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The upstream region radial flow and average molecular weight effect on the molten PDMS processibility

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Abstract

The present study investigated the influence of a created radial flow upstream of the extrusion die and the average molecular weight on the processibility of polymer melts. Two linear polydimethylsiloxanes (PDMS) of different molecular weights were considered. A convergent radial flow was created at the entrance zone by imposing a rod upstream the capillary die. The flow of the tested PDMSs has been studied using capillary rheometry and particle image velocimetry (PIV). The obtained experimental results revealed a transition zone, on the flow curves (associated to the two PDMSs), located between the end of the surface instability zone and the onset of the gross melt fracture. The morphology of the associated extrudate strand is changed. Furthermore, the PIV recording under the unstable flow shows a new flow pattern in the front of the die due to the created radial flow. The possible origin of the new flow instability was discussed.

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Authors and Affiliations

  1. LASEM, National Engineering School of Sfax, University of Sfax, Sfax, Tunisia

    Manel Ketata & Chedly Bradai

  2. Advanced Fluid Dynamics, Energetics and Environment (AFD2E), National Engineering School of Sfax, University of Sfax, Sfax, Tunisia

    Adelhak Ayadi

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  1. Manel Ketata
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  2. Adelhak Ayadi
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  3. Chedly Bradai
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Correspondence to Manel Ketata.

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Ketata, M., Ayadi, A. & Bradai, C. The upstream region radial flow and average molecular weight effect on the molten PDMS processibility. Rheol Acta 60, 775–785 (2021). https://doi.org/10.1007/s00397-021-01311-2

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  • DOI: https://doi.org/10.1007/s00397-021-01311-2

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