Cross-slot extensional rheometry and the steady-state extensional response of long chain branched polymer melts

Auhl, Dietmar; Hoyle, David M.; Hassell, David; Lord, T. D.; Harlen, Oliver G.; Mackley, M. R.; McLeish, Tom

doi:10.1122/1.3589972

Cited by 28 publications

(22 citation statements)

References 64 publications

(3 reference statements)

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“…On the other hand, the filament stretching rheometer (FSR) is able to establish an effective steady state indicating that, for industrial melts like the socalled DOW 150 R sample, g þ E ðt; _ Þ undergoes an overshoot under kinematically steady flow [Rasmussen et al (2005); Hoyle et al (2013); Huang (2013)]. The observation of these overshoots is also supported by extensional viscosity measurements in a cross-slot flow [Hoyle (2011); Auhl et al (2011); Hoyle et al (2013)]. Nevertheless, some studies suggest that these overshoots are not a real material property but they emerge due to nonuniformities of the sample at high Hencky strains [Burghelea et al (2011)].…”

Section: Introductionmentioning

confidence: 82%

“…1). This is also the case at rates r4 and r5; nevertheless, for those rates, the cross-slot flow measurements [Hoyle (2011);Auhl et al (2011)] indicate that the steady state is even lower than the apparent steady state of the FSR data. At the highest rate, the maximum is slightly underestimated.…”

Section: Figmentioning

confidence: 93%

“…At this rate, a steady state is not achieved in the FSR. The minimal model overestimates by 20% the steady state measurement of the cross-slot experiment [Hoyle (2011);Auhl et al (2011)]. The model also provides a reasonable fit to the shear data.…”

Section: Figmentioning

confidence: 93%

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Modifying the pom-pom model for extensional viscosity overshoots

Hawke¹,

Huang²,

Hassager³

et al. 2015

Journal of Rheology

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We have developed a variant of the pom-pom model that qualitatively describes two surprising features recently observed in filament stretching rheometer experiments of uniaxial extensional flow of industrial branched polymer resins: (i) Overshoots of the transient stress during steady flow and (ii) strongly accelerated stress relaxation upon cessation of the flow beyond the overshoot. Within the context of our model, these overshoots originate from entanglement stripping (ES) during the processes of normal chain retraction and branch point withdrawal. We demonstrate that, for a single mode, the predictions of our overshoot model are qualitatively consistent with experimental data. To provide a quantitative fit, we represent an industrial melt by a superposition of several individual modes. We show that a minimal version of our model, in which ES due to normal chain retraction is omitted, can provide a reasonable, but not perfect, fit to the data. With regard the stress relaxation after (kinematically) steady flow, we demonstrate that the differential version of tube orientation dynamics in the original pom-pom model performs anomalously. We discuss the reasons for this and suggest a suitable alternative. V C 2015 The Society of Rheology.[http://dx

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Section: Introductionmentioning

confidence: 82%

Section: Figmentioning

confidence: 93%

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Modifying the pom-pom model for extensional viscosity overshoots

Hawke¹,

Huang²,

Hassager³

et al. 2015

Journal of Rheology

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“…rudy.valette@mines-paristech.fr tions were validated in strong and/or complex flows in many recent studies [7][8][9][10][11][12][13][14][15]. However, the data of Bach et al [16] have shown an unexpected elongational thinning behaviour in "strong" elongational flows (where the strain rate was larger than the inverse Rouse relaxation time).…”

Section: Introductionmentioning

confidence: 91%

Experimental validation of a tube based constitutive equation for linear polymer melts with inter-chain tube pressure effect

Valette

Boukellal

Durin

et al. 2013

Mechanics & Industry

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“…Consequently in this paper, we shall compare uniaxial and planar extensional data. Auhl et al (2011) used a closed cell stagnation point (SP) flow to measure the planar steady-state extensional response of various polyethylenes produced using flow induced birefringence (FIB) patterns. Much work has been done to investigate complex flow geometries [e.g., Boukellal et al (2011);Coventry and Mackley (2008); Crowley et al…”

Section: Introductionmentioning

confidence: 99%

Transient overshoot extensional rheology of long-chain branched polyethylenes: Experimental and numerical comparisons between filament stretching and cross-slot flow

Hoyle

Huang²,

Auhl

et al. 2013

Journal of Rheology

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. SynopsisThis work analyses the high-strain extensional behavior of long-chain branched polyethylenes, employing two novel extensional rheometer devices, the filament stretching rheometer and the crossslot extensional rheometer. The filament stretching rheometer uses an active feedback loop to control the imposed strain rate on a filament, allowing Hencky strains of around 7 to be reached. The cross-slot extensional rheometer uses optical birefringence patterns to determine the steady-state extensional viscosity from planar stagnation point flow. The two methods probe different strain-rate regimes and in this paper we demonstrate the agreement when the operating regimes overlap and explore the steadystate extensional viscosity in the full strain-rate regime that these two complimentary techniques offer. For long-chain branched materials, the cross-slot birefringence images show a double cusp pattern around the outflow centre line (named W-cusps). Using constitutive modeling of the observed transient overshoot in extension seen in the filament stretching rheometer and using finite element simulations we show that the overshoot explains the W-cusps seen in the cross-slot extensional rheometer, further confirming the agreement between the two experimental techniques. V C 2013 The Society of Rheology.[http://dx

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Cross-slot extensional rheometry and the steady-state extensional response of long chain branched polymer melts

Cited by 28 publications

References 64 publications

Modifying the pom-pom model for extensional viscosity overshoots

Modifying the pom-pom model for extensional viscosity overshoots

Experimental validation of a tube based constitutive equation for linear polymer melts with inter-chain tube pressure effect

Transient overshoot extensional rheology of long-chain branched polyethylenes: Experimental and numerical comparisons between filament stretching and cross-slot flow

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