Advances in Ziegler‐Natta polymerization ‐ unique polyolefin copolymers, alloys and blends made directly in the reactor

Galli, Paolo; Haylock, J. C.

doi:10.1002/masy.19920630106

Cited by 79 publications

(8 citation statements)

References 28 publications

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“…As propylene polymerization proceeded from 0 to 3 min, the spherical shape of the catalyst particles was well preserved. Similar phenomena have been well reported in the past [ 42 , 43 , 44 , 45 , 46 ]. After only 30 s of polymerization, the particle’s outer surface looked like a mixture of tiny irregular polymer particles and large (1 to 2 µm) grains with smooth surfaces.…”

Section: Resultssupporting

confidence: 91%

Comparative Study on Kinetics of Ethylene and Propylene Polymerizations with Supported Ziegler–Natta Catalyst: Catalyst Fragmentation Promoted by Polymer Crystalline Lamellae

Zhang

Jiang

et al. 2019

Polymers

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The kinetic behaviors of ethylene and propylene polymerizations with the same MgCl2-supported Ziegler–Natta (Z–N) catalyst containing an internal electron donor were compared. Changes of polymerization activity and active center concentration ([C*]) with time in the first 10 min were determined. Activity of ethylene polymerization was only 25% of that of propylene, and the polymerization rate (Rp) quickly decayed with time (tp) in the former system, in contrast to stable Rp in the latter. The ethylene system showed a very low [C*]/[Ti] ratio (<0.6%), in contrast to a much higher [C*]/[Ti] ratio (1.5%–4.9%) in propylene polymerization. The two systems showed noticeably different morphologies of the nascent polymer/catalyst particles, with the PP/catalyst particles being more compact and homogeneous than the PE/catalyst particles. The different kinetic behaviors of the two systems were explained by faster and more sufficient catalyst fragmentation in propylene polymerization than the ethylene system. The smaller lamellar thickness (<20 nm) in nascent polypropylene compared with the size of nanopores (15–25 nm) in the catalyst was considered the key factor for efficient catalyst fragmentation in propylene polymerization, as the PP lamellae may grow inside the nanopores and break up the catalyst particles.

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Section: Resultssupporting

confidence: 91%

Comparative Study on Kinetics of Ethylene and Propylene Polymerizations with Supported Ziegler–Natta Catalyst: Catalyst Fragmentation Promoted by Polymer Crystalline Lamellae

Zhang

Jiang

et al. 2019

Polymers

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“…Good replication is supposed to occur when there is an adequate balance between the mechanical strength of the particle and catalytic activity. Replication factors of 40-50 (ratio of average polymer particle diameter to average catalyst particle diameter) are obtained with third generation Ziegler-Natta catalysts (Galli and Haylock, 1992). For the case of continuous reactors, residence time distribution can significantly affect this particle size distribution (Soares and Hamielec, 1995d;Choi et al, 1994).…”

Section: Model Development: Olefin Polymerization With Homogeneous An...mentioning

confidence: 99%

Mathematical Modeling of Multicomponent Chain-Growth Polymerizations in Batch, Semibatch, and Continuous Reactors: A Review

Dubé

Soares

Penlidis

et al. 1997

Ind. Eng. Chem. Res.

182

122

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A practical methodology for the computer modeling of multicomponent chain-growth polymerizations, namely, free-radical and ionic systems, has been developed. This is an extension of a paper by Hamielec, MacGregor, and Penlidis (Multicomponent free-radical polymerization in batch, semi-batch and continuous reactors. Makromol. Chem., Macromol. Symp. 1987, 10/ 11, 521). The approach is general, providing a common model framework which is applicable to many multicomponent systems. Model calculations include conversion of the monomers, multivariable distributions of concentrations of monomers bound in the polymer chains and molecular weights, long- and short-chain branching frequencies, chain microstructure, and cross-linked gel content when applicable. Diffusion-controlled termination, propagation, and initiation reactions are accounted for using the free-volume theory. When necessary, chain-length-dependent diffusion-controlled termination may be employed. Various comonomer systems are used to illustrate the development of practical semibatch and continuous reactor operational policies for the manufacture of copolymers with high quality and productivity. These comprehensive polymerization models may be used by scientists and engineers to reduce the time required to develop new polymer products and advanced production processes for their manufacture as well as to optimize existing processes.

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“…33−36 Other methods aimed at improving dispersion are the addition during polymerization to form an in-reactor compound of iPP/ nucleating agent 50−52 or using them as a support of a single-site metallocene catalyst. 51,53 We have recently reported a different strategy for introducing nucleating agents during polymerization and forming an inreactor compound of iPP/nucleating agent, 54 exploiting the opportunities offered by the reactor granule technology (RGT) 2,55,56 to polymerize other monomers different from propene in a prepolymerization stage. In this controlled process, olefinic monomers are prepolymerized on the MgCl 2 -supported catalyst, giving a porous spherical granule that acts as a microreactor for the subsequent polymerization of other monomers to obtain a polyolefin alloy.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In this controlled process, olefinic monomers are prepolymerized on the MgCl 2 -supported catalyst, giving a porous spherical granule that acts as a microreactor for the subsequent polymerization of other monomers to obtain a polyolefin alloy. 55 In the prepolymerization step, generally, propene is polymerized to produce porous particles of iPP and other monomers are polymerized within the solid particles. A polypropylene skin encloses the second polymer phase (generally an amorphous rubbery or low-melting material), thereby preventing coalescence of particles.…”

Section: ■ Introductionmentioning

confidence: 99%

The “Nodular” α Form of Isotactic Polypropylene: Stiff and Strong Polypropylene with High Deformability

et al. 2017

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A study of the nucleating effects of isotactic poly(trimethylallylsilane) (iPTMAS) and poly(vinylcyclohexane) (iPVCH) for isotactic polypropylene (iPP) and their influence on the mechanical behavior of iPP is reported. The particles of catalyst are covered by poly(trimethylallylsilane) or poly(vinylcyclohexane) by polymerization of the corresponding monomers before polymerization of propylene. The method guarantees that the nucleating agents are perfectly dispersed into the iPP samples, with their consequent high efficiency. Isotactic poly(vinylcyclohexane) and poly(trimethylallylsilane) favor crystallization from the melt of α and β forms, respectively. Both nucleating agents affect the morphology greatly reducing the size of shperulites. This in turn affects the mechanical properties improving ductility and flexibility. All nucleated samples crystallize by rapid cooling from the melt in the α form and not in the mesophase, as occurs in the pure iPP. The resulting α form presents nodular crystals and behaves as a stiff material with high deformability.

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Advances in Ziegler‐Natta polymerization ‐ unique polyolefin copolymers, alloys and blends made directly in the reactor

Cited by 79 publications

References 28 publications

Comparative Study on Kinetics of Ethylene and Propylene Polymerizations with Supported Ziegler–Natta Catalyst: Catalyst Fragmentation Promoted by Polymer Crystalline Lamellae

Comparative Study on Kinetics of Ethylene and Propylene Polymerizations with Supported Ziegler–Natta Catalyst: Catalyst Fragmentation Promoted by Polymer Crystalline Lamellae

Mathematical Modeling of Multicomponent Chain-Growth Polymerizations in Batch, Semibatch, and Continuous Reactors: A Review

The “Nodular” α Form of Isotactic Polypropylene: Stiff and Strong Polypropylene with High Deformability

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