NMR study of microstructure of ultra high‐molecular weight polytheylene

Kaji, Atsushi; Akitomo, Yoshiko; Murano, Masao

doi:10.1002/pola.1991.080291320

Cited by 16 publications

(9 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The differential scanning calorimetry (DSC) studies determine that the melting temperatures (Tm) values of polyethylene produced by Fe complex is in the range of 132–134 °C [Figure S9], which is in line with previously reported Tm for commercial polyethylene samples . The 13 C NMR measurements of representative polyethylene sample shows no signals for branches thus confirming their high linearity, which agreed with previous reports [Figure S9] …”

Section: Methodssupporting

confidence: 90%

“…The differential scanning calorimetry (DSC) studies determine that the melting temperatures (Tm) values of polyethylene produced by Fe complex is in the range of 132-134°C [ Figure S9], which is in line with previously reported Tm for commercial polyethylene samples. [51] The 13 C NMR measurements of representative polyethylene sample shows no signals for branches thus confirming their high linearity, which agreed with previous reports [ Figure S9]. [52] Gel permeation chromatography (GPC) analysis demonstrates that the polyethylenes produced by the Fe complex 3 possess unimodal molecular weight distribution with the moderate molecular weight values (Mw) in the range of 556000-871000 g/ mole (Table 1, Figure 4).…”

Section: Ethylene Polymerization Using Site-selective Pyridine-amide supporting

confidence: 88%

See 1 more Smart Citation

Ethylene Polymerization Using Site‐Selective Pyridine‐Amide Based Iron Complexes

et al. 2019

View full text Add to dashboard Cite

The ligand N’,N’‐bis(6‐chloropyridin‐3‐yl)pyridine‐2,6‐dicarboxamide (1) in their di‐deprotonated forms have been used to synthesize two new iron (III) 2 and 3 metal complexes. The iron(III) is surrounded by two tridentate ligands for complex 2, and one tridentate ligand for complex 3. Both complexes have been characterized by NMR, UV‐Visible, IR spectroscopy and elemental analysis. The solid‐state structure of 2 was determined by X‐ray diffraction analysis. Both iron complexes were further studied for ethylene polymerization in the presence of co‐catalyst methylaluminoxane (MAO) under various reaction conditions. It was found that the pincer containing complex 3 exhibited good activities for ethylene polymerization at 80 °C, while the bis‐ligated iron complex 2 did not show activity for ethylene polymerization.

show abstract

Section: Methodssupporting

confidence: 90%

Section: Ethylene Polymerization Using Site-selective Pyridine-amide supporting

confidence: 88%

Ethylene Polymerization Using Site‐Selective Pyridine‐Amide Based Iron Complexes

et al. 2019

View full text Add to dashboard Cite

show abstract

“…They were taken from the work of Hansen et al 1 and Kaji et al 2 We chose to use the numbering system of Hansen et al, in which the branch itself is numbered, starting from the methyl group and counting back to the main chain, and includes the length of the branch; the branch methine carbon is numbered for the length of the branch; and the main chain is lettered relative to the distance from the branch. An example is shown next for a four-carbon branch:…”

Section: Methodsmentioning

confidence: 99%

Complementarity of universal calibration SEC and 13C NMR in determining the branching state of polyethylene

Striegel¹,

Krejsa²

2000

J. Polym. Sci. B Polym. Phys.

View full text Add to dashboard Cite

“…Based on 13 C NMR measurements, short branches, mainly n-butyl and some ethyl branches, were observed. 24 Upon increasing the silica calcination temperature, n-butyl branches per 1000 C significantly increased versus ethyl branches. Ethyl branches gradually increased with silica calcination temperature.…”

Section: Effects Of Silica Calcination Temperaturementioning

confidence: 96%

Ethylene Polymerization with Silica-Supported Cr[N(SiMe3)2]3/Alumoxane Catalyst

Monoi¹,

Ikeda²,

Ohira³

et al. 2002

Polym J

View full text Add to dashboard Cite

ABSTRACT:A new silica-supported non-cyclopentadienyl chromium catalyst having high activity for ethylene polymerization is presented. The catalyst was prepared by supporting tris[bis(trimethylsilyl)amido]chromium(III) Cr[N(SiMe 3 ) 2 ] 3 and alumoxane on silica. The best activity was attained by supporting Cr[N(SiMe 3 ) 2 ] 3 (0.2 wt%-Cr for silica) on silica calcined at 350• C and next supporting a modified-methylalumoxane (Al/Cr molar ratio = 20). Activity during the slurry-phase polymerization was 75100 g-PE/mmol-Cr·hr at 103• C and 1.4 MPa ethylene partial pressure in isobutane. The obtained polyethylene had a relatively high molecular weight and broad molecular weight distribution (HLMFR = 15.6 g/10 min, M w = 330000, M w /M n = 33.0). The calcination temperature of silica had significant influence on the catalyst performance. As calcination temperature increased, short branches, mainly n-butyl and some ethyl branches, were introduced into the resulting polyethylene. There has been increasing interest in the discovery and development of non-cyclopentadienyl transition metal catalysts using titanium, zirconium, iron, nickel, and palladium for ethylene polymerization. [1][2][3][4] As for chromium as a transition metal, cyclopentadienyl complexes are well known for ethylene polymerization. [5][6][7][8][9][10][11][12] Recently, non-cyclopentadienyl chromium catalysts have been reported. [13][14][15][16][17][18][19][20][21][22] These homogeneous catalysts have moderate to high activity depending on the ligand structures. We have been exploring noncyclopentadienyl chromium catalysts because different characteristics could be expected for chromium as a group 6 element from the group 4 elements like titanium and zirconium, the group 8 element like iron and group 10 elements like nickel and palladium. We present a new heterogeneous non-cyclopentadienyl chromium catalyst having high activity for ethylene polymerization with unique features by supporting the tris[bis(trimethylsilyl)amido]chromium(III) complex Cr[N(SiMe 3 ) 2 ] 3 as a transition metal component and alumoxane as an organometallic component on silica. The characteristics of this catalyst influence polymerization activity and polymer structure (molecular weight, molecular weight distribution, and chain branching). The polymerization mechanism is discussed.

show abstract

NMR study of microstructure of ultra high‐molecular weight polytheylene

Cited by 16 publications

References 20 publications

Ethylene Polymerization Using Site‐Selective Pyridine‐Amide Based Iron Complexes

Ethylene Polymerization Using Site‐Selective Pyridine‐Amide Based Iron Complexes

Complementarity of universal calibration SEC and 13C NMR in determining the branching state of polyethylene

Ethylene Polymerization with Silica-Supported Cr[N(SiMe3)2]3/Alumoxane Catalyst

Contact Info

Product

Resources

About