Free volume and crystallinity of poly(ethylene naphthalate) treated in pressurized carbon dioxide

Research output: Contribution to journalArticle


The free volume and crystallization behaviour of poly(ethylene naphthalate) (PEN) treated in pressurized carbon dioxide was studied, using Positron Annihilation Lifetime Spectroscopy (PALS) and Differential Scanning Calorimetry (DSC). PALS probes the values of free volume cavity sizes in materials, thus making it possible to investigate the effect of pressurized carbon dioxide treatment on free volume hole sizes in PEN. The crystallinity and melting behaviour of PEN was analyzed with temperature modulated DSC. We found that the carbon dioxide pressure during treatment of PEN was the prime parameter affecting the value of free volume after the treatment. The free volume sizes were observed to be insensitive to the other two parameters, temperature and time. Increasing the time of the treatment however, increased the crystallinity of PEN. Interestingly, this was not coupled to a decrease in ortho-Positronium intensity as was expected, indicating that positronium may form in the crystalline fraction of the polymer as well as in the amorphous fraction. (C) 2009 Elsevier Ltd. All rights reserved.


  • Anna Andersson
  • Wentao Zhai
  • Jian Yu
  • Jiasong He
  • Frans Maurer
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Chemical Sciences


  • Positron annihilation, Supercritical fluids, Temperature modulated DSC
Original languageEnglish
Pages (from-to)146-152
Issue number1
Publication statusPublished - 2010
Publication categoryResearch

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Polymer and Materials Chemistry (LTH) (011001041)