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Visualization of Flow Instabilities for High Density Polyethylene

  • H. Kometani , H. Kitajima , T. Matsumura , T. Suga and T. Kanai
Published/Copyright: March 1, 2013
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International Polymer Processing
From the journal International Polymer Processing Volume 21 Issue 1

Abstract

Two typical flow instabilities of “Shark Skin” and “Melt Fracture” for high density polyethylene were investigated in this report. Experimental measurements were carried out methodically in a wide flow region from the reservoir (entry region) to the die land with a specific slit die. Especially the flow pattern was visualized with a high speed camera and the frequency of the flow instability was analyzed. Corresponding to the visualization analysis, the pressure fluctuation in the slit die and the surface roughness at the die exit were measured simultaneously and these frequency characteristics were analyzed with a FFT (Fast Fourier Transform) analyzer. As for “Shark Skin” region, the irregularity of the surface roughness in the broad frequency band was recognized at the die exit. In spite of this surface roughness, the pressure fluctuation and the fluctuation of the flow pattern at the wall vicinity in the die land were not observed. These results indicate that “Shark Skin” occurs at the die exit. As for “Melt Fracture” region, the periodical oscillation of the flow pattern and the periodical pressure fluctuation which corresponded to the periodical distortion of the extrudate was recognized in the die land. However the periodical oscillation of the flow pattern and the periodical pressure fluctuation could not be recognized in the reservoir (entry region of the die land). These results indicate that “Melt Fracture” is initiated at the die entry and occurs in the die land. Consequently it is clarified that “Shark Skin” occurs at the die exit and the flow instability which lead to “Melt Fracture” is initiated at the die entry and occurs in the die land.

∗ Mail address: H. Kometani, Paper & Film Machinery Laboratory, Hiroshima Research & Development Center, Mitsubishi Heavy Industries, Ltd., 1, Aza Takamichi, Iwatsuka-cho, Nakamura-ku, Nagoya, 453-8515, Japan E-mail:

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Received: 2005-04-17
Accepted: 2006-01-26
Published Online: 2013-03-01
Published in Print: 2006-03-01

© 2006, Hanser Publishers, Munich

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Dedication of the Special Issue of International Polymer Processing in Honor of Prof. James Lindsay White, Editor Emeritus and Founding Editor
  5. Invited Papers
  6. Melt Compounding of Polymeric Nanocomposites
  7. Experiments and Analysis of Effect of Calender Gaps on Melting of PVC Powders in an Intermeshing Counter-rotating Twin-screw Extruder
  8. Quantitative Analysis for Polymer Degradation in the Extrusion Process
  9. Visualization of Flow Instabilities for High Density Polyethylene
  10. Heat Transfer through Metal Walls of Finite Thickness
  11. Simulation and Experimental Verification of Crystallization and Birefringence in Melt Spinning of PET
  12. Structural Development and Properties of Melt Spun Poly(butylene succinate) and Poly(butylene terephthalate-co-succinate-co-adipate) Biodegradable Fibers
  13. External Calibration in PA12 Tube Extrusion
  14. Tubular Film Extrusion Stability of Metallocene Linear Low Density Polyethylene
  15. Multilayer Barrier Film of Biaxially Oriented PA6/EVOH by Double Bubble Tubular Film Process
  16. PPS News
  17. PPS News
  18. Seikei-Kakou Abstracts
  19. Seikei-Kakou Abstracts
https://doi.org/10.3139/217.0057

Articles in the same Issue

  1. Contents
  2. Contents
  3. Editorial
  4. Dedication of the Special Issue of International Polymer Processing in Honor of Prof. James Lindsay White, Editor Emeritus and Founding Editor
  5. Invited Papers
  6. Melt Compounding of Polymeric Nanocomposites
  7. Experiments and Analysis of Effect of Calender Gaps on Melting of PVC Powders in an Intermeshing Counter-rotating Twin-screw Extruder
  8. Quantitative Analysis for Polymer Degradation in the Extrusion Process
  9. Visualization of Flow Instabilities for High Density Polyethylene
  10. Heat Transfer through Metal Walls of Finite Thickness
  11. Simulation and Experimental Verification of Crystallization and Birefringence in Melt Spinning of PET
  12. Structural Development and Properties of Melt Spun Poly(butylene succinate) and Poly(butylene terephthalate-co-succinate-co-adipate) Biodegradable Fibers
  13. External Calibration in PA12 Tube Extrusion
  14. Tubular Film Extrusion Stability of Metallocene Linear Low Density Polyethylene
  15. Multilayer Barrier Film of Biaxially Oriented PA6/EVOH by Double Bubble Tubular Film Process
  16. PPS News
  17. PPS News
  18. Seikei-Kakou Abstracts
  19. Seikei-Kakou Abstracts
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