Polyolefin Spheres from Metallocenes Supported on Noninteracting Polystyrene

Roscoe, Stephen B.; Fréchet, Jean M. J.; Walzer, John F.; Dias, Anthony J.

doi:10.1126/science.280.5361.270

Cited by 134 publications

(71 citation statements)

References 12 publications

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“…The polymerization rates of the three catalysts consist essentially of acceleration to a maximum activity followed by a continuous decline (Figs 3–5). This is consistent with the rate profiles of metallocene/MAO catalysts reported in the literature 41–45. The acceleration phase has been attributed to different induction times of individual catalyst particles caused by inhomogeneous MAO loading,46 and gradual exposure of catalyst sites due to fragmentation of the catalyst particles 47.…”

Section: Resultssupporting

confidence: 90%

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Hammawa

Wanke

2006

Polymer International

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Three catalysts obtained by supporting bis(n‐butylcyclopentadienyl)zirconium dichloride/methylaluminoxane on: (1) porous crosslinked poly(2‐hydroxyethylmethacrylate‐co‐styrene‐co‐divinylbenzene) particles (CAT1); (2) swellable crosslinked poly(styrene‐co‐divinylbenzene) particles (CAT2); and (3) by evaporating the catalyst precursors solution to dry powder, CAT3 were used in gas‐phase polymerization of ethylene, and ethylene/1‐hexene in a 2 L semi‐batch reactor at 80 °C and 1.4 MPa. The average polymerization activities of the three catalysts were 12.3–15.5, 4.2–10.1, and 14.3–62.9 ton PE (mol Zr h)−1 respectively. CAT1 and CAT3 produced polyethylenes with a polydispersity range of 2.3–2.7, while that of CAT2 was 3.5–6.4. The supported catalysts produced polyolefin particles with bulk density of 0.36–0.43 g ml−1, and essentially no fines. Ethylene/1‐hexene co‐polymerization (7 mol m−3 initial 1‐hexene concentration in the reactor) increased polymerization activities and produced lower‐molar‐mass co‐polymers. At 21 mol m−3 1‐hexene the polymerization activities decreased, but the relative amount of the low‐molar‐mass co‐polymer for CAT2 increased, leading to higher polydispersity. Copyright © 2006 Society of Chemical Industry

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Section: Resultssupporting

confidence: 90%

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Hammawa

Wanke

2006

Polymer International

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“…These techniques include time of flight secondary ion mass spectrometry, [13] fluorescence-quenching experiments, [9b, 11] autoradiography, [14] and scanning electron microscopy.…”

Section: Introductionmentioning

confidence: 99%

Visualizing Functional Group Distribution in Solid-Support Beads by Using Optical Analysis

McAlpine

Schreiber

1999

Chem. Eur. J.

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By using optical analysis to visually slice through fluorescently labeled ArgoPore, glass, polystyrene, and Tentagel beads, it is possible to establish where the interior functionalization sites occur within these four resins. By detecting the fluorescence emission of the fluorophore functionalized beads on cross sections of each bead, the position of the dye moieties, and hence the functional-group distribution, are observed. This powerful technique is useful not only in evaluating the polymerization and amino-functionalization processes, processes that are relevant to the reactivity of resins during solid-phase synthesis, it also examines the effective concentration of the functional groups throughout the bead. Thus, this technique will provide information that is useful when predicting resin reactivity and behavior during solid-phase synthesis reactions.

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“…O co-catalisador pode estar presente na fase sólida ou ser adicionado por intermédio de uma fase líquida, juntamente com uma segunda base de Lewis (doador externo) [12][13][14][15] . Os suportes empregados para a manufatura de catalisadores Ziegler-Natta heterogêneos são geralmente a base de MgCl 2 , sílica, alumina ou polímeros [16,17] . Estes materiais, embora inativos para a polimerização, exercem uma influência significativa sobre o desempenho dos catalisadores, aumentando a atividade catalítica ou modificando as propriedades do polímero produzido [1,3,5] .…”

Section: Morfologia Das Partículas De Polímerounclassified

Uma revisão sobre polimerização de olefinas usando catalisadores Ziegler-Natta heterogêneos

Machado

Pinto

2011

Polímeros

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Resumo: A produção em larga escala de materiais poliméricos de elevado interesse industrial, provenientes da polimerização estereoespecífica de olefinas, tornou-se possível depois do advento dos catalisadores Ziegler-Natta. Classificados genericamente em seis gerações, esses catalisadores apresentam diferentes desempenhos em relação ao grau de especificidade do polímero, à atividade e ao controle de morfologia da partícula, o que propicia o desenvolvimento de resinas poliolefínicas com características e propriedades muito variadas. O objetivo principal desse trabalho é revisar e discutir algumas das questões fundamentais que estão relacionadas com as reações de polimerização de olefinas realizadas com catalisadores heterogêneos. Dá-se ênfase particular aos fatores determinantes para a condução apropriada dos processos industriais, como, por exemplo, a fragmentação controlada do catalisador, o fenômeno de replicação das características estruturais do catalisador e o controle da morfologia da partícula de polímero, a importância da prepolimerização e os efeitos relacionados à transferência de calor e massa durante a reação. Discutem-se também aspectos relacionados à modelagem dos sistemas de polimerização e às técnicas experimentais usadas para o estudo do fenômeno de fragmentação das partículas de catalisador. Palavras-chave: Polimerização de olefinas, catalisadores Ziegler-Natta, morfologia das partículas poliméricas, fragmentação catalítica, modelagem. A Survey on Olefins Polymerization Using Heterogeneous Ziegler-Natta CatalystsAbstract: Large-scale production of polymer materials of high industrial value through stereospecific polymerization of olefins became possible only after the advent of Ziegler-Natta catalysts. Usually grouped into six different generations, these catalysts present distinct activity and allow for production of polymer materials with distinct degrees of stereospecificity, morphology and end-use properties. The main objective of this work is to review and discuss some of the fundamental issues related to olefins polymerization reactions performed with heterogeneous catalysts. Particular emphasis is given to factors that affect the performances of real industrial processes, such as the catalyst fragmentation, the control of the final particle morphology and the morphological replication phenomena, the heat and mass transfer limitations during the polymerization reaction and the prepolymerization stage. Aspects related to the modeling of polymerization reactors and to the experimental study of catalyst fragmentation are also discussed. Keywords: Olefins polymerization, Ziegler-Natta catalysts, polymeric particles morphology, catalyst fragmentation, modeling. IntroduçãoO advento dos catalisadores Ziegler-Natta para polimerizar olefinas como o eteno e o propeno representou um grande marco na história dos processos químicos em geral e dos processos de polimerização em particular. A aplicação destes sistemas catalíticos aos processos de polimerização propiciou o controle de características esté...

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Polyolefin Spheres from Metallocenes Supported on Noninteracting Polystyrene

Cited by 134 publications

References 12 publications

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Visualizing Functional Group Distribution in Solid-Support Beads by Using Optical Analysis

Uma revisão sobre polimerização de olefinas usando catalisadores Ziegler-Natta heterogêneos

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