Free volume dilatation in polymers by ortho-positronium.

Research output: Contribution to journalArticle


The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which at the higher temperatures approach the o-Ps lifetimes. Nanoscale viscosities were estimated using Navier-Stokes equation and were found to be several orders of magnitude lower than the macroscopic viscosity at the same temperature.


  • Petra Winberg
  • Morten Eldrup
  • Frans Maurer
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Chemical Sciences
Original languageEnglish
Article number244902
JournalJournal of Chemical Physics
Issue number24
Publication statusPublished - 2012
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)