Crystaf: Crystallization analysis fractionation. A new approach to the composition analysis of semicrystalline polymers

Monrabal, Benjamín

doi:10.1002/masy.19961100107

Cited by 85 publications

(50 citation statements)

References 4 publications

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“…1,2,11 It has been shown that CRYSTAF and TREF results are similar. However, one of the advantages of CRYSTAF is that the analysis time is much shorter than the one required by TREF.…”

Section: Crystallization Analysis Fractionation-crystafsupporting

confidence: 51%

Polyolefin analysis by single-step crystallization fractionation

Britto

Soares

Penlidis

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…1,2,11 It has been shown that CRYSTAF and TREF results are similar. However, one of the advantages of CRYSTAF is that the analysis time is much shorter than the one required by TREF.…”

Section: Crystallization Analysis Fractionation-crystafsupporting

confidence: 51%

Polyolefin analysis by single-step crystallization fractionation

Britto

Soares

Penlidis

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…By monitoring the polymer solution concentration during crystallization, the cumulative and differential SCBD can be obtained without the need to physically separate the fractions. CRYSTAF produces similar results to TREF but in a shorter time and with a simplified apparatus [7][8][9] . Much effort has been focused on the relationship between the structure of active sites and microstructure of polymer chains because of the very broad range of product applications [10][11][12] .…”

Section: Introductionsupporting

confidence: 75%

“…Copolymer microstructure was analyzed by 13 C NMR according to the method reported by Randall 14) . CRYSTAF measurements were carried out as described in the literature 8) .…”

Section: Polymerization and Characterizationmentioning

confidence: 99%

“…The most common technique for this purpose has been temperature rising elution fractionation (TREF), which was first described by Desreux and Spiegels in 1950 5) , and further established by Wild et al 6) with the development of analytical TREF, which is now a common technique in the polyolefins industry. On the other hand, a new technique to analyze the SCBD of ethylene copolymers has been recently introduced 7,8) . This technique, crystallization analysis fractionation (CRYSTAF), is based on a stepwise precipitation approach similar to TREF.…”

Section: Introductionmentioning

confidence: 99%

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The influence of the Ti3+ species on the microstructure of ethylene/1-hexene copolymers

Chu

Soares²,

Penlidis

et al. 1999

Macromol. Chem. Phys.

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SUMMARY: Copolymerization of ethylene and 1-hexene was carried out with catalysts having isolated Ti 3+ and multinuclear Ti 3+ species. Carbon-13 nuclear magnetic resonance spectroscopy ( 13 C NMR), crystallization analysis fractionation (CRYSTAF), and gel permeation chromatography (GPC) studies showed that the microstructure of ethylene and 1-hexene copolymers strongly depends upon the structure of the Ti 3+ species. Isolated Ti 3+ species increase the relative reactivity of ethylene in copolymerizations and produce copolymers with high molecular weight and broad short chain branching distribution (SCBD), with a large ethylene-rich fraction. Multinuclear Ti 3+ species increase the relative reactivity of 1-hexene and produce copolymers with low molecular weight and broad SCBD, with a large rubbery ethylene/1-hexene fraction. Comparative studies of the copolymer microstructure from isolated Ti 3+ and multinuclear Ti 3+ in combination with different cocatalysts, Al(CH 3 ) 3 , Al(C 2 H 5 ) 3 , and methylaluminoxane (MAO) were also carried out. Isolated Ti 3+ species in combination with MAO cause remarkable changes in the 1-hexene incorporation rate and SCBD in comparison with Al(CH 3 ) 3 and Al(C 2 H 5 ) 3 , while multinuclear Ti 3+ species in combination with MAO do not affect as much the 1-hexene incorporation rate. This difference may be related to the mechanism of active site formation between the different Ti 3+ structures and MAO.

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“…The fractionation principle of this technique is already published in the literature [33][34][35]. The sample solution of concentration 0.1% (w/w) was prepared in 1, 2, 4 trichlorobenzene (TCB) at 160°C under stirring for 60 min.…”

Section: Copolymer Composition Distributionmentioning

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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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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Crystaf: Crystallization analysis fractionation. A new approach to the composition analysis of semicrystalline polymers

Cited by 85 publications

References 4 publications

Polyolefin analysis by single-step crystallization fractionation

Polyolefin analysis by single-step crystallization fractionation

The influence of the Ti3+ species on the microstructure of ethylene/1-hexene copolymers

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

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