Macromolecular Reaction Engineering
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Special Series: Polyolefins—Catalyst and Process Innovations
Guest-edited by Joao Soares and Tim McKenna, this series publishes in an on-going fashion invited articles by leading researchers to document the rapid progress in this field.
Condensed Mode Cooling for Ethylene Polymerization: The Influence of the Heat of SorptionArash Alizadeh and Timothy F. L. McKenna*
The relative importance of the higher solubility of n-hexane and its associated heat of sorption on the thermal behavior of the polymer particles during gas phase ethylene polymerization is investigated. It is found that if a polymerizing particle begins to heat-up, the partial desorption of a condensable solute in a gaseous state helps to attenuate the temperature rise in the polymer particles, decreasing the risk of local hot spots.
Macromol. React. Eng. DOI: 10.1002/mren.201300165
Growth Kinetics Obtained from Single Particle Gas-Phase Ethene Homopolymerization with a Ziegler–Natta CatalystLeonhard Mayrhofer and Christian Paulik*
A micro-reactor, equipped with a video microscope is used for studying single particle gas-phase ethylene polymerization. Polymerization conditions are close to industrial set points. A standard 4th generation Ziegler–Natta catalyst system has been used. The rate of polymerization is calculated and related to SEM pictures to allow a deeper understanding of the gas-phase polymerization of ethylene. Different Al/Ti ratios and reaction temperatures are examined and explain the behavior of growing polyethylene-particles in a satisfying way.
Macromol. React. Eng. DOI: 10.1002/mren.201300153
Development of a Hetero-Bimetallic Phillips-Type Catalyst for Ethylene PolymerizationYanning Zeng, Akanksha Matta, Sumant Dwivedi, Toshiaki Taniike, Minoru Terano*
The effects of various second metals in the impregnation solution have been investigated. The polymerization performance in terms of activity and branching is highly depended on the electronegativity of second metal. Bimetallic catalysts containing second metal with low electronegativity improved not only the activity but also the branching ability in ethylene polymerization.
Macromol. React. Eng. DOI: 10.1002/mren.201300119
Ethylene Polymerization Over Ph2C(Cp)(2,7-t-Bu2Flu)ZrCl2 Supported On SiO2-MAOEmilio Casas, Beatriz Paredes, Jose María Escola,* Carlos Martin, Rafael van Grieken
Ethylene polymerization over heterogeneous [Ph2C(Cp)(2,7-t-Bu2Flu)ZrCl2] supported on SiO2-MAO is investigated. At 8 bar, the polyethylenes show molecular weights above 400 000 g ⋅ mol-1. With hydrogen, the activity decreases while with 1-butene, the activity is higher than in the homopolymerization.
Macromol. React. Eng. DOI: 10.1002/mren.201300130
Controlling Polyolefin Properties by In-Reactor Blending: 3. Mechanical PropertiesMartin Ruff,* Reinhold W. Lang, Christian Paulik
The effects of multi-stage (slurry) polymerization on mechanical properties of in-reactor blended UHMW-PE materials is presented, and it is shown that due to a controlled polymerized particle morphology, mechanical properties, such as impact properties can be regulated.
Macromol. React. Eng. DOI: 10.1002/mren.201200077
Analysis of Slurry-Phase Co-Polymerization of Ethylene and 1-Butene by Ziegler–Natta Catalysts Part 1: Experimental Activity ProfilesJohn T. McCoy, Joao B. P. Soares, Randhir Rawatlal*
The activity of Ziegler–Natta catalysts for ethylene polymerization is studied, and a method developed to extract meaningful kinetic parameters from experimental data. Four model parameters are required to reproduce polymerization rate profiles for a range of laboratory experimental conditions.
Macromol. React. Eng. DOI: 10.1002/mren.201200078
Cycloolefin Copolymers by Early and Late Transition Metal Catalysts
Incoronata Tritto,* Laura Boggioni, Andrea Ravasio, Giulia Scalcione
Amorphous alternating E-co-N and E-co-NAC copolymers, in excellent yield, are synthesized with the palladium catalyst 1. N concentration allows for tuning molar mass values. Living E-co-N copolymerization with 2, at 50 °C, allows for efficient synthesis of PE-block-P(E-co-N)s, with crystalline PE and amorphous P(E-co-N) blocks, as well as P(E-co-N)1-block-P(E-co-N)2, with different Tg values.
Macromol. React. Eng. DOI: 10.1002/mren.201200056
Design and Synthesis of Olefin Copolymers with Tunable Amounts of Comonomers Bearing Stabilizing Functionalities
Maria Carmela Sacchi,* Simona Losio, Paola Stagnaro, Stefano Menichetti, Caterina Viglianisi
The present research proposes the design and synthesis of monomers bearing stabilizing functionalities and their copolymerization with ethylene to obtain non-releasing polymeric additives. Such materials can be added to commercial polyolefins to prepare films characterized by stability to auto- and photo-oxidation, with reduced, or eliminated risk, of migration of the stabilizer into the contact food.
Macromol. React. Eng. DOI: 10.1002/mren.201200055
Controlling Polyolefin Properties by In-Reactor Blending: 2. Particle Design
Martin Ruff*, Christian Paulik
Structure properties of in-reactor-blended ultra-high molecular weight polyethylene (UHMW-PE) reactor powders are presented, and it is shown that the particle morphology can be designed by precisely controlled multi-stage (slurry) polymerization. A novel kind of surface structure, named cocoon-structure, of bimodal PE reactor powders from multi-stage polymerizations is presented.
Macromol. React. Eng. DOI: 10.1002/mren.201200050
Controlling Polyolefin Properties by In-Reactor Blending, 1 - Polymerization Process, Precise Kinetics, and Molecular Properties of UHMW-PE PolymersMartin Ruff*, Christian Paulik
A multi-stage polymerization method using a dynamic power-compensating reactor for preparing bimodal PE in-reactor blends is presented. Control of ultrahigh-molecular-weight fractions is achieved by isothermal, isobaric, and isoperibolic steady-state polymerization conditions in a slurry.
Macromol. React. Eng. DOI: 10.1002/mren.201200019
Simultaneous Deconvolution of Molecular Weight and Chemical Composition Distribution of Ethylene/1-Olefin Copolymers: Strategy Validation and ComparisonSiripon Anantawaraskul, Warawut Bongsontia, João B. P. Soares
Four simultaneous deconvolution strategies based on different microstructural information of ethylene/1-olefin copolymers were investigated. Deconvolution based on complete bivariate distribution of molecular weight and chemical composition was found to accurately identify the number of site type and provide best estimated mass fraction and kinetic parameters of each site type.
Macromol. React. Eng. DOI: 10.1002/mren.201100032
Thermodynamic Data of Ethylene-Propane Mixtures in Condensed and Supercritical StateSebastian Kröner, Wang Minjiong, Michael Bartke
Experimental thermodynamic data of the system ethylene/propane in condensed and supercritical state is presented in this work. Experiments and simulations are focused on temperature and pressure conditions relevant for heterogeneous polymerization of polyethylene as applied in industry. Good description of the experimental data could be achieved by simulations using the Peng-Robinson EOS with a liquid phase density correction.
Macromol. React. Eng. DOI: 10.1002/mren.201100014
Bimodality Criterion for the Chemical Composition Distribution of Ethylene/1-Olefin Copolymers: Theoretical Development and Experimental ValidationKanyanut Narkchamnan, Siripon Anantawaraskul,* João B.P. Soares
The bimodality criterion for chemical composition distribution of ethylene/1-olefin copolymers is developed and validated theoretically with simulation data and experimentally with crystallization analysis fractionation (CRYSTAF) and crystallization elution fractionation (CEF). The CCD bimodality criterion derived herein could be useful for determining the appropriate recipe to synthesize copolymer blends with desired CCD characteristics.
Macromol. React. Eng. DOI: 10.1002/mren.201100002
Hard versus Soft Materials as Supports for Metallocene and Post-Metallocene CatalystsCorinna Naundorf, Daniela Ferrari, Giovanni Rojas, Gerhard Fink,* Markus Klapper,* Klaus Müllen
The influence of organic supports on the polymerization behavior of post-metallocene catalysts is studied and compared with similarly supported titanium and zirconium metallocenes. The effects of the immobilization, activation, and polymerization process were studied by video microscopy, laser confocal fluorescence microscopy, SEM, and TEM. A model for the polymerization process for a catalyst supported on latex particles was developed from the results obtained. Organic supports based on latex particles are easily adjustable for different catalysts due to the versatile functionalization of the surfaces and can be applied to different types of olefin polymerization catalysts. They can be considered as an alternative to SiO2 or MgCl2 supports.
Macromol. React. Eng. DOI: 10.1002/mren.200900026
Characteristics of Bimodal Polyethylene Prepared via Co-Immobilization of Chromium and Iron Catalysts on an MgCl2-Based SupportNileshkumar Kukalyekar, Luigi Balzano, Gerrit W. M. Peters, Sanjay Rastogi*, John C. Chadwick*
Bimodal polyethylenes comprising varying proportions of high- and low-molecular-weight fractions are synthesized in a single polymerization stage, via the co-immobilization of a chromium and an iron catalyst on an MgCl2/AlEtn(OEt)3-n support. Changes observed in the viscoelastic response of the polymer melt with increasing content of the high-molecular-weight fraction indicate effective mixing in the bimodal blend. In flow, chains in the high-molecular weight fraction tend to orient and stretch under shear. Due to the longer relaxation time of the high-molecular-weight component, X-ray diffraction and scattering reveal that shear-induced crystallization takes place at temperatures close to the equilibrium melting point of linear polyethylene. The so-crystallized high-molecular-weight component suppresses the nucleation barrier for further crystallization, leading to the formation of a "shish-kebab" polymer morphology.
Macromol. React. Eng. DOI: 10.1002/mren.200900021
Metallocene-Catalyzed Gas-Phase Ethylene Copolymerization: Kinetics and Polymer PropertiesMichiel F. Bergstra*, Günter Weickert, Gerben B. Meier
The influence of 1-hexene is examined on the kinetics of ethylene copolymerization with a metallocene catalyst in gas phase. A model is derived, which is able to describe a large reaction rate increase due to a small amount of incorporated comonomer. This complexation model describes the measured reaction rates for ethylene and 1-hexene, and the co-monomer incorporation. Polymer properties were analyzed, such as comonomer weight fraction. The density, melting point, and molecular weight of the produced polymer decreased with increase in 1-hexene gas concentration. The in situ 1-hexene sorption is estimated and follows Henry's law, but seems much higher than reported in the literature.
Macromol. React. Eng. DOI: 10.1002/mren.200900019
Special Article Series on 'Polyolefins - Catalyst and Process Innovations'John C. Chadwick
This Essay inaugurates a Special Article Series called "Polyolefins - Catalyst and Process Innovations". Examples illustrating recent progress in both the fundamental understanding and application of Ziegler-Natta and single-centre catalysts in polyolefin production are given.
Guest-edited by John C. Chadwick (Dutch Polymer Institute), the new article series will highlight new developments in olefin polymerization catalysis and how increased control over polymer structure and properties can be achieved by catalyst and process modifications.
Macromol. React. Eng. DOI: 10.1002/mren.200900043