Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst

2001 ◽  
Vol 81 (4) ◽  
pp. 1035-1047 ◽  
Author(s):  
Fumihiko Shimizu ◽  
Jochem T. M. Pater ◽  
G�nter Weickert
Keyword(s):  
Molecular Weight ◽  
Time Dependency ◽  
Natta Catalyst ◽  
Liquid Propylene ◽  
Ziegler Natta Catalyst

scholarly journals Multiplicity of Active-Site in Heterogeneous Ziegler-Natta Catalyst and Its Correlation with Polymer Microstructure

1970 ◽  
Vol 46 (4) ◽  
pp. 487-494
Author(s):  
ATM Kamrul Hasan
Keyword(s):  
Molecular Weight ◽  
Computer Simulation ◽  
Active Site ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chain Structure ◽  
Surface Complexes ◽  
Polymer Microstructure ◽  
Natta Catalyst ◽  
Ziegler Natta Catalyst

Multiplicity of active-site in heterogeneous Ziegler-Natta catalysts and its correlation with polymer microstructure was studied through the surface structure analysis of catalyst by computer simulation of X-ray Photoelectron Spectroscopy (XPS) data and microstructure investigation of polypropylene chains based on the deconvolution of the molecular weight distribution curves by multiple Flory most probable distributions using Gel Permeation Chromatography (GPC) method. The number and relative intensities of these peaks were found correlated to the distribution of multiple active sites. In this investigation, four individual categories of active sites were identified, each of which yields polypropylene with unique properties of molecular weight and chain structure different from other active sites. The reason of the multiplicity of active sites was determined by the presence of different locations of surface titanium species coordinated with other surface atoms or molecules. These different surface complexes of active species determine the multiple active site nature of catalyst which replicates the microtacticity, molecular weight and chain microstructure distribution of polymer. Keywords: Ziegler-Natta catalyst; Multiple active sites; Flory components; Computer simulation; Deconvolution; MWD. DOI: http://dx.doi.org/10.3329/bjsir.v46i4.9596 BJSIR 2011; 46(4): 487-494

scholarly journals Modeling of Ethylene Polymerization with Ziegler-Natta Catalyst in a Bubbling Fluidized Bed Reactor

2021 ◽  
Author(s):  
Neda Felorzabihi
Keyword(s):  
Molecular Weight ◽  
Kinetic Model ◽  
Fluidized Bed ◽  
Ethylene Polymerization ◽  
Fluidized Bed Reactor ◽  
Polymerization Reaction ◽  
Solid Catalyst ◽  
Gas Temperature ◽  
Natta Catalyst ◽  
Ziegler Natta Catalyst

In the present study, a new dynamic fluidized bed reactor (FBR) model is developed to account for the effect of bubble growth in the bed height on the dynamic behaviour of the reactor and the molecular properties of the polymer product. The model takes into account the existence of solid catalyst in both phases and consequently, the occurrence of polymerization reaction in both bubble and emulsion phases. A dynamic two-phase model is employed for predicting the key hydrodynamic parameters of the bed. A comprehensive kinetic model for ethylene polymerization in the presence of multiple-site Ziegler-Natta catalyst is considered to describe the number and molecular weight averages and molecular weight distribution of polymer in the FBR. The hydrodynamic model and the kinetic model have been coupled and solved simultaneously to simulate the performance of the fluidized bed reactor. The study incorporates the effects of the most important reactor parameters such as superficial gas velocity, mean particle size, inlet gas temperature, bubble size, recycle stream and chain transfer agent on the steady-state behaviour of the FBR. The proposed dynamic model is capable of predicting both the performance of the reactor and the polymer physiochemical properties.

Less Entangled Ultrahigh-Molecular-Weight Polyethylene Produced by Nano-Dispersed Ziegler–Natta Catalyst

2021 ◽  
Vol 60 (7) ◽  
pp. 2818-2827
Author(s):  
Patchanee Chammingkwan ◽  
Yusuke Bando ◽  
Le Thi Tuyet Mai ◽  
Toru Wada ◽  
Ashutosh Thakur ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Ultrahigh Molecular Weight ◽  
Natta Catalyst ◽  
Ziegler Natta Catalyst
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