Studies of structural composition distribution heterogeneity in ethylene/1-hexene copolymers using thermal fractionation technique (SSA)

Białek, Marzena; Czaja, Krystyna; Sacher-Majewska, Beata

doi:10.1016/j.tca.2005.03.011

Cited by 28 publications

(33 citation statements)

References 22 publications

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“…Note that in SSA fractionation, the polymer undergoes multiple alternate melting and crystallization processes (without physical separation of the chains) as the temperature decreases. Therefore, it is sensitive to linear and uninterrupted chain sequences; hence to both intra-and inter-chain defects [26][27][28][29][30][31]. The 13 C NMR results, reported earlier, complement this remark.…”

Section: Thermal Behavior Of the As-synthesized Polyethylenesmentioning

confidence: 59%

“…The synthesized copolymers were thermally fractionated using the above DSC instrument, and following the successive selfnucleation and annealing (SSA) experimental procedure reported in the literature [26][27][28][29][30][31][32]. Seven annealing steps (160, 125, 119, 114, 111, 107, and 103°C) were applied.…”

Section: Thermal Properties Density and Copolymer Melt Fractionationmentioning

confidence: 99%

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Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Adamu

Atiqullah

Malaibari

et al. 2016

Journal of the Taiwan Institute of Chemical Engineers

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Keywords:Metallocene catalyst Pseudo-homogeneous and in-situ heterogeneous isomeric ethylene−α-olefin copolymerization Hydrodynamic boundary layer mass transfer Inter-and intra-chain backbone composition distribution Lamellar thickness distribution Thermal properties a b s t r a c t This study reports a novel conceptual framework that can be easily experimented to evaluate the effects of hydrodynamic boundary layer mass transfer, methylaluminoxane (MAO) anion design, and comonomer steric hindrance on metallocene-catalyzed ethylene polymerization. This approach was illustrated by conducting homo-and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride ( n BuCp) 2 ZrCl 2 , using (i) MAO anion 1 (unsupported [MAOCl 2 ] − ) and pseudo-homogeneous reference polymerization, and (ii) MAO anion 2 (supported Si−O−[MAOCl 2 ] − ) and in-situ heterogeneous polymerization. The measured polymer morphology, catalyst productivity, molecular weight distribution, and inter-chain composition distribution were related to the locus of polymerization, comonomer effect, in-situ chain transfer process, and micromixing effect, respectively. The peak melting and crystallization temperatures and %crystallinity were mathematically correlated to the parameters of microstructural composition distributions, melt fractionation temperatures, and average lamellar thickness. These relations showed to be insightful. The comonomer-induced enchainment defects and the eventual partial disruption of the crystal lattice were successfully modeled using Flory and GibbsThompson equations. The present methodology can also be applied to study ethylene−α-olefin copolymerization, performed using MAO-activated non-metallocene precatalysts.

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Section: Thermal Behavior Of the As-synthesized Polyethylenesmentioning

confidence: 59%

Section: Thermal Properties Density and Copolymer Melt Fractionationmentioning

confidence: 99%

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Adamu

Atiqullah

Malaibari

et al. 2016

Journal of the Taiwan Institute of Chemical Engineers

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“…Nowadays many researchers study the influence of metallocene catalyst on comonomer incorporation, molecular weight of the copolymer and its distribution 6, 31, 42–44. Primary characteristics of the copolymer such as melting temperature and crystallinity are listed in Table 3 and 4.…”

Section: Resultsmentioning

confidence: 99%

“…During the isothermal crystallization steps, the separation of the crystalline material into groups of lamellae of different thickness depending on the amount and distribution of the α ‐olefin units in the macromolecular chain, takes place 44. Introduction of α ‐olefin in backbone of the polymer increases the heterogeneity of the polymer and decreases the lamellar thickness 45, 46.…”

Section: Resultsmentioning

confidence: 99%

Second international conference on accelerating biopharmaceutical development

Reichert¹,

Jacob

Amanullah³

2009

Biotechnology Progress

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The Second International Conference on Accelerating Biopharmaceutical Development was held in Coronado, California. The meeting was organized by the Society for Biological Engineering (SBE) and the American Institute of Chemical Engineers (AIChE); SBE is a technological community of the AIChE. Bob Adamson (Wyeth) and Chuck Goochee (Centocor) were co-chairs of the event, which had the theme "Delivering cost-effective, robust processes and methods quickly and efficiently." The first day focused on emerging disruptive technologies and cutting-edge analytical techniques. Day two featured presentations on accelerated cell culture process development, critical quality attributes, specifications and comparability, and high throughput protein formulation development. The final day was dedicated to discussion of technology options and new analysis methods provided by emerging disruptive technologies; functional interaction, integration and synergy in platform development; and rapid and economic purification process development.

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“…Nevertheless, some imperfection in the chain composition was apparent in case of copolymer obtained in run 15-the melting peak was somewhat irregular in its shape. It must be stressed that even metallocene catalysts which are considered single-site produce copolymers for which, after SSA fractionation, thermograms are obtained which contain several melting peaks [40]. To confirm those unexpected results, the SSA procedure was applied also for ethylene/1-decene copolymer with the highest comonomer content and produced by the vanadium catalyst (run 53, Table 2).…”

Section: Effect Of Comonomer Concentration and Catalyst Type On Hetermentioning

confidence: 94%

Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand

2013

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Ethylene/1-olefin copolymerization using vanadium and titanium complexes bearing tetradentate [O,N,N,O]-type ligand and EtAlCl 2 or MAO as a cocatalyst is carried out. In the presence of the vanadium complex activated with EtAlCl 2 is observed (a) negative ''comonomer effect'', (b) high comonomer incorporation and narrow chemical composition distribution (CCD), (c) unexpected copolymer microstructure, and (d) increased molecular weight of copolymers when compared with the homopolymer. In contrast, titanium catalyst gives copolymers with lower 1-olefin content and broad CCD. Supported complexes show higher activity, lower 1-olefins incorporation and give copolymers with ultra high molecular weights.

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Studies of structural composition distribution heterogeneity in ethylene/1-hexene copolymers using thermal fractionation technique (SSA)

Cited by 28 publications

References 22 publications

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Second international conference on accelerating biopharmaceutical development

Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand

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