Free volume dilatation in polymers by ortho-positronium.
Författare
Summary, in English
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.
Avdelning/ar
Publiceringsår
2012
Språk
Engelska
Publikation/Tidskrift/Serie
Journal of Chemical Physics
Volym
136
Issue
24
Dokumenttyp
Artikel i tidskrift
Förlag
American Institute of Physics (AIP)
Ämne
- Chemical Sciences
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 0021-9606