Work of fracture and strain-induced cold crystallization behavior of amorphous copolyester sheets

J. Karger-Kocsis, E. J. Moskala, P. P. Shang

Research output: Contribution to journalArticle

23 Citations (Scopus)


The toughness of amorphous copolyester sheets was assessed by the essential work of fracture (EWF) concept. While the yielding-related work of fracture terms did not change significantly, the necking-related parameters strongly decreased with decreasing entanglement density of the copolyesters having different amounts of cyclohexylenedimethylene (CHDM) units in their backbones. Furthermore, copolyesters with high CHDM content and thus less entanglement density showed full recovery of the necked region beyond the glass transition temperature, i.e. the 'plastic' zone in the related specimens formed by cold drawing and not by true plastic deformation. By contrast, the copolyester with negligible amount of CHDM did not show this shape recovery. Modulated differential scanning calorimetry (MDSC) revealed that the necking in the latter system was accompanied by strain-induced crystallization. The superior work hardening in the necking stage of the respective poly(ethylene terephthalate) (PET) specimens can thus be ascribed to stretching of the entanglement network with superimposed crystallization.

Original languageEnglish
Pages (from-to)671-678
Number of pages8
JournalJournal of Thermal Analysis and Calorimetry
Issue number3
Publication statusPublished - May 9 2001


  • Amorphous copolyesters
  • Cold crystallization
  • Cold drawing
  • Entanglement
  • Essential work of fracture
  • Modulated DSC
  • Necking

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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