Crystallization-induced shrinkage, crystalline, and thermomechanical properties of in Situ polymerized cyclic butylene terephthalate

M. Harsch, J. Karger-Kocsis, A. A. Apostolov

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The polymerization and crystallization of cyclic butylene terephthalate oligomers (CBT) were followed by fiber Bragg grating (FBG) and normal force measurements under isothermal conditions at T = 170 and 190°C, respectively. It was found that the FBG and normal force sense only the crystallization- induced shrinkage. The course of the FBG signal and the normal force as a function of time suggested that crystallization of the polymerized CBT (pCBT) occurs in two steps. The primary crystallization-induced shrinkage is several hundreds by contrast to the secondary one showing several tens in ppm/min unit according to the FBG results. The two-step crystallization was confirmed by normal force measurements. The crystallinity and crystalline structure of the pCBTs were studied by differential scanning calorimetry and wideangle X-ray scattering. It was found that the crystallinity and the crystalline parameters slightly differ for the pCBTs formed at T = 170 and 190°C, respectively. The pCBT produced at T = 190°C had slightly higher crystallinity and more perfect crystals than the pCBT formed at T = 170°C. The reliability of the FBG sensing was checked by thermomechanical analysis (TMA). A fair agreement was established between the thermal contraction and thermal expansion measured by FBG and TMA, respectively.

Original languageEnglish
Pages (from-to)1455-1461
Number of pages7
JournalJournal of Applied Polymer Science
Issue number3
Publication statusPublished - Mar 5 2008



  • CBT oligomer
  • Crystallization
  • Polyesters
  • Ring-opening polymerization
  • Thermal properties

ASJC Scopus subject areas

  • Chemistry(all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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