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Flow Implications in the Processing of Tetrafluoroethylene/Hexafluoropropylene Copolymers

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Published/Copyright: May 28, 2013
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International Polymer Processing
From the journal International Polymer Processing Volume 10 Issue 3

Abstract

The melt fracture behavior of two Teflon® resins was studied in capillary extrusion in order to identify the critical conditions for the onset of melt fracture and wall slip. These resins were copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) and TFE/HFP/PAVE (perfluoro (alkyl vinyl ether)) (PAVE) respectively. The incorporation of the third monomer in the molecules of the resin was found to improve the processability of polymer without substantially changing its rheology. Surface melt fracture (sharkskin) appeared at wall shear stresses greater than about 0.18 MPa, practically independent of temperature in the range of 300 to 350°C. At higher apparent shear rates oscillating melt fracture was observed due to the presence of wall slip and compressibility of the melt. Furthermore, a superextrusion region was identified at apparent rates greater than about 700 s−1, beyond those where oscillating melt fracture was obtained. In this region, the extrudate appears again smooth. Finally, it was found that the addition of 0.1 % of polyethylene in the resins, reduces dramatically the pressure drop along the capillary die and eliminates extrudate distortion over the whole range of apparent shear rates up to the superextrusion region.

* Mail address: Prof. Savvas G. Hatzikiriakos, Department of Chemical Engineering, University of British Columbia, 2216 Main Mall, Vancouver, BC V6T 1Z4 Canada
Received: 1995-1-10
Accepted: 1995-5-1
Published Online: 2013-05-28
Published in Print: 1995-09-01

© 1995, Carl Hanser Verlag, Munich

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Fifteenth in a Series: Ikegai Corporation: From Engine Lathes to Twin Screw Extruders
  5. Die Extrusion
  6. Analysis of Polymer Flow through Coathanger Melt Distributors
  7. Viscosity and the Formation of Die Drool at the Polymer-Metal Interfaces
  8. Flow Implications in the Processing of Tetrafluoroethylene/Hexafluoropropylene Copolymers
  9. Reactive Processing
  10. Thermal/Peroxide Induced Degradation and Maleation of Polypropylene by Reactive Extrusion
  11. Fibers and Films
  12. Biaxially Oriented Polyethylene Films by Compression of Injection Moldings
  13. Tubular Film Blowing
  14. Tubular Film Blowing
  15. Molding
  16. Elastic Calculation of Residual Stresses in Injection Molding
  17. On the Limitations of Shear Induced Crystallization in Polypropylene Melts
  18. Structure and Properties of Injection Moldings of β-Crystal Nucleator-Added Polypropylene
  19. Study on the Performance of Cooling Systems in Precision Injection Molds
  20. Measurement of Planar Orientation of Fibers for Reinforced Thermoplastics Using Image Processing
  21. Welding
  22. Dynamics and Structure Development in Spin Welding of Polyvinylidene Fluoride Cylindrical Rods
https://doi.org/10.3139/217.950204

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Fifteenth in a Series: Ikegai Corporation: From Engine Lathes to Twin Screw Extruders
  5. Die Extrusion
  6. Analysis of Polymer Flow through Coathanger Melt Distributors
  7. Viscosity and the Formation of Die Drool at the Polymer-Metal Interfaces
  8. Flow Implications in the Processing of Tetrafluoroethylene/Hexafluoropropylene Copolymers
  9. Reactive Processing
  10. Thermal/Peroxide Induced Degradation and Maleation of Polypropylene by Reactive Extrusion
  11. Fibers and Films
  12. Biaxially Oriented Polyethylene Films by Compression of Injection Moldings
  13. Tubular Film Blowing
  14. Tubular Film Blowing
  15. Molding
  16. Elastic Calculation of Residual Stresses in Injection Molding
  17. On the Limitations of Shear Induced Crystallization in Polypropylene Melts
  18. Structure and Properties of Injection Moldings of β-Crystal Nucleator-Added Polypropylene
  19. Study on the Performance of Cooling Systems in Precision Injection Molds
  20. Measurement of Planar Orientation of Fibers for Reinforced Thermoplastics Using Image Processing
  21. Welding
  22. Dynamics and Structure Development in Spin Welding of Polyvinylidene Fluoride Cylindrical Rods
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