polymerization of propylene with Ziegler-Natta catalysts has been investigated and discussed at very low polymerization yields under adiabatic industrial prepolymerization conditions in diluted slurry regarding the effects of significant process parameters like monomer pressure, aluminum alkyl, and donor kind and concentration including the morphology of the catalyst/polymer particles formed. A sharp temperature increase in the first minutes of the initial state polymerization is followed by a temperature maximum and a slow decrease. With cocatalyst triethyl aluminum (TEAL), high prepolymerization yields were already achieved at a molar ratio TEAL/Ti of 3.0, remaining about constant until ratios of at least 300. The external donor dicyclopentyl dimethoxy silane leads to higher polymerization yields than the donor cyclohexyl dimethoxymethyl silane in the initial state polymerization too; however, both show a remarkable decreasing effect on polymerization yield above a specific molar ratio donor/Ti obviously correlated with the bulkiness of the alkyl groups. The particle size of the catalyst and the catalyst/prepolymer particles is increasing with polymerization yield until about 22 g PP/g Cat with particles almost perfectly spherical. The particle size distribution is rather broad at lower prepolymerization stages but unifying with lower polymerization rates at higher polymerization times.

show abstract

Section: Resultsmentioning

confidence: 99%

Investigations of the initial state polymerization of propylene with Ziegler–Natta catalysts in slurry

Heuvelsland

Wichmann

Schellenberg

2007

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…A similar decrease in activity during the first minutes of polymerization, under milder conditions than used here, was reported in the literature. 14 The decrease in activity was attributed to the encapsulating effect of the produced polymer around the active centers in the early stage of polymerization. The polymerrich phase around the active center had a lower monomer concentration than the surrounding me-dium.…”

Section: Resultsmentioning

confidence: 99%

“…5 MgCl 2 -supported TiCl 4 catalysts do not always break up uniformly. Recently, Zheng and coworkers [12][13][14][15] showed that a MgCl 2 -supported TiCl 4 catalyst with a low surface area and porosity and small average pore size breaks up layer by layer. In contrast, a catalyst with a high surface area and porosity and average pore size gives what they called an instantaneous breakup under similar polymerization conditions.…”

Section: Introductionmentioning

confidence: 99%

Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Vestberg

Denifl

Wilén

2008

J of Applied Polymer Sci

View full text Add to dashboard Cite

The effect of the porosity of Ziegler-Natta catalyst particles on early fragmentation, nascent polymer morphology, and activity were studied. The bulk polymerization of propylene was carried out with three different heterogeneous Ziegler-Natta catalysts under industrial conditions at low temperatures, that is, with a novel selfsupported catalyst (A), a SiO 2 -supported catalyst (B), and a MgCl 2 -supported catalyst (C), with triethyl aluminum as a cocatalyst and dicyclopentyl dimethoxy silane as an external donor. The compact catalyst A exhibited no measurable porosity and a very low surface area (<5 m 2 /g) by Brunauer-Emmet-Teller analysis, whereas catalysts B and C showed surface areas of 63 and 250 m 2 /g, respectively. The surface and cross-sectional morphologies of the resulting polymer particles at different stages of particle growth were analyzed by scanning electron microscopy and transmission electron microscopy. The compact catalyst A showed homogeneous and instantaneous fragmentation already in the very early stages of polymerization, which is typically observed for porous MgCl 2 -supported Ziegler-Natta catalysts. Moreover, the compact catalyst particles gave rise to almost perfectly spherical polymer particles with a smooth surface. In contrast, the silicasupported catalyst B gave rise to particles having a cauliflower morphology, and the second reference catalyst C produced fairly spherical polymer particles with a rough surface. All of the three catalysts exhibited similar activities of 450 g of polypropylene/g of catalyst after 30 min of polymerization, and most interestingly, the comparative kinetic data presented indicated that the reaction rates were not influenced by the porosity of the catalyst.

show abstract

“…Detailed information about the polymerization procedure can be found in ref. [2,9,26] In the present study, propylene/ethylene (50:50 v/v) was used in the case of the copolymerization.…”

Section: Polymerization Proceduresmentioning

confidence: 99%

“…[2,3,[7][8][9] A great effort has been made to understand the parameters that influence the catalyst fragmentation process and growth of polyolefins on the surface of heterogeneous catalysts. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Copolymers of propylene with other olefins are important commercial products. However, the understanding of the influence of copolymerization on catalyst fragmentation is far from well known.…”

Section: Introductionmentioning

confidence: 99%

Influence of Copolymerization on Fragmentation Behavior Using Ziegler‐Natta Catalysts

Zheng¹,

Pimplapure²,

Weickert³

et al. 2005

Macromol. Rapid Commun.

Self Cite

View full text Add to dashboard Cite

Summary: A morphological investigation was carried out on different Ziegler‐Natta catalysts during the early stages of propylene homo‐ and propylene‐ethylene copolymerization. For similar polymerization conditions, but dependent on the nature of the catalysts, fragmentation occurs layer‐by‐layer or instantaneously into a large amount of small pieces. However, the incorporation of comonomer ethylene slows down the fragmentation progress. This is believed to be the result of the higher mobility of the just formed propylene‐ethylene copolymer molecules at the active sites.SEM images of the cross‐sectional morphology of polymer particles from catalyst‐I.magnified imageSEM images of the cross‐sectional morphology of polymer particles from catalyst‐I.

show abstract

Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

Cited by 14 publications

References 16 publications

Investigations of the initial state polymerization of propylene with Ziegler–Natta catalysts in slurry

Investigations of the initial state polymerization of propylene with Ziegler–Natta catalysts in slurry

Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Influence of Copolymerization on Fragmentation Behavior Using Ziegler‐Natta Catalysts

Contact Info

Product

Resources

About