Rheological properties of short fiber filled polypropylene in transient shear flow

Sepehr, Maryam; Ausias, Gilles; Carreau, Pierre J.

doi:10.1016/j.jnnfm.2004.06.005

Cited by 113 publications

(114 citation statements)

References 33 publications

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“…The gap between the stationary and moving plate of the SPR was kept at 1.50 mm and yields a gap to fiber diameter ratio of approximately 100 for all glass systems analyzed. This ratio is above the ratio used for short glass fiber samples, as proposed in the work of Sepehr et al (2004) and Eberle et al (2010). The effect of gap on LGF samples, however, has not yet been determined.…”

Section: Sliding Plate Rheometermentioning

confidence: 74%

Using startup of steady shear flow in a sliding plate rheometer to determine material parameters for the purpose of predicting long fiber orientation

Ortman¹,

Baird²,

Wapperom³

et al. 2012

Journal of Rheology

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SynopsisThe properties of long glass fiber reinforced parts, such as those manufactured by means of injection molding and compression molding, are highly dependent on the fiber orientation generated during processing. A sliding plate rheometer was used to understand the transient stress and orientation development of concentrated long glass fibers during the startup of steady shear flow. An orientation model and stress tensor combination, based on semiflexible fibers, was assessed in its ability to predict fiber orientation when using model parameters obtained from the fits of the stress responses. Specifically, samples of different initial fiber orientations was subjected to the startup of steady shear flow, and an orientation model based on bead and rod theory was coupled with a derived stress tensor that accounts for the semiflexibility of the fibers to obtain the corresponding model parameters. The results showed the semiflexible orientation model and stress tensor combination, overall, provided improved rheological results as compared to the Folgar-Tucker model when coupled with the stress tensor of Lipscomb et al. [J. Non-Newtonian Fluid Mech. 26, 297-325 (1988)]. Furthermore, it was found that both stress tensors required empirical modification to accurately fit the measured data. Finally, orientation models provided encouraging results when predicting the transient fiber orientation for all initial fiber orientations explored. V C 2012 The Society of Rheology. [http://dx

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Section: Sliding Plate Rheometermentioning

confidence: 74%

Using startup of steady shear flow in a sliding plate rheometer to determine material parameters for the purpose of predicting long fiber orientation

Ortman¹,

Baird²,

Wapperom³

et al. 2012

Journal of Rheology

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show abstract

“…Typically a closure approximation is used in the fiber orientation or stress equations as a computationally efficient way of representing a higher order tensor as a function of lower order tensors. However, the use of a closure approximation induces error that can significantly impact the stress predictions [45]. As a result, the evaluation of the stress equation becomes dependent on the closure approximation.…”

Section: Stress Predictionmentioning

confidence: 99%

Influence of fiber concentration on the startup of shear flow behavior of long fiber suspensions

Cieslinski

Wapperom

Baird

2015

Journal of Non-Newtonian Fluid Mechanics

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a b s t r a c tIn order to use rheological measurements as a tool to investigate fiber orientation in simple flows, the relationship between stress and fiber orientation must be understood. In this work, a sliding plate rheometer was used to measure the shear stress growth during the startup of simple shear flow of a polymer melt containing long glass fibers. The concentrations of the suspensions were varied from 10 to 40 wt% and tested over three shear rates spanning an order of magnitude. Significant shear thinning was observed in the suspension as concentration increased. Additionally, the magnitude of stress and breadth of the stress growth overshoot increased with concentration. A larger distinction between the different concentrations is observed in the shear stress growth than the measured evolution of fiber orientation. Measured values of fiber orientation were used with a semi-dilute stress equation to show that the fiber motion in these experiments was not responsible for the stress overshoot and that additional stress contributions must be considered.

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“…This value corresponds to the average value of those used in the literature for fibre suspensions displaying similar fibre content and aspect ratio [8,43,46]. -From the plane strain compression experiments, H can be directly deduced from the stress ratio σ 33 /σ 22 since…”

Section: Identification Of Constitutive Parametersmentioning

confidence: 96%

Towards the simulation of mould filling with polymer composites reinforced with mineral fillers and short fibres

et al. 2009

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Bulk Moulding Compounds (BMC's) are short fibre reinforced polymer composites that behave, during their forming, as concentrated fibre suspensions. Their suspending fluid is also a concentrated granular suspension made up of the polymer filled with mineral fillers. In this work, a method is proposed to model their flow. Firstly, the rheology of an industrial BMC was analysed by performing two types of mechanical tests, i.e. lubricated simple and plane strain compression experiments. Experimental results underline the roles of the current strain, the strain rate as well as the mechanical loading on the rheology of the BMC. Secondly, a 3D tensorial rheological model is proposed to reproduce the simple and plane strain compression experiments. Then this model is implemented into a Finite Element code dedicated to the simulation of The 'Pôle de Compétitivité Plastipolis' (Région Rhône-Alpes -France) supports this research. compression moulding. Simulation results are finally compared with experiments achieved with rather complex flow situations.

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Rheological properties of short fiber filled polypropylene in transient shear flow

Cited by 113 publications

References 33 publications

Using startup of steady shear flow in a sliding plate rheometer to determine material parameters for the purpose of predicting long fiber orientation

Using startup of steady shear flow in a sliding plate rheometer to determine material parameters for the purpose of predicting long fiber orientation

Influence of fiber concentration on the startup of shear flow behavior of long fiber suspensions

Towards the simulation of mould filling with polymer composites reinforced with mineral fillers and short fibres

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