The damping function in rheology

Rolón-Garrido, Víctor H.; Wagner, Manfred H.

doi:10.1007/s00397-008-0308-x

Cited by 99 publications

(86 citation statements)

References 238 publications

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“…a). The corresponding maximum endurable stress of 10 MPa was reported earlier for partially crosslinked LDPE . Consequently a physical separation of the polymer structure or even scission of primary bonds can be expected.…”

Section: Resultssupporting

confidence: 69%

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Kruse

Wang

Shah

et al. 2018

Polymer Engineering & Sci

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Three grades of poly(ethylene terephthalate) (PET) produced by different synthesis routes and with different molar masses were reactively extruded with two tetra‐functional chain extenders, i.e., pyromellitic dianhydride (PMDA) and tetraglycidyl diamino diphenyl methane (TGDDM). The preferred reactivity of the coupling agents led to different long‐chain branched (LCB) structures, which can be related to different hydroxyl and carboxyl end group concentrations of the PET grades investigated. The complex viscosity and the transient elongational viscosity increased by up to two decades. Both the activation energy of flow and the loss angle indicate long‐chain branching. A more quantitative assessment of the extent of strain hardening was achieved by application of the molecular stress function (MSF) model. The two material parameters of the model revealed different behaviors depending on the chain extender used. The initial molar mass of PET and the concentration of end groups, i.e., hydroxyl and carboxyl, determine the structure of the polymer molecules. PMDA proved to be an excellent coupling agent for industrial processing which induces reproducibly either a star‐like, comb‐like, or randomly branched structure depending on the concentration of coupling agent added and the hydroxyl concentration of the PET employed. TGDDM led to a hyperbranched structure. POLYM. ENG. SCI., 59:396–410, 2019. © 2018 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 69%

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Kruse

Wang

Shah

et al. 2018

Polymer Engineering & Sci

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“…This failure of Larson model at high shear rates could be attributed to the probability that the polymer strands could not contact to the extent, equivalent to what is described by the single strain‐softening parameter(

ξ^{'}

) in the Larson model, because the shear rates are too fast. It is like the situation that the damping function predicted by the Doi–Edwards theory are stronger than the experimental data, because the retraction of the polymer strands is complete inside the virtual tube proposed by Doi and Edwards . The experimental and the predicted η E data are illustrated in Figs.…”

Section: Resultsmentioning

confidence: 82%

“…The damping function, h ( γ ), has been a concept introduced in rheology since more than 30 years ago, and its implementation in the modeling of polymer melts was an essential step forward in the classification and understanding of nonlinear viscoelasticity . Most of nonlinear viscoelastic behaviors can be described by utilizing h ( γ ) determined from stress relaxation measurements .…”

Section: Introductionmentioning

confidence: 99%

Evaluate the nonlinear viscoelasticity of polyolefin melts using the Larson model

Lin

Song

Shiu³

et al. 2013

Polymer Engineering & Sci

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Nonlinear rheological properties of polyolefins have long been studied and predicted by using the Larson model with the damping function generally obtained from the stress relaxation measurements. In this study, we investigate the nonlinear rheological properties of high density polyethylene (HDPE) and polypropylene (PP) using the Larson model with damping functions obtained from either the dynamic frequency sweep or the stress relaxation test. Experimental measurements and their corresponding model predictions for the rheological parameters were then compared to evaluate the applicability of the Larson model to the nonlinear rheology, and the following conclusions could be achieved. The steady shear viscosity could be satisfactorily described by the Larson model with the damping functions obtained from the two different methods, except at shear rates higher than 103 s−1. The predicted first normal stresses also account for the measured data, except for those using the stress relaxation data showing a little deviation for the PP sample. In addition, the predictions for elongation viscosity are also in good agreement with the experimental results within the short range of elongation rate achieved in this work. POLYM. ENG. SCI., 54:2354–2361, 2014. © 2013 Society of Plastics Engineers

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“…This function depends on the two Invariants and of the Finger strain tensor as well as the two damping parameters and . [4] (4)…”

Section: Materials Modellingmentioning

confidence: 99%

Material characterization for thermoforming-simulation

Landsecker¹,

Bonten²

2016

AIP Conference Proceedings

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Abstract. In order to obtain high prediction accuracy in thermoforming-simulation a material-testing-method close to the actual thermoforming process is needed. Therefore scientists at the IKT developed a specific test for thermoforming material characterization (TMC-test). Besides the general description of a material's thermoforming characteristics, the TMC-test provides material data for thermoforming-simulation. First of all, the IKT's procedure for thermoforming-simulation is described. The setup of the IKT's TMC-apparatus is explained and it is examined how material parameters can be extracted from the TMC-test by reverse-engineering. Finally, the IKT's method for thermoforming-simulation is validated by an exemplary thermoforming-simulation. The prediction accuracy of the new procedure is being quantified by the relation of processed and simulated sheet-thicknessdistribution.

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The damping function in rheology

Cited by 99 publications

References 238 publications

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Evaluate the nonlinear viscoelasticity of polyolefin melts using the Larson model

Material characterization for thermoforming-simulation

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