Stress and recovery maxima in LDPE melt elongation

Raible, T.; Demarmels, A.; Meißner, J.

doi:10.1007/bf00284409

Cited by 61 publications

(10 citation statements)

References 9 publications

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“…A maximum in the transient extensional stress of LDPE was observed by several groups [8,9,10]. Steady stress following the stress overshoot was reported firstly by Rasmussen et al [11] and has been experimentally confirmed by comparing the measurements from the filament stretching rheometer and the cross-slot extensional rheometer [12], as well as by comparing the constant stretch rate and constant stress (creep) experiments [13].…”

Section: Introductionmentioning

confidence: 75%

A new look at extensional rheology of low-density polyethylene

et al. 2016

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The nonlinear rheology of three selected commercial low-density polyethylenes (LDPE) is measured in uniaxial extensional flow. The measurements are performed using three different devices including an extensional viscosity fixture (EVF), a home made filament stretching rheometer (DTU-FSR) and a commercial filament stretching rheometer (VADER-1000). We show that the measurements from the EVF are limited by a maximum Hencky strain of 4, while the two filament stretching rheometers are able to probe the nonlinear behavior at larger Hencky strain values where the steady state is reached. With the capability of the filament stretching rheometers, we show that LDPEs with quite different linear viscoelastic properties can have very similar steady extensional viscosity. This points to the potential for independently controlling shear and extensional rheology in certain rate ranges.

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Section: Introductionmentioning

confidence: 75%

A new look at extensional rheology of low-density polyethylene

et al. 2016

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“…However, many commercially available polymers, such as LDPE, are branched and highly polydisperse. A maximum in the transient elongational stress coefficient of LDPE was observed by Raible et al (1979) and modeled by for the first time. Recently, Read et al (2011) proposed a predictive scheme of the linear and nonlinear response for industrial polymers.…”

Section: Introductionmentioning

confidence: 86%

Stress relaxation and reversed flow of low-density polyethylene melts following uniaxial extension

Huang¹,

Rasmussen²,

Skov³

et al. 2012

Journal of Rheology

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SynopsisThe extensional dynamics of two low-density polyethylene melts Lupolen 3020D and Lupolen 1840D, both showing a stress overshoot in start-up of uniaxial extension [Rasmussen, H. K., J. K. Nielsen, A. Bach, and O. Hassager, "Viscosity overshoot in the start-up of uniaxial elongation of low density polyethylene melts," J. Rheol. 49(2), 369-381 (2005)], have been further investigated in stress relaxation and reversed flow. After the overshoot, the stress relaxation has a remarkably faster decrease of the transient stress than when the relaxation is initiated before the overshoot. The measurements from the reversed flow also show that the melts appear less elastic after the overshoot. Multi mode versions of the pom-pom and interchain pressure model fit the data quantitatively up to the stress maximum, but neither model captures the qualitative behavior after the maximum. V C 2012 The Society of Rheology. [http://dx

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“…With an improved version of the rheometer used for the measurements presented in the Figures 1 and 2, elongations up to İ H = 7 could be reached for samples of a LDPE very similar to IUPAC A. Flat maxima of the tensile stress and the recoverable strain are reported [21] which occur at Hencky strains between 5 and 6, i.e. just close to the highest extensions of the experiments in the two figures above for the same elongational rates of e 0 = 0.1 s -1 and e 0 = 0.03 s -1 .…”

Section: Stressing Experimentsmentioning

confidence: 92%

Elongational experiments on polymer melts and their assessment

Münstedt¹

2013

AIP Conference Proceedings

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Abstract. Regarding the literature, steady-state values of the elongational viscosity are not widely documented and it is still an open question, whether the time-dependent elongational viscosity of strain-hardening polymeric materials runs through a maximum as a function of time before it reaches its steady state. For the assessment of molecular theories reliable experimental data are essential, however. From a survey of extensional experiments at constant elongational rates it becomes very probable that an extended stationary state of elongational exists and that maxima of the tensile stresses or even overshoot phenomena are due to non-uniform deformations of the samples. This conclusion is supported by creep experiments for which a steady state is reached at comparatively smaller total elongations corresponding to a better uniformity.

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Stress and recovery maxima in LDPE melt elongation

Cited by 61 publications

References 9 publications

A new look at extensional rheology of low-density polyethylene

A new look at extensional rheology of low-density polyethylene

Stress relaxation and reversed flow of low-density polyethylene melts following uniaxial extension

Elongational experiments on polymer melts and their assessment

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