The effect of heterogeneity on the flow behavior on high density polyethylene

Shida, Mitsuzo; Cancio, L. V.

doi:10.1002/app.1970.070141211

Cited by 7 publications

(1 citation statement)

References 18 publications

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“…In extrusion blending, the maximum volume fraction of the UHMWPE is usually limited due to the extremely high melt viscosity of UHMWPE . Moreover, the homogeneity of the extrusion blends is usually rather poor due to the large viscosity differences between, for instance, high‐density polyethylene (HDPE; Mw < 200 kg mol −1 ) and UHMWPE (Mw > 1000 kg mol −1 ) …”

Section: Introductionmentioning

confidence: 99%

Rheological properties of bimodal polyethylenes produced with silica nanoparticle supported catalysts

Líu

Troisi

Goossens

et al. 2019

J of Applied Polymer Sci

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The rheological properties of bimodal ultra-high-molecular-weight polyethylenes (UHMWPEs) are investigated with an emphasis on the influence of the catalyst support. Bimodal UHMWPEs were produced in a single reactor with double support (DS) and single support (SS) catalyst systems. Dynamic measurements showed that the SS samples have a higher storage modulus at low frequencies than the DS samples with the same weight average molecular weight. After extrusion, the storage modulus of the bimodal DS samples increased to an identical value. The results indicate that the SS sample has a higher homogeneity than the DS sample. The steady-shear viscosities were measured to determine zero shear viscosities (η 0 ) of the bimodal samples. The results show that the SS samples follow the relation η 0 = KM w α with α = 3.19. However, the DS samples exhibit a substantial deviation from this relation especially in the intermediate M w range around 1000 kg mol −1 . The reason for the deviation is attributed to the heterogeneity in DS samples. The results demonstrate that the DS systems do not produce bimodal PEs with an intimate degree of mixing of short and long polymer chains even if silica nanoparticles are used as the support.In the case of a heterogeneous catalyst, the polymer chains grow on the catalyst particles and form polymer particles after polymerization. 23 In the case of SS system, the catalysts are located on the same particle surface and thus the low-molecular-weight Additional Supporting Information may be found in the online version of this article.

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Section: Introductionmentioning

confidence: 99%

Rheological properties of bimodal polyethylenes produced with silica nanoparticle supported catalysts

Líu

Troisi

Goossens

et al. 2019

J of Applied Polymer Sci

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Correlation of low density polyethylene rheological measurements, with optical and processing properties

Shida¹,

Cancio²

1977

Polymer Engineering & Sci

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The processing properties of' low density polyethylene melts, such as drawdown and neck-in, and the final product properties, such as film haze and gloss, have been successfully correlated with rheological functions and the level of longchain branching. The rheological functions employed are the entrance pressure drop AP,, and the swell ratio So, determined at a specified shear stress using an orifice with a length/ diameter (LID) ratio of zero. The calculation of shear stress requires additional measurements using a die with a finite LID e.g. 20. The rheological functions AP,, and S,, are governed by the level of high molecular weight species and/or the level of long-chain branching(LCB). If determined at a constant shear stress, in order to eliminate the effect of viscosity, they are a relative measure of elasticity. Higher AP, and S,, indicate a higher level of LCB and correlate with poorer optical properties and drawdown in films.

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Viscosity–molecular weight–temperature–shear rate relationships of polymer melts: A literature review

Kumar

1980

J. Polym. Sci. Macromol. Rev.

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The effect of heterogeneity on the flow behavior on high density polyethylene

Cited by 7 publications

References 18 publications

Rheological properties of bimodal polyethylenes produced with silica nanoparticle supported catalysts

Rheological properties of bimodal polyethylenes produced with silica nanoparticle supported catalysts

Correlation of low density polyethylene rheological measurements, with optical and processing properties

Viscosity–molecular weight–temperature–shear rate relationships of polymer melts: A literature review

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