HDPE/LLDPE reactor blends with bimodal microstructures—Part II: rheological properties

Shan, Colin Li Pi; Soares, João B. P.; Penlidis, Alexander

doi:10.1016/s0032-3861(02)00721-8

Cited by 53 publications

(48 citation statements)

References 13 publications

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“…4,5,[11][12][13][14][15][16][17][18] Several studies have shown that ethylene polymerizations with combinations of different catalysts and variations of the polymerization processes can produce reactor blends with improved physical and/or chemical properties. 1,4,5,[11][12][13][19][20][21][22] In most of the early reports, metallocene catalysts such as titanium, zirconium, and hafnium compounds were the main choices for catalyst combinations. 11,23,24 Some catalysts combined in a polymerization reactor have been successful in producing ethylene homopolymer independently, 5,[15][16][17] and this suggests that the active sites are not affected by interactions between the different site types present in the polymerization mixtures.…”

Section: -10mentioning

confidence: 99%

“…That team also investigated the relationship between the composition of resins and their physical properties. 4,13 Wu et al 27 studied the crystalline structure and phase structure of metallocene linear low-density PE and low-density PE blends, and they found that both a cocrystallization phenomenon and phase separation existed. In addition, Mandelkern et al 28 reported that the extent of cocrystallization of blends with different types of PE was governed by the closeness of the crystallization rates of each component.…”

Section: -10mentioning

confidence: 99%

“…The MW and MWD values were obtained with a polystyrene standard for these PE blends with different degrees of branching. The degree of branching of the branched PE obtained from the pure nickel complex was determined by quantitative 13 C-NMR spectroscopy. The measurement was performed at 120 C on a Varian Unity 400 (Bruker, Switzerland) with o-dichlorobenzene as the solvent.…”

Section: Polymer Characterizationmentioning

confidence: 99%

“…Figure 2 shows quantitative 13 C-NMR spectra of A1, A10, and B8. The branching degree of PE was calculated according to the rules of Galland and Qiujada.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

See 3 more Smart Citations

Influence of branching on the thermal and crystallization behavior of bimodal polyethylenes synthesized with binary late‐transition‐metal catalyst combinations

Long

Liu

Cui

et al. 2009

J of Applied Polymer Sci

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Two reactor blends of linear and branched polyethylene resins with bimodal molecular weight distributions were synthesized in a one-reactor polymerization process through the combination of 2,6-bis[1-(2,6-dimethyphenylimino)pyridyl]cobalt dichloride (1) and 2,3-bis(2,6-diisopropylphenyl)butanediimine nickel dibromide (2) or 1,2-bis(2,6-diisopropylphenyl)cyclohexene diimine nickel dibromide (3) in the presence of modified methylaluminoxane. The linear correlation between the catalyst activity and concentration of the nickel compounds suggested that the catalysts performed independently of one another. The molecular weights, molecular weight distributions, and crystalline and phase structures of the blends were investigated with a combination of high-temperature gel permeation chromatography, differential scanning calorimetry, wideangle X-ray diffraction, and small-angle X-ray scattering techniques. The branching degree of the polyethylene produced with 3 was much higher than the branching degree of the sample produced with 2, although their molecular weights were relatively close. In addition, the crystallization rate, melting temperature, degree of crystallinity, and crystallization temperature of more highly branched blends produced with 1/3 were lower. The long periods and thickness of the crystalline region were greatly influenced by the addition of highly branched polyethylene.

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Section: -10mentioning

confidence: 99%

Section: -10mentioning

confidence: 99%

Section: Polymer Characterizationmentioning

confidence: 99%

“…Figure 2 shows quantitative 13 C-NMR spectra of A1, A10, and B8. The branching degree of PE was calculated according to the rules of Galland and Qiujada.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

See 2 more Smart Citations

Influence of branching on the thermal and crystallization behavior of bimodal polyethylenes synthesized with binary late‐transition‐metal catalyst combinations

Long

Liu

Cui

et al. 2009

J of Applied Polymer Sci

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“…• improving the mechanical properties [94] • increasing the yield of the catalyst [30,95,96] • improving the morphology of the polymer [29,95,97,98] • improving the rheological behaviour of the polymer [99] • removing of sintering, agglomeration and fines generation [47].…”

Section: Introductionmentioning

confidence: 99%

Comparison of catalytic ethylene polymerization in slurry and gas phase

Daftari‐Besheli¹

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Thermal and crystallization behaviors of polyethylene blends synthesized by binary late transition metal catalysts combinations

Pan

Zhang

et al. 2007

J of Applied Polymer Sci

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A series of reactor blends of linear and branched polyethylenes have been prepared, in the presence of modified methylaluminoxane, using a combination of 2,6-bis[1-(2,6-dimethyphenylimino) pyridyl]-cobalt(II) dichloride (1), known as an active catalyst for producing linear polyethylene, and [1,4-bis(2,6-diidopropylphenyl)] acenaphthene diimine nickel(II) dibromide (2), which is active for the production of branched polyethylene. The polymerizations were performed at various levels of catalyst feed ratio at 10 bar. The linear correlation between catalyst activity and concentration of catalyst 2 suggested that the catalysts performed independently from each other. The weight-average molecular weights ðM w Þ, crystalline structures, and phase structures of the blends were investigated, using a combination of gel permeation chromatography, differential scanning calorimetry, wide-angle X-ray diffraction, and small angle X-ray scattering techniques. It was found that the polymerization activities and MWs and crystallization rate of the polymers took decreasing tendency with the increase of the catalyst 2 ratios, while melting temperatures (T m ), crystalline temperatures (T c ), and crystalline degrees took decreasing tendency. Long period was distinctly influenced by the amorphous component concentration.

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HDPE/LLDPE reactor blends with bimodal microstructures—Part II: rheological properties

Cited by 53 publications

References 13 publications

Influence of branching on the thermal and crystallization behavior of bimodal polyethylenes synthesized with binary late‐transition‐metal catalyst combinations

Influence of branching on the thermal and crystallization behavior of bimodal polyethylenes synthesized with binary late‐transition‐metal catalyst combinations

Comparison of catalytic ethylene polymerization in slurry and gas phase

Thermal and crystallization behaviors of polyethylene blends synthesized by binary late transition metal catalysts combinations

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