Effect of a radial flow foregoing a capillary die on the behavior of extruded PDMS: velocity field–distorted strand correlation

The present work aimed to investigate the influence of flow geometry on volume instability associated to a linear polydimethylsiloxane (PDMS). To do so, a convergent radial flow was created at the die entrance. The performed particle image velocimetry (PIV) recordings under unstable flow regime, in...

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Bibliographic Details
Published in:Rheologica acta 2020-07, Vol.59 (7), p.425-434
Main Authors: Ketata, Manel, Ayadi, Abdehak, Bradai, Chedly, Abid, Mohamed Salah
Format: Article
Language:English
Subjects:
Capillary flow
Characterization and Evaluation of Materials
Chemistry and Materials Science
Complex Fluids and Microfluidics
Entrances
Extrusion dies
Flow geometry
Flow stability
Food Science
Materials Science
Mechanical Engineering
Melt fracture
Original Contribution
Particle image velocimetry
Polydimethylsiloxane
Polymer Sciences
Radial flow
Silicone resins
Soft and Granular Matter
Velocity distribution
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Summary:The present work aimed to investigate the influence of flow geometry on volume instability associated to a linear polydimethylsiloxane (PDMS). To do so, a convergent radial flow was created at the die entrance. The performed particle image velocimetry (PIV) recordings under unstable flow regime, in capillary rheometer, characterized by the new entrance zone, show a new pattern of streamlines above the die and a disappearance of the vortex developed in the corner of the reservoir. Photographs of the extrudate strands obtained at the die exit depict a new morphology of defect which appears with a well-established radial flow. These results led to the correlation agreement between the gross melt fracture and the flow instability at the entrance zone. It also proved the importance of elongational and shear components linked to the upstream flow in the appearance and development of volume distortion.
ISSN:0035-4511
1435-1528
DOI:10.1007/s00397-020-01207-7