Towards the Development of a Strategy to Characterize and Model the Rheological Behavior of Filled, Uncured Rubber Compounds

Spanjaards, Michelle M. A.; Peters, Gwm Gerrit; Hulsen, Martien A.; Anderson, Patrick Patrick

doi:10.3390/polym13234068

Cited by 4 publications

(2 citation statements)

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“…When the material is deformed, these bonds can break, but after flow cessation, these bonds can reform again. To model this thixotropic behavior, a structure parameter ξ is defined which indicates the degree of structure in the material, as discussed in Spanjaards et al [23]. If ξ = 1, the material is undamaged and the filler-filler/polymer-filler networks are intact.…”

Section: Thixotropy Modelmentioning

confidence: 99%

Numerical Study of the Effect of Thixotropy on Extrudate Swell

et al. 2021

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The extrusion of highly filled elastomers is widely used in the automotive industry. In this paper, we numerically study the effect of thixotropy on 2D planar extrudate swell for constant and fluctuating flow rates, as well as the effect of thixotropy on the swell behavior of a 3D rectangular extrudate for a constant flowrate. To this end, we used the Finite Element Method. The state of the network structure in the material is described using a kinetic equation for a structure parameter. Rate and stress-controlled models for this kinetic equation are compared. The effect of thixotropy on extrudate swell is studied by varying the damage and recovery parameters in these models. It was found that thixotropy in general decreases extrudate swell. The stress-controlled approach always predicts a larger swell ratio compared to the rate-controlled approach for the Weissenberg numbers studied in this work. When the damage parameter in the models is increased, a less viscous fluid layer appears near the die wall, which decreases the swell ratio to a value lower than the Newtonian swell ratio. Upon further increasing the damage parameter, the high viscosity core layer becomes very small, leading to an increase in the swell ratio compared to smaller damage parameters, approaching the Newtonian value. The existence of a low-viscosity outer layer and a high-viscosity core in the die have a pronounced effect on the swell ratio for thixotropic fluids.

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Section: Thixotropy Modelmentioning

confidence: 99%

Numerical Study of the Effect of Thixotropy on Extrudate Swell

et al. 2021

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“…A fluctuation in the output of an extrusion process is undesired, since this results in inconsistent dimensions of the extrudate. Fluctuating output is especially unfavorable when one attempts to design a die shape at certain processing conditions to optimize the extrudate dimensions for rheologically complex materials [8][9][10]. It is observed that the shape of this output fluctuation is strongly dependent on the chosen minimum gap between the gears.…”

Section: Introductionmentioning

confidence: 99%