Journal of Materials Science

, Volume 43, Issue 21, pp 6866–6871 | Cite as

Changes in tensile properties for the PET films by the treatment in supercritical carbon dioxide fluid

  • Yutaka KawaharaEmail author
  • Tomohiro Kurooka
  • Dohiko Terada


Poly (ethylene terephthalate) films were treated in supercritical CO2 (s-CO2) fluid, and the modifications in tensile properties were investigated. The yield load peaks became ambiguous and the breaking strains and loads decreased for the treated films. However, the tensile modulus and the yield strain were almost unchanged after the treatments. The yield strain is related to the interplay between the amorphous entanglement density and the stability of crystal blocks. WAXD patterns for the films were hardly modified through the treatment. Thus the orientation for the crystal blocks seems to be unchanged. Moreover, laser Raman microprobe spectroscopic analyses revealed that the orientation of molecular chains is almost retained after the treatments. Thus it is natural to assume that the interplay between the amorphous entanglement density and the stability of crystal blocks will also be kept constant even though the swelling of amorphous regions with s-CO2 occurs during the treatments. From differential scanning calorimetry measurements, it was found that the heat of fusion for the crystallites was a little increased without shifting the peak position after the treatment. Therefore, the increase in crystallinity is not due to the thickening or crystal perfecting for primary lamellae, but due to the secondary crystallization. The increase in crystallinity caused by the secondary lamellae crystallized and combined onto the primary lamellae seems to have reduced the amorphous chains to be deformed easily at tensile tests. Then the breaking strains and loads decreased for the treated films.


Differential Scanning Calorimetry Measurement Ethylene Terephthalate Machine Direction Secondary Crystallization Secondary Lamella 


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Yutaka Kawahara
    • 1
    Email author
  • Tomohiro Kurooka
    • 2
  • Dohiko Terada
    • 2
  1. 1.Department of Chemistry and Chemical BiologyGunma UniversityKiryuJapan
  2. 2.Division of Advanced Fibro-Science, Graduate SchoolKyoto Institute of TechnologyKyotoJapan

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