Reaction model for Ziegler-Natta polymerization processes

Böhm, Ludwig

doi:10.1016/0032-3861(78)90280-x

Cited by 78 publications

(25 citation statements)

References 20 publications

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“…The kinetics are so complex for different reasons. In the first place, MgCI,/TiCl, catalysts produce polymers with a rather broad molecular-weight distribution because of the presence of multiple sites in these catalysts, each site type having its own propagation rate constant and chain transfer rate constant (Bohm, 1978). However, measurement of the individual reaction rates on the various types of sites is impossible.…”

Section: Kinetic Modelmentioning

confidence: 99%

Liquid‐phase polymerization of propylene with a highly active catalyst

Samson¹,

Weickert²,

Heerze³

et al. 1998

AIChE Journal

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An experimental setup and a kinetic study of the polymerization of propylene in liquid monomer with a highly active catalyst are presented. The purification system for monomer, the catalyst injection system, the temperature control system, and the polymerization procedures are described in detail. Further, reproducibility of the experiments is tested, the kinetics are described in the temperature range of 27 to 6 7 T , and the influence of prepolymerization in cold liquid propylene is investigated.

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Section: Kinetic Modelmentioning

confidence: 99%

Liquid‐phase polymerization of propylene with a highly active catalyst

Samson¹,

Weickert²,

Heerze³

et al. 1998

AIChE Journal

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“…19 If the active sites remain at the interface of the polymer and the catalyst phase and the polymer grow over the active sites, 57 -59 the firstpolymerized layer would be located on top of the secondpolymerized layer. If the active sites are separated from the catalyst surface and migrate to the polymer/gas phase interface and the polymer grows under the active sites, 60,61 the first-polymerized layer would be found under the second-polymerized layer. If the catalyst phase undergoes significant fragmentation as polymerization occurs, 62 -66 the surface composition of the sequentially polymerized film would have both polymer components, depending on the degree of catalyst fragmentation.…”

Section: Location Of the Active Sites During Polymerizationmentioning

confidence: 99%

Characterization of the Ziegler‐Natta olefin polymerization system: surface science studies on model catalysts

Kim

Somorjai

2001

Surface & Interface Analysis

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Modern surface science techniques have been applied to the heterogeneous Ziegler-Natta catalysis system, polymerizing a-olefins to produce polyolefins, and revealed the correlation between the catalyst surface structure and polymer properties. Two types of thin films -TiCl x /MgCl 2 and TiCl y /Au -were fabricated on an inert gold substrate, using chemical vapor deposition methods, to mimic the high-yield catalysts of MgCl 2 -supported TiCl 4 and TiCl 3 -based catalysts, respectively. Once activated with triethylaluminum (AlEt 3 ) vapor, both catalysts were active for polymerization of ethylene and propylene in the absence of excess AlEt 3 . The model catalyst films were as active as the high-surface-area industrial catalysts. Both catalysts were terminated with chlorine at the surface but had different surface structures. The TiCl x /MgCl 2 film had a distribution of two structures: the dominant sites had the (001) basal plane of these halide crystallites and the minority sites had a non-basal plane structure. The surface of the TiCl y /Au film assumed only the non-basal plane structure. These structural differences resulted in different tacticity of the polypropylene produced with these catalysts. The TiCl x /MgCl 2 catalyst produced both atactic and isotactic polypropylene, whereas the TiCl y catalyst without the MgCl 2 support produced exclusively isotactic polypropylene. The titanium oxidation states did not appear to be an important factor in determining the tacticity of the polypropylene.

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“…Adsorption phenomena are important in most Ziegler-Natta polymerizations, and this requires treatment by heterogeneous kinetics [Bohm, 1978;Boor, 1979;Chien and Ang, 1987;Chien and Hu, 1987;Cooper, 1976;Keii, 1972;Tait and Watkins, 1989] phenomena that are important in the particular reaction system. Consider a Langmuir-Hinschelwood model where reaction occurs only after monomer is adsorbed from solution onto the transition metal active sites.…”

Section: -4i-3 Rate and Degree Of Polymerizationmentioning

confidence: 99%

Stereochemistry of Polymerization

Odian

2004

Principles of Polymerization

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Constitutional (formerly: structural) isomerism is encountered when polymers have the same overall chemical composition (i.e., same molecular formula) but differ in connectivitythe order in which the atoms are connected to each other. Polyacetaldehyde, poly(ethylene oxide), and poly(vinyl alcohol) are constitutional isomers. The first two polymers are CH CH 3 O C H 2 CH OH CH 2 CH 2 O n n Polyacetaldehyde Poly(ethylene oxide) Poly(vinyl alcohol) n obtained from isomeric monomers, acetaldehyde and ethylene oxide. The third is obtained by hydrolysis of poly(vinyl acetate) since vinyl alcohol does not exist (it is the enol form of acetaldehyde). Poly(methyl methacrylate) and poly(ethyl acrylate) are isomeric polymers CH 2 C CH 3 CO 2 CH 3 CH 2 CH CO 2 C 2 H 5 n n Poly (methyl methacrylate) Poly (ethyl acrylate) formed from isomeric monomers. Poly(E-caprolactam) and poly(hexamethylene adipamide) are isomeric even though the monomers are not isomeric. Similarly, the 1 : 1 copolymer of Principles of Polymerization, Fourth Edition.

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Reaction model for Ziegler-Natta polymerization processes

Cited by 78 publications

References 20 publications

Liquid‐phase polymerization of propylene with a highly active catalyst

Liquid‐phase polymerization of propylene with a highly active catalyst

Characterization of the Ziegler‐Natta olefin polymerization system: surface science studies on model catalysts

Stereochemistry of Polymerization

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